Ajax

Solar Output Lower Than Expected

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I've been chasing this tail for a few weeks in a few different places. I think it's time to consolidate the discussion here.

Facts:

Symptoms:

  • Controller power output consistently reads lower than expected for prevailing solar conditions. (Perfect alignment, perfectly cloudless days)
  • Voltage output from panel to controller (indicated): 14 to high 15's
  • Amperage output from panel to controller (indicated):  1.5 to 3 amps
  • Total power from panel to controller (indicated) usually in the 20 - 30 watt range, highest ever recorded was 56 watts for a 125 watt panel
  • Values recorded with battery at various depths of discharge, various electrical loads applied. This doesn't seem to affect the output of the controller.
  • Indicated outputs from controller to battery are similar, voltages usually a bit lower than what the panel is shoving into the controller.

Tests conducted so far:

  • Triple checked all wiring connections for tightness and correctness in accordance with the manuals of the panel and the controller
  • Disconnected panel from wiring run and controller.  Multi-meter indicates 127.75 watts output (17.5 volts out, 7.5 amps out=127.75) Panel seems healthy.
  • Connected panel to wiring run and controller. Meter indicates 93 watts at the end of the run, measured at the controller terminals.
    • Note: I do have an excess length of wire because I wanted the ability to move the panel higher, later if I desired. Possible voltage drop due to lengthy cable run?
  • In spite of the fact that I measure 93 watts at the end of the cables, the controller still indicates only in the 20's to low 50's wattage input from the solar panel. Why?

I've had this panel and controller for a couple of years. It's always output this low. Yes, I'm an idiot and never questioned why until recently. Let's skip past that and get to the possible causes.

The only causes that spring to mind are faulty controller or wiring run is too long, causing an excessive voltage drop. I figure the total run is 30-40 feet of cable with MC-4 connectors on the panel itself.

Lastly, there's one little statement in the Victron manual that gives me pause: 

12V battery and mono- or polycristalline panels connected to a 75V controller ● Minimum number of cells in series: 36 (12V panel).● Recommended number of cells for highest controller efficiency: 72(2x 12V panel in series or 1x 24V panel).● Maximum: 108 cells (3x 12V panel in series)

Notice that the manual states that the "minimum" number of cells is 36.  My Solbian panel only has 32 cells.  Could this be the problem?

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sounds like you've done everything right. If you can live with the voltage drop from the long run, you should definitely look at the MPPT controller itself. It might be worth $200 to get someone else's controller to see if it works. Hamilton Ferris has a range of MPPT controllers that would fit the bill. 

I actually have one that's not in use right now that I could lend you if you pm your contact info. It's rudimentary but I think it can handle your wattage.

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Losing 25% of your power in the wiring is excessive, which points to under-rated wiring. It also sounds like Victron wants a minimum input voltage (expressed in terms of the number of series cells). Since you're already about 10% below that, you're pushing it even without the under-rated wiring. This isn't necessarily fatal, since Victron probably assumes some losses in the run.

No matter what, your panel wiring needs an upgrade. I'd try shortening the run of wire from the panel to the controller as much as possible and also going up in size to #10 or even #8 wiring to minimize voltage drop and see if the Victron behaves better. If it does, you're golden. Failing that, you might consider getting a second panel to put in series with the first or replacing the Victron with unit that'll handle the lower input voltage.

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I looked at the manual (here).  As you have noticed your panel is a few cells short of the minimum. That makes the ideal MPP a few volts lower. Your panel has a nominal MPP of 16v. An observed 15+v at the controller suggests that the boost / buck thing on the controller is working.  The controller should work at Vbatt +1 but efficiency could go way down. The long wire run is not going to help at all. None of which adds anything to what you already knew. I'd check the temp sensor and charge program just to make sure the controller isn't intentionally limiting the power -- maybe you can reset it to factory defaults? Next, I'd shorten up the wires. You can always splice the excess back on again.

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You guys are awesome.  I'll shorten the run and report back on the size of the wire... but I'll let you know that it barely fits into the controller terminals so I don't think it's undersized. 

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The manual says it can take up to 10 AWG wire. Do yourself a favor and buy one of these for the ends of the wires:

https://www.amazon.com/gp/product/B073TZ5BBG/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1

It'll make it so much easier and more reliable to use screw terminals like those on the Victron.

 

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How did you actually measure 127 W and 93 W? Open voltage and short circuit current? Or did you use some load?

As stated your panel has too low mpp voltage for this controller, which is only buck and doesn't boost. The cables and higher than the very low standard panel temperature will further drop the mpp voltage.

What your battery voltage has been when you get 20-56 W?

This panel, especially with long cables, would deliver more with a cheap PWM controller.

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2 hours ago, Joakim said:

How did you actually measure 127 W and 93 W? 

Good catch. If the 127W is Voc * Isc then the panel is not going to produce 127W.

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This controller needs Vbat + 5 V to start and then Vbat + 1 V to continue. It really should not be used with a 32 cell panel and even a standard 36 cell "12 V" panel will not start when it should. It's just a bad controller for a 12 V panel.

There are better mppt controllers for 12 V panels, but a 32 cell panel should be used with PWM. Mpp voltage is just too close to battery voltage. Mppt controller will likely work in PWM mode, for which it is less efficient than a good PWM controller.

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7 hours ago, Joakim said:

How did you actually measure 127 W and 93 W? Open voltage and short circuit current? Or did you use some load?

As stated your panel has too low mpp voltage for this controller, which is only buck and doesn't boost. The cables and higher than the very low standard panel temperature will further drop the mpp voltage.

What your battery voltage has been when you get 20-56 W?

This panel, especially with long cables, would deliver more with a cheap PWM controller.

Update-  I found the cable specs for the cabling that I purchased-  50 feet of 10ga. wiring. I can probably reduce that to 15-20 feet. The voltage loss crunches out to:

Voltage drop: 0.75
Voltage drop percentage: 4.28%
Voltage at the end: 16.75

Yes, open V and short current by simple measuring across the disconnected panel leads with my meter. 

I understand what you're saying but I've never had a problem with the panel generating enough of a voltage differential to "start" the controller's charging cycle. 

The first thing I'm going to do, is shorten the wiring run as much as possible and reevaluate the output. If the output is still insufficient, I will have to make a decision-  buy a higher output panel that works better with my controller, or buy a controller that works better with my existing panel.

I know it seems silly to spend hundreds of dollars on a new panel, but I could still use the extra power.  PWM is just so inefficient. I'm hopeful that I can find an MPPT controller that will be more compatible with the CP125 panel.  If I decide to upgrade to a more powerful panel, I should be able to sell my existing panel since it works perfectly.

 

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39 minutes ago, Ajax said:

Update-  I found the cable specs for the cabling that I purchased-  50 feet of 10ga. wiring. I can probably reduce that to 15-20 feet. The voltage loss crunches out to:

Voltage drop: 0.75
Voltage drop percentage: 4.28%
Voltage at the end: 16.75

Yes, open V and short current by simple measuring across the disconnected panel leads with my meter. 

I understand what you're saying but I've never had a problem with the panel generating enough of a voltage differential to "start" the controller's charging cycle. 

The first thing I'm going to do, is shorten the wiring run as much as possible and reevaluate the output. If the output is still insufficient, I will have to make a decision-  buy a higher output panel that works better with my controller, or buy a controller that works better with my existing panel.

I know it seems silly to spend hundreds of dollars on a new panel, but I could still use the extra power.  PWM is just so inefficient. I'm hopeful that I can find an MPPT controller that will be more compatible with the CP125 panel.  If I decide to upgrade to a more powerful panel, I should be able to sell my existing panel since it works perfectly.

 

With only 17.5 V open voltage no MPPT charger is going to work properly and they all will be LESS efficient than PWM. Probably there is something wrong with your panel, since specs say 20 V open voltage. You get NO CURRENT at all at open voltage. For a decent current you need to 4-5 V below open voltage. Thus at 17.5 V you get good current at ~13 V. And then you have voltage drop at the cables and voltage drop for the controller. Buck MPPT controller always has rather high voltage drop, clearly higher than a PWM.

Measure how much current you get, if you connect the panel directly to the battery. Also measure the voltage when the panel is connected.

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31 minutes ago, Joakim said:

With only 17.5 V open voltage no MPPT charger is going to work properly and they all will be LESS efficient than PWM. Probably there is something wrong with your panel, since specs say 20 V open voltage. You get NO CURRENT at all at open voltage. For a decent current you need to 4-5 V below open voltage. Thus at 17.5 V you get good current at ~13 V. And then you have voltage drop at the cables and voltage drop for the controller. Buck MPPT controller always has rather high voltage drop, clearly higher than a PWM.

Measure how much current you get, if you connect the panel directly to the battery. Also measure the voltage when the panel is connected.

I hope you mean that I should only connect the panel directly to the battery momentarily for this test. The panel is going to be hammering my battery without any regulation.  The battery is also fully charged now, so it's not going to accept much energy from the panel.

The Genasun GV-10 looks like a viable alternative controller. 

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I've also been in touch with the vendor who sold me that panel.

He just sent me an email that states that they've had good results using the CP125 panel with the Victron controller. He states that although the number of cells is lower than Victron would like, they are larger cells and generate the necessary voltage to be fully compatible with the Victron controller.

His advice to me is to cut way back on the excess wire and reevaluate.  It's a cost-free test, so I'll do that this afternoon and report back.

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Your vendor may not be very knowledgable. Larger cells will produce more current, not more voltage. The Genasun is a great controller, but so is the Victron. If you have the space for it, your best solution at this point is to buy a second panel and run them in series. No wasted money, the wiring will still work as the current is the same. 

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1 hour ago, DDW said:

Your vendor may not be very knowledgable. Larger cells will produce more current, not more voltage. The Genasun is a great controller, but so is the Victron. If you have the space for it, your best solution at this point is to buy a second panel and run them in series. No wasted money, the wiring will still work as the current is the same. 

I thought about getting another panel but the CP125 is an older model that I think is out of production. I'll see if I can find them, and see what they cost. 

Also, real estate for two large panels might be problematic. I love my current configuration because I can quickly and easily remove and stow the panel for racing or if strong weather is imminent.  I don't use a bimini.  If I put 2 panels in a bimini, it becomes more problematic to remove them and stow the bimini.

My future plans for more solar included 2 narrow panels on the cabin top tied to a second controller.

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Ok, the CP125 is only available from emarine.com and they want hella price for it. No thanks.

@DDW I think you're right about my solar panel vendor not being knowledgeable.  I finally got a tech at Victron and his diagnosis is the same as @Joakim and he also advised me to buy a PWM controller. Sigh...

I just bought a simple, PWM off Amazon for $20. I figure it's a very cheap experiment to try it out.  When/if I upgrade to a better panel in the future, I'll have the Victron available for it.

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4 hours ago, Ajax said:

PWM is just so inefficient.

Since you love your setup and it has been working for you maybe just shorten up the wires and step away from the multimeter?

Rule 1: if it ain't broke, don't fix it.

If you can live by that rule you're a better man than I.

Anyway, your mention of PWM inefficiency reminds me that it's not clear what the typical variance in battery state is in use. I know PWM is a shorthand for controllers that only do current limiting as distinct from MPPT. However, PWM is a current limiting scheme that many controllers including most MPPT controllers use. When it is being used to limit current the panel is producing more power than the battery can accept. At that point there's no advantage to MPPT.

***Breaking news!*** I see you ordered a PWM controller. Now you can do A/B testing. That should keep you out of trouble :) Good luck.

 

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@weightless  Well, I love the physical setup. I don't love that the panel only outputs 1/2 the current that my fridge draws when it could output nearly double what the fridge draws.

By the end of 4 days, I needed to run the engine to put something back into the battery.

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2 hours ago, weightless said:

I know PWM is a shorthand for controllers that only do current limiting as distinct from MPPT. However, PWM is a current limiting scheme that many controllers including most MPPT controllers use. When it is being used to limit current the panel is producing more power than the battery can accept. At that point there's no advantage to MPPT

Having designed a MPPT controller and a PWM controller (just for my own use) I would say it a bit differently. The main difference between PWM and MPPT is that MPPT uses a switching mode regulator, which can increase the current when the voltage is lowered. PWM just cuts the panel off for part of the time. They both regulate the current in a way that battery voltage does not rise above the value set. MPPT limits always the current. When battery voltage is not too high, it still regulates the output current, since that will determine the input voltage and thus MPP point. So output current is regulated in a way to reach desired input voltage. If the panel voltage is too low, MPPT will work just as PWM, but now the current will flow through a coil and a FET (+ often two current sense resistors) while PWM controller only has a FET.

It is of course true that when PWM starts to limit the current (not on all the time = panel just directly connected to the battery) MPPT is not at all more efficient. Both are limited by the amount of current the battery can take.

With PWM controllers you don't usually have to care much about cabling losses, since there is voltage to be lost anyway.

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6 hours ago, Ajax said:

I hope you mean that I should only connect the panel directly to the battery momentarily for this test. The panel is going to be hammering my battery without any regulation.  The battery is also fully charged now, so it's not going to accept much energy from the panel.

The Genasun GV-10 looks like a viable alternative controller. 

Yes just for the test to see can you get 7-8  A out of the panel as you should (no shadows and directed towards the sun). You can put all power usage on to lower the voltage and enable the whole 7-8 A current to be taken at normal charging voltage. I have just 50 W panel and putting navigational lights on is enough for testing it. Only tricolor is LED. I get 4 A from other navigational lights.

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Yup you need to connect the panel directly to the battery on a sunny day and measure the amps.

Ten minutes at 8 amps will not do your battery harm.

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2 hours ago, Joakim said:

The main difference between PWM and MPPT is that MPPT uses a switching mode regulator, which can increase the current when the voltage is lowered.

Yes. I think that's exactly right. I didn't intend to suggest otherwise.

I was trying to get at a different concern. I wanted to know if Ajax's system was being limited by by the battery acceptance current. If so, then his concern about efficiency would be easy to allay; all cats are grey in the dark. Turns out he can use the extra power, so that's moot.

I was also hinting at a more pedantic issue. I'm going to elaborate on that issue and then end the post. Now might be a good time to scroll down to the next reply...

From my reading it seems that PWM is used generically to mean current limiting in solar battery controller speak. Properly I think PWM has a frequency and duty cycle. So, my solar charge controller which is essentially a Schmidt trigger and a relay is not PWM. Some cheap controllers that say they are PWM do not implement PWM. MPPT are doing something very or even exactly PWMy when they are current limiting.  PWM is reasonably efficient and has some other nice features. So, I think calling all non-MPPT controllers PWM is inaccurate, potentially confusing and a little unfair to PWM. The point seemed relevant because Ajax said "PWM is just so inefficient". I completely understood what he meant but I wanted to stand up for PWM as a thing. If I don't who will? ;) 

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7 hours ago, IStream said:

FWIW, Maine Sail has a good article on PWM versus MPPT. 

TLDR: once the battery is out of bulk phase, MPPT doesn't have an advantage over PWM.

https://marinehowto.com/mppt-vs-pwm-solar-controllers/

I still think you should shorten the wires regardless of your controller. 

Oh yes, I'll be shortening the run no matter what. 

Like I said, I just kept the extra length while I worked out possible installation locations. I'm going to keep 3-4 extra feet that will allow me to raise the panel to an arch or Bimini in the future, if I decide to install one and I'll cut out the excess 30 feet.

The PWM controller arrives today. If I have time, I'll cut out the excess, perform a quick output check with the Victron controller and if necessary, swap in the PWM controller. I do suspect that I'll end up installing the PWM controller. There's probably no way around it.  I'll box the Victron controller and store it in the house until I feel like dropping $700 more dollars on a more powerful Solbian panel or possibly a pair of them that will be mounted on the cabin top.

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Shame you already put out  $$ on a cheapy PWM. For a few more - OK, five times as much - you could have got one of these:

https://2n1s7w3qw84d2ysnx3ia2bct-wpengine.netdna-ssl.com/wp-content/uploads/2014/02/SSDuoENG2_111.pdf

Replaced the old Steca that came with my boat with this Morningstar SSD25 and have been totally happy. I have two old-ish, odd panels, one 90W, one 35W, and routinely see 7.5A bulk phase current. The real advantage of this particular model is that it can charge two independent batteries. The meter is more $, but it's all quality stuff.

I worked on St. Lucia for a few days late last year and happened to meet a professional PV engineer staying in the same hotel. He confirmed that for small systems like ours there is little or no advantage to MPPT.

I admit that living at 10 degrees North does have certain advantages in this respect.

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18 minutes ago, seabell said:

Shame you already put out  $$ on a cheapy PWM. For a few more - OK, five times as much - you could have got one of these:

https://2n1s7w3qw84d2ysnx3ia2bct-wpengine.netdna-ssl.com/wp-content/uploads/2014/02/SSDuoENG2_111.pdf

Replaced the old Steca that came with my boat with this Morningstar SSD25 and have been totally happy. I have two old-ish, odd panels, one 90W, one 35W, and routinely see 7.5A bulk phase current. The real advantage of this particular model is that it can charge two independent batteries. The meter is more $, but it's all quality stuff.

I worked on St. Lucia for a few days late last year and happened to meet a professional PV engineer staying in the same hotel. He confirmed that for small systems like ours there is little or no advantage to MPPT.

I admit that living at 10 degrees North does have certain advantages in this respect.

Yeah, I guess I've fallen for the market hype of MPPT.  Even if I add another pair of smaller panels to my cabin top I'm still looking at an insufficient number of cells for a Victron controller. 

The purpose of my cheap-o PWM controller is mainly to perform a charging experiment. If the panel checks out OK, I might splurge for the controller that you linked.  One of my concerns is having a safe, reliable controller that won't fail in a destructive mode and burn up wiring or boil the batteries to death.

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If you only run a single bank there's no need for the 'Duo' model (which appears to be unique at this capacity/price point).

For the sake of comparison, my system keeps a pair of T-105 house batteries and a Costco-style 'maintenance free' FLA unit happily topped off and ready for weekend jaunts. The one minor aspect I could do without is the monthly equalization phase. Haven't checked to see if I can disable it or adjust the interval if I buy the PC interface cable though, but can't say it has done any harm. Just feel it is not necessary to equalize quite so often, and it probably increases water consumption.

Edit: Appears that the equalization can indeed be configured, so looks like a USB-MODBUS interface is in my future. http://support.morningstarcorp.com/wp-content/uploads/2014/07/SSD.APP_.Modbus.EN_.03.pdf

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FYI I have  405 watts of solar[ 3 x Kyocera 135 w panels ]  I use a Blue Sky 2000E MPPT controller. I am a full time liveaboard. The set up has been running for more than 10 years. I needed a new controller after 8 years. The dead one still operated in equalisation mode. 

I would use the same set up again. 

Be cautious if buying a cheap controller that claims to be MPPT some are just PWN.

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Morningstar makes decent hardware. 

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1 hour ago, IStream said:

Morningstar makes decent hardware. 

Wow, they have an excellent "calculator" page to help select the proper controller. It even has my exact panel in its library.

http://string-calculator.morningstarcorp.com/#manufacturer=1867&module=73740&product=15&vmin=11.9&vmax=14&tmin=-11.666666666666668&tmax=35&tminunits=f&tmaxunits=f

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I had similar experience, and then realized my batteries were basically full so no place for power to go, panel would only show about 5-10 watts on a 200 amp system.  I turned on the fridge, instruments,  radio, and all of a sudden its showing 156 watts in on the controller.

 

 

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4 hours ago, TQA said:

Kyocera 135 w panels

I owe a big debt of gratitude to Kyocera. They treated me remarkably well when I had an issue with a panel.

I was in a somewhat off the main track town when I noticed that a join had failed inside one of my panels which had been purchased in a different country some years previously. So, I emailed Kyocera corporate in yet another country to see if I could get some pointers on fixing the problem. It looked to me like I might be able to slit open the backing and solder the joint but I figured a bit of tech support might help. Their response was "don't touch anything, we'll send you new panels." I responded "that will be difficult and expensive." They said, "don't worry about it. We'll take care of everything just put the old panels in the boxes that the replacements come in."  And they did. They organized courier service both ways and took care of all the details. 

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A couple eyebrow raisers I note which may not be your problem.  You're using a 32 cell panel which

"Might Google 'self regulating solar panels' which usually used 30, maybe 32 or 33 cells.  The idea was if they could not make amps at enough voltage, then they did not need a charge controller.  Problem was they could barely charge a battery, making them about useless."

Not quite true. Sunpower makes a pricey 32 cell panel using IBC n-type base cells which have a higher per cell voltage,  and backside contacts (no metal ribbons cross the face of the cell).  But your Italian panel does not use IBC cells, as their spec sheet clearly shows front face contacts on the cells.  Solbian now makes panels using Sunpower's IBC cells (SP Series panels), also quite expensive.  

Second eyebrow raiser, their spec sheet states that a charge controller is included with your  panel(?).  Was your Victron controller included with the panel?  It's a very good controller, but might not pair well with a 32 cell panel.

Last, sad to say the chinese have been marketing fake Solbian panels using substandard cells which have nowhere near the output of a genuine panel.  I'm suspicious of your vendor in that he told you the larger cells produce a higher voltage,  obviously not true.

I'm parroting advice from above messages and you're looking into the right things to find the problem. 

50' of 10g wire is pushing it hard @  12.3v/7a  maximum panel output, a 0.7v drop, which is the difference between healthy and no charging.  Not salient to this discussion but I've got a vehicle house battery setup in the back of my car to run a refrigerator 24/7, connected to the vehicle battery, 15' of wire, controlled by the charging system of the car.  I originally used 14g wire and the house battery charged very slowly if at all.  Switched to 8g wire and now it charges the house battery like a champ, 25+ amps into the battery when it's nearly discharged.  Too much voltage drop in the thinner wire was the problem.  You can check this by directly connecting the panel to the controller with short wires into a nearly dead battery bank. Seeing healthy charging amperage now?

Or, your panel may be junk. Sure 20+v open circuit at the panel seems good, but even a shitty panel can do that in bright sun.  It's when the panel is loaded up feeding into a near dead battery that the actual panel output can be determined.  Can you borrow a good 125w panel from somebody, hook it up to your 50' of wire/controller/battery system in bright sun with the battery discharged below 50%?  If you're not seeing a 7amps or so charging rate,  your system is the problem, not the panel.

As an aside, I've run into many folks who spec'd out their solar system (car/cabin/boat/backpackers) who for example assume a 125w panel will crank 10 amps into their 12v battery when it's sunny, from dead to fully charged.  Nay, that's not how it works, and they will be disappointed.  At best, my various moderate power (100w-30w) panels only deliver about 70% rated amperage max on a good day at noon, then taper off to 10-5% when the battery is nearly full.  Better is to double your panel output  purchase after calculating your energy use budget to account for cloudy days, poor panel orientation, shadowing, etc.   A silver lining  is that some of my panels are over 20 years old and still producing factory output, a long term investment which can be amortized.

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Hmmm. Lots of words. Little useful information, and you contradict yourself:

"At best, my various moderate power (100w-30w) panels only deliver about 70% rated amperage max on a good day"

followed by:

"some of my panels are over 20 years old and still producing factory output"

Are you sure you know what you are talking about?

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15 hours ago, seabell said:

Hmmm. Lots of words. Little useful information, and you contradict yourself:

"At best, my various moderate power (100w-30w) panels only deliver about 70% rated amperage max on a good day"

followed by:

"some of my panels are over 20 years old and still producing factory output"

Are you sure you know what you are talking about?

Um, yes.  Although I misspoke, "panels only deliver about 70% rated amperage max on a good day" should read  ".  .  .  70% rated wattage max  .  .  .".

My panels are small 12v (100w or less) so I use a basic 1 stage controller.   It would have been cheaper to buy a  130w panel than to buy a 100w panel and a MPPT controller.  Panels are rated at their Vmpp voltage,  15.6 volts  in the case of my 20 watt panel spec sheet.  But  my discharged battery  during bulk phase charging is at or below 13.7v+-, and using NOCT standard conditions  the panel delivers 14watts.  So when brand new this panel delivers 70% of its rated wattage into the battery in real world conditions.  Therefore my panel is still producing factory output 20 years later, when measured using a VOM, minus a few percent maybe.

Do you think a 100w panel actually delivers 100w under NOCT conditions?  Even with a MPPT controller it will not.  Since you think I'm a dunce, here's the actual spec sheet numbers for the Shell ST20 20w solar panel discussed above:

Clipboard01.gif.5de81d5987f89e0562f397d233119b24.gif

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I don't know you nearly well enough to infer that you are a dunce, mate. You were just writing nonsense - something most of us are guilty of at times.

No photo of the Morningstar interface, but it shows max amps as 7.6x (8 I think). I admit, it has not been calibrated, but that figure jives with the plated output of my two old panels. 

Don't get too tied up with MPPT. You probably don't need it.

SolarWorld_80W.jpg

Siemens_55Wcropped.jpg

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My parental units have been visiting this weekend so I haven't had the opportunity to perform any tests or install the new, PWM controller.

I don't have a "dead" battery to test on, in any case. The best I can do, is flip on all the loads. I think the fridge, engine blower, bilge pump and fresh water pump will put draw over 10 amps, combined.  Will that be sufficient?

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9 hours ago, Ajax said:

My parental units have been visiting this weekend so I haven't had the opportunity to perform any tests or install the new, PWM controller.

I don't have a "dead" battery to test on, in any case. The best I can do, is flip on all the loads. I think the fridge, engine blower, bilge pump and fresh water pump will put draw over 10 amps, combined.  Will that be sufficient?

yes, if you can draw about 10 amps, that should be enough to get the system running, i get about 10 amps of output with the charge controller showing 150Ws.  Should be enough to at least test the system further.

 

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On 5/29/2019 at 4:16 PM, Joakim said:

Yes just for the test to see can you get 7-8  A out of the panel as you should (no shadows and directed towards the sun). You can put all power usage on to lower the voltage and enable the whole 7-8 A current to be taken at normal charging voltage. I have just 50 W panel and putting navigational lights on is enough for testing it. Only tricolor is LED. I get 4 A from other navigational lights.

Ok, I performed some tests.  Today was ideal solar conditions: 0% cloud cover, a high temperature of 77F. I oriented the panel perfectly towards the sun.  I'm using a Fluke 77BN multi-meter.  I do have a clamp-on meter coming in the mail.

  • First, I eliminated 11 feet of excess wiring.
  • Next, I re-measured the raw panel output across the disconnected wires at the end of the run:  127.75 watts- 17v and 7.5 amps output. (yes, I'm rounding a few tenths.)
  • Next, I re-connected the Victron to the panel and a nearly full battery and checked the solar output via Bluetooth: 28 watts (13.7v and 2.1 amps)
  • Next, I flipped on enough loads to draw 12 amps and re-checked the Victron:  33 watts was the most I saw. (12.9v and 2.6 amps)
  • Next, I removed the Victron from the circuit and directly connected the panel to the battery, with 12 amps of load. Measured at the battery terminals: 12.8v and 4.8 amps
  • Finally, I added my Chinese PWM controller and re-measured, with 12 amps of load: around 12.8 and 4.8 amps, very slowly dropping because I was pulling 12 amps. (The same as the directly connected panel?!?)

The last two bullets seem to tell the story-  The panel output when connected directly to a loaded battery seems low. It's low enough that the Chinese controller (rated for 20a)  simply let the full output of the panel flow right through it, to the battery.

The Victron tech seems correct. The loaded panel output voltage isn't high enough to really drive the Victron controller properly. He says the controller likes to see 5v difference between the battery and the panel and I never really get that.

The PWM controller nearly doubled my amps to the battery over the Victron. Still, when the panel was directly connected to the loaded battery shouldn't I have seen more amps than 4.5?  The panel is rated for 8 amps.  The voltage also seemed low. 

Bottom line, it seems like the most I can get out of my 125 watt panel now, is 61 watts, whether I'm directly connected or through the PWM controller.  I don't expect 125 watts but 61 watts under ideal sun seems low.

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Nice report!

On your test setup where is the Fluke set up to measure amps?

The open circuit voltage and the short circuit current at the panel are below spec, aren't they? Maybe the panel isn't getting irradiance to test spec or maybe it's a bit weak? Panels are rated at MPP and both the voltage and current will be lower there than Voc and Isc.

My back of the envelope WAG (<== for real, this is very speculative) suggests to me that your panel should be producing  something south of 77 watts at MPP based on your Voc and Isc and extrapolating from the spec MPP. Based on that very sketchy guess, with the panel at battery voltage 61 watts seems reasonably consistent with your Voc and Isc.

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Open voltage is very low. Could there be a few cells in short circuit? There really shouldn't be much difference between short circuit current and current at 12.8 V. 

PWM charger should be just the same as directly connected panel as long as battery voltage is not too high and needs regulation.

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8 hours ago, weightless said:

Nice report!

On your test setup where is the Fluke set up to measure amps?

I touch the panel leads directly to the battery posts,  and touch the meter leads to the battery posts.

The open circuit voltage and the short circuit current at the panel are below spec, aren't they? Maybe the panel isn't getting irradiance to test spec or maybe it's a bit weak? Panels are rated at MPP and both the voltage and current will be lower there than Voc and Isc.

My back of the envelope WAG (<== for real, this is very speculative) suggests to me that your panel should be producing  something south of 77 watts at MPP based on your Voc and Isc and extrapolating from the spec MPP. Based on that very sketchy guess, with the panel at battery voltage 61 watts seems reasonably consistent with your Voc and Isc.

It sounds like you're saying that this is (roughly) normal output. If so, I have greatly underestimated the expected output of this system.

 

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6 hours ago, Joakim said:

Open voltage is very low. Could there be a few cells in short circuit? There really shouldn't be much difference between short circuit current and current at 12.8 V. 

PWM charger should be just the same as directly connected panel as long as battery voltage is not too high and needs regulation.

They do seem the same. It's as if the PWM charger is passing the full output of the panel through to the battery because it is safe to do so with 12 amps of load.  If the panel is defective and not putting out the proper voltage, I have no way to test individual cells. There's nothing I can do except replace the panel.

Oh, I performed a few other less scientific tests:

With the PWM controller connected, I reduced the load on the battery to just the fridge, which is 4.5 amps. I measured nearly 12.95v and 5 amps at the battery and very slowly climbing, which seems to indicate that with the PWM controller, I am getting better output and the system is now just able to overcome the load of the running fridge under good solar conditions whereas I never even came close with the Victron controller.  This seemed to confirm that my amperage readings were accurate in my original tests in post #40.

The PWM controller I purchased for these tests only indicates charging voltage, no amperage readings are available without putting a meter on the battery or controller terminals.

I apologize for repeating myself but as I said, I'm now getting 2X the power output by using the PWM controller (which is good) but I am still unsure that the panel is producing the proper loaded output. 

My Tesla home array is rated at 8.6Kw and I've seen it produce 7.5Kw which is what... only 16% difference between "optimal" and real world output?  The Solbian panel real world output is around 50% less than its rated output whether directly connected to the battery or through the PWM controller.  I realize these are totally different systems but this seems like an excessive reduction to me.

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59 minutes ago, Ajax said:

On your test setup where is the Fluke set up to measure amps?

I touch the panel leads directly to the battery posts,  and touch the meter leads to the battery posts.

Weightless was asking specifically about current measurement. Not sure if I am misunderstanding what you wrote, but if your DMM is set to DC amps range and the leads are in the correct terminals (COM and 10A in your case), you'll only do that once on the battery. As it's a Fluke, you would immediately blow the fuse. A cheapo meter would melt/smoke/explode. You may just get away with it across the panel leads measuring short-circuit current - which may help determine the proper functionality of the panel itself.

Always be extremely careful with a test meter configured for current readings. It is basically becomes the opposite of the high impedance load it presents when in voltage mode.

(Apologies if I am underestimating your skills!)

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9 minutes ago, seabell said:

Weightless was asking specifically about current measurement. Not sure if I am misunderstanding what you wrote, but if your DMM is set to DC amps range and the leads are in the correct terminals (COM and 10A in your case), you'll only do that once on the battery. As it's a Fluke, you would immediately blow the fuse. A cheapo meter would melt/smoke/explode. You may just get away with it across the panel leads measuring short-circuit current - which may help determine the proper functionality of the panel itself.

Always be extremely careful with a test meter configured for current readings. It is basically becomes the opposite of the high impedance load it presents when in voltage mode.

(Apologies if I am underestimating your skills!)

Yes, that was how I measured DC amps. The meter is rated for 10 amps and I never measured greater than 7.5 amps across the disconnected wires of the panel.

Wait....Ooooohhh, I see what you're saying. Like I said, I placed the solar panel wires directly on the battery posts, then I connected the meter to the battery posts. Holy shit. How the hell did I not blow the fuse in my meter when measuring DC amps across the battery?

Where the hell was I supposed to measure solar panel output when it was directly connected to the battery, then?

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@seabell Aw, crap. I had the leads in the wrong place on the meter when measuring the current!  I knew I was tired when I started fucking around with this.

Oh, my clamp-on meter arrived late last night, so I'll repeat these tests this afternoon.

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Current measurements are made in series with the source or lod to be measured. Here's the relevant diagram from the manual for your meter:

image.png.f07eb7d27db54a6e450e160e5fd4b337.png

Your panel is represented by the circle with the squiggly line (it really is an AC source in the diagram, but procedure is similar). The zig-zaggy thing at the bottom represents either your controller or your battery, depending on where you break the circuit.

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3 minutes ago, Ajax said:

@seabell Aw, crap. I had the leads in the wrong place on the meter when measuring the current!  I knew I was tired when I started fucking around with this.

Oh, my clamp-on meter arrived late last night, so I'll repeat these tests this afternoon.

What's your clamp rated for? They are notoriously inaccurate, particularly at low loads, so will not be as accurate as using your meter - or a shunt for higher amperages.

 

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Just now, seabell said:

Current measurements are made in series with the source or lod to be measured. Here's the relevant diagram from the manual for your meter:

image.png.f07eb7d27db54a6e450e160e5fd4b337.png

Your panel is represented by the circle with the squiggly line (it really is an AC source in the diagram, but procedure is similar). The zig-zaggy thing at the bottom represents either your controller or your battery, depending on where you break the circuit.

Right. I had the red lead plugged into the voltage socket the whole time even though I spun the knob from Vdc to Amps DC. Fuck, kill me now.  Well, it saved me from blowing the fuse and now I have a clamp meter, so I'll run the tests again this afternoon. God. Damnit.

I bought this meter, which was recommended by @valis who is a pretty wise member here.

https://www.amazon.com/gp/product/B00O1Q2HOQ/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&amp;psc=1

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That'll certainly be helpful. I bought the exact same model a few years ago. It was binned after the batteries leaked. Take them out as soon as you think you won't be using it for a while, and, if keeping it on the boat or near the sea, a ziploc for storage may help it last a bit longer. 

Don't worry about your mistake. You learned something, right? That's a good thing.

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14 minutes ago, Ajax said:

Fuck, kill me now.  Well, it saved me from blowing the fuse

I supervise a gang of young chaps that our company calls 'technicians', though few of them have much formal electrical training. We teach them procedures in-house, and I issue them with DMMs that specifically DO NOT HAVE current ranges - just to keep them out of trouble. We keep one Fluke 287 for when high accuracy (or current) measurements are needed, and I have taped over the A/mA terminals really as a reminder that they are not supposed to connect the test leads there normally. Fluke fuses, like everything else they sell, are costly.

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30 minutes ago, Ajax said:

Right. I had the red lead plugged into the voltage socket the whole time even though I spun the knob from Vdc to Amps DC. Fuck, kill me now.  Well, it saved me from blowing the fuse and now I have a clamp meter, so I'll run the tests again this afternoon. God. Damnit.

I bought this meter, which was recommended by @valis who is a pretty wise member here.

https://www.amazon.com/gp/product/B00O1Q2HOQ/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&amp;psc=1

Measuring DC current with a cheap clamp-on is pushing the envelope. Not that it won't work, but make sure you zero the meter in about the same position and orientation as it'll be when you make the measurement and immediately before you clamp it on. Don't expect much better than 50mA repeatability, but that's fine for what you're doing. 

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Speaking of fuses...  Do you have a fuse inline to the panel?

I helped debug a low output situation for a friend, and it turned out to be a bad fuse holder.  The fuse was inside an MC4 style connector.  It was stamped for the amperage he bought, but the replacement had a much larger cross section filament. 

I'd get things up on a sunny day and either by hand go around every inch of the system and feel for heat, from the panels to the wiring.  The tell for the fuse holder, was it was sitting in the shade of the panel but warm to the touch compared to everything else.  

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19 minutes ago, IStream said:

Measuring DC current with a cheap clamp-on is pushing the envelope. Not that it won't work, but make sure you zero the meter in about the same position and orientation as it'll be when you make the measurement and immediately before you clamp it on. Don't expect much better than 50mA repeatability, but that's fine for what you're doing. 

I agree that it'll be accurate enough for what I'm trying to prove. Milliamp accuracy isn't needed when I might be missing several, whole amps.  Of course...I might not be missing any amps at all! LOL...

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16 minutes ago, Zach said:

Speaking of fuses...  Do you have a fuse inline to the panel?

I helped debug a low output situation for a friend, and it turned out to be a bad fuse holder.  The fuse was inside an MC4 style connector.  It was stamped for the amperage he bought, but the replacement had a much larger cross section filament. 

I'd get things up on a sunny day and either by hand go around every inch of the system and feel for heat, from the panels to the wiring.  The tell for the fuse holder, was it was sitting in the shade of the panel but warm to the touch compared to everything else.  

No fuse holder...but now that you bring it up, perhaps I should install one...  after I sort all of this out. No sense introducing new variables at this point.

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Ajax, hope you won't be offended if I post this gentle intro to current measurement. It might help others, and that's what we do in Fix It Anarchy, right?

 

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@seabell  No, I don't mind.   This was more a case of fatigue and "haven't done this in awhile, so I forget" rather than "didn't know."  Always good to have a refresher. I am new to using clamp-on, inductive meters though.

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His video on how to correctly use the clamp meter was helpful, and I'll try that out in a few hours.

Oh-  I'm also in the process of installing a Balmar SG200 battery monitor. Since that uses a shunt, it should accurately display current flowing into and out of the battery.  Space is tight though, so it's taking a bit of time.

 

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5 hours ago, Ajax said:

 

It sounds like you're saying that this is (roughly) normal output. If so, I have greatly underestimated the expected output of this system.

I hope I didn't add to the confusion. 

To be clear, I think  you should be getting more power out of the panel. Particularly, you should get a higher open circuit voltage. There is a problem. It might be that the panel is not getting enough light. A little bit of shading can make a big difference. It might be that the panel has a fault.

If you have another panel aboard that you know the specs for if its open circuit voltage and short circuit current are at or close to spec then you have good light.

I would visually inspect the panel. Look for hairline cracks in the cells, for discoloration around the joints where the flat metal connectors cross and for bubbles of delamination on the back. Joakim posted what looks like a very comprehensive guide if you want to take a really deep dive into this.

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@weightless and @Joakim and @seabell

Ok, now that I have my head out of my ass WRT measuring current, here's an update:

All earlier voltage measurements still stand as presented.  Current is actually around 3.5 amps with the panel directly connected to the battery and also as output by the PWM controller. Although my earlier current numbers were wrong, the behavior is still the same; The PWM controller is simply passing all of the amps that the panel is producing straight to the battery because the load is so great and the panel output is so low.

I measured with my new clamp meter and also with my Fluke meter and got the same numbers.  I also completed my Balmar SG200 installation and got the same numbers with that, although not to the same number of decimal places because it doesn't offer that level of resolution.

Just to be clear about how I measured current this time (since I screwed it up the first time)-  I connected the solar panel wires directly to the battery posts. I then clamped the meter to a single solar panel wire in an orientation that gave me a positive current reading.  I did the same when I connected the wires to the PWM controller. When I used the Fluke, I moved the red test lead over to the 10a socket in the meter and placed the meter between one solar panel wire and one battery post. (Look mom, no smoke!)

Solar conditions were not as good yesterday and I had to wait for holes in the clouds to watch the numbers climb. Conditions are forecast to be poor for the next several days so it might be awhile before I have conditions as good as my first day of tests, but I'd like to perform the tests one last time when it's really sunny.

Bottom line: Now that I have my current readings straight, I think the panel has a problem.  If the best output I can get when directly connected to a battery loaded with 12 amps is 3.5 amps in full sun, something isn't right. Whether directly connected or pushing through the Victron or PWM controller, I never get anywhere near 7 or 8 amps.

There is no sign of any damage, bubbling or discoloration. There is a blocking diode on the panel... I can check that. I can disassemble and inspect the MC-4 connectors.  I have already shortened the wire run to the shortest I can make it, which is about 17-20 feet.

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I couldn't quite understand how did you measure before? How could you get 2.1, 2.6 and 4.8 A measuring some other than the correct way?

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3 hours ago, Ajax said:

Solar conditions were not as good yesterday and I had to wait for holes in the clouds to watch the numbers climb. Conditions are forecast to be poor for the next several days so it might be awhile before I have conditions as good as my first day of tests, but I'd like to perform the tests one last time when it's really sunny.

I find it hard to judge the quality of the solar conditions just by eye. A few months ago I had a collection of very small panels setup with metering that I was testing for a project. While the big clouds were obvious it wasn't uncommon to see the numbers go down and then look around to find some tiny wisp of high cloud that I wouldn't normally have noticed.

 

 

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55 minutes ago, Joakim said:

I couldn't quite understand how did you measure before? How could you get 2.1, 2.6 and 4.8 A measuring some other than the correct way?

I failed to move the red probe from the V socket to the 10a socket on my Fluke meter. I also (like a dumbass) measured across the battery terminals. Those values are totally useless.

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I think you almost certainly have a problem using that particular MPPT controller with a low voltage panel. And you are probably right that there is also a problem with the panel, but before you finally conclude it is also the solar panel, I think you should do a direct test with a battery that is not close to fully charged. I know you are simulating that by placing a load on the system, but it adds complexity that is hard to factor in. With the panel connected directly to the battery, you are effectively trying to do constant voltage charging of the battery, and the acceptance current with constant voltage charging drops off very significantly as the battery approaches fully charged. There is always a chance this is just the acceptance rate of the battery at its state of charge that is constraining the current you are seeing. Maybe leave something switched on and running overnight to bring the battery down to a lower state of charge before a final test?

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On 6/6/2019 at 7:08 AM, Ajax said:

Bottom line: Now that I have my current readings straight, I think the panel has a problem.  If the best output I can get when directly connected to a battery loaded with 12 amps is 3.5 amps in full sun, something isn't right. Whether directly connected or pushing through the Victron or PWM controller, I never get anywhere near 7 or 8 amps.

Why not just test it directly then? Disconnect from downstream circuitry and measure Voc (Open Circuit Voltage - should be 20V), and Isc (Short Circuit Current - should be 8.5A) using your meters. It may be useful to do this directly on the panel connectors, then compare to readings where your wires would normally connect to the controller. NB: Don't leave your meter connected in Isc mode for too long - it will probably start getting pretty warm if you do see rated current!

Bear in mind 'insolation' effects due to your ~39 degree latitude. Not sure how significant this is, but if your panel is easily detached you could point it so that it is perpendicular to the suns 'angle of attack'.     http://solarinsolation.org/ 

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2 hours ago, seabell said:

Why not just test it directly then?

I think he has.

I'm still confused about the confusion on the current testing. The first reporting seemed more or less consistent between the test cases to me. That is the Voc and Isc made sense at battery voltage and current. I don't see how those current readings came about with the meter leads in the wrong positions on the meter and the circuit.

Anyway, his Voc, which seems likely to be correctly measured, is low. The season is good for solar where he is now. The actual conditions are hard to know. Some kind of meter or another panel to compare with would probably help.

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You're right, up to a point. Ajax said:

On 6/4/2019 at 9:26 PM, Ajax said:

Next, I re-measured the raw panel output across the disconnected wires at the end of the run:  127.75 watts- 17v and 7.5 amps output. (yes, I'm rounding a few tenths.

...but we're not sure how or even if he measured that current, so it's time to do it again. (Said he was tired, but that's what I say when I've had too much grog.)

Just kidding, Ajax, and we all make dumb mistakes at times, so you can stop beating yourself up about it now. Lesser blokes wouldn't even own up to it, and you're a better man for admitting the error instead of obfuscating and wasting peoples time. Now let's drill down to the root cause of your PV issue.

The figures look wrong, somehow. I doubt you'd see that high an Isc with the rather low Voc you recorded. As mentioned before, if it's not too difficult measure at the panel and then at the end of the feeder wires. That'll be two major components verified (good or bad).

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5 minutes ago, seabell said:
On 6/4/2019 at 3:26 PM, Ajax said:

127.75 watts- 17v and 7.5 amps output.

...but we're not sure how or even if he measured that current, so it's time to do it again.

He did report current readings. I can't come up with a story about how he got 7.5 amps showing on his meter after taking a 17 volt reading that doesn't involve moving the leads on the meter, changing the dial, and shorting the circuit with the leads. Equally, the readings when connected to a battery only make sense to me with a similar test topography. I can imagine lots of other ways those readings could be in error but I am asea on how they could have come about as Ajax described his setup. 

The spec is 20 Voc and 8.5 Isc. MPP is 16V x 8A.

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44 minutes ago, weightless said:

I can't come up with a story about how he got 7.5 amps showing on his meter after taking a 17 volt reading that doesn't involve moving the leads on the meter, changing the dial, and shorting the circuit with the leads. Equally, the readings when connected to a battery only make sense to me with a similar test topography. I can imagine lots of other ways those readings could be in error but I am asea on how they could have come about as Ajax described his setup

Why worry about it? Let it go. Ajax has already 'fessed up and said they are null and void. No need to ruminate on it.

 

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1 hour ago, seabell said:

Why worry about it? Let it go. Ajax has already 'fessed up and said they are null and void. No need to ruminate on it.

 

Because what he "fessed up" to doesn't make sense to me. No only did he get numbers but the panel and loaded numbers he got are plausibly consistent with each other. That shouldn't have happened if he did what I think he said he did. There is still something important getting lost in communication. So, I don't think it's a good idea to assume that we can just move along and get a good result. I mean Ajax may do as he pleases, of course. But as an interested kibitzer I'd like to know what is really going on. 

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Oh boy. Weightless, no offence, but why try to make sense out of nonsense? Just forget it and let's help steer the man to success, eh? (and thanks for the new word. I had to google it. Good one.)

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3 hours ago, seabell said:

Just forget it and let's help steer the man to success, eh?

I wish him the best of success, always. I think he's doing a find job of steering. I hope he'll forgive my backseat driving.

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I have been out of town for the last 3 days. Solar conditions have also been absolute shit, so no point in testing.

When I get a chance, I'll explain again the mistake I made, and try to take photos. The short summary is:  I did NOT move the probe to the 10a socket on the meter, so regardless of what the meter displayed, I never did measure current during my first tests. It was a totally false reading.

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On 5/28/2019 at 4:44 PM, IStream said:

The manual says it can take up to 10 AWG wire. Do yourself a favor and buy one of these for the ends of the wires:

https://www.amazon.com/gp/product/B073TZ5BBG/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1

It'll make it so much easier and more reliable to use screw terminals like those on the Victron.

 

Quick question - are these designed to be crimped onto the ends and then inserted into the screw terminals? 

Because I hate those screw terminals, such a pain and it never seems to hold the wire correctly so excited if this would help

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Yup, that's exactly how they work. The crimpers come in square and hex flavors but for terminal strips having square holes, the square crimp is preferred. In addition to crimping the sleeve around the wire bundle, the crimper typically puts some serrations on the faces of the terminals so they grip the screw better. It's a cheap investment and worth every penny.

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I have a similar issue with my flexible panel. Gioco 170 w panel, 36 cells, I'm getting much lower amps/watts out than expected. Just an hr ago the clouds started to gather, but I was only seeing 70 watts/ 5 amps @ 15-18 volts.  Victron 15/75 controller. Charging in bulk, and keeping ahead of the fridge and autopilot, but still... New old panel, took way too long to get around to install it, so can't bring it back. I had it sewn in to my new Bimini, and you never know for sure if the panel was damaged from the canvass people bending too much, was buggered from the start or what. 

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I hate to brag but...

I cleaned off my panels and fired up the controller today in preparation for a trip this week. This is the first summer trip with a new 400Ah/12V lithium battery setup. The solar system is two SunPower E-435 commercial panels in parallel for a total of 870W label capacity, running through a Morningstar 60A MPPT controller.

I swung the boom to the side with the traveler to minimize shading at the dock and let 'er rip. She was putting out 600W by 10:30am and peaked at 700W output around 12:30pm. After a few hours and about 180Ah, my BMS said "basta!"

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Ok, to follow up:

Nothing has changed with respect to my 125 watt panel.  The most it ever puts out is 2.7-ish amps. Doesn't matter what controller I use, or if I eliminate the controller entirely and connect the panel directly to a loaded battery.

I have just purchased a brand-new, Renogy 160 watt flexible panel that arrived yesterday:  https://www.amazon.com/gp/product/B079HJQBVW/ref=ox_sc_act_title_1?smid=ATVPDKIKX0DER&amp;psc=1

Today is forecast to be very sunny. I figure I'll have it installed by around 3pm and I'll have an entire, sunny weekend to test, so I'll report back on Monday.  I'm betting I get much better results.

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On 7/1/2019 at 7:04 PM, IStream said:

I hate to brag but...

I cleaned off my panels and fired up the controller today in preparation for a trip this week. This is the first summer trip with a new 400Ah/12V lithium battery setup. The solar system is two SunPower E-435 commercial panels in parallel for a total of 870W label capacity, running through a Morningstar 60A MPPT controller.

I swung the boom to the side with the traveler to minimize shading at the dock and let 'er rip. She was putting out 600W by 10:30am and peaked at 700W output around 12:30pm. After a few hours and about 180Ah, my BMS said "basta!"

What the hell are you powering with all of that?  Do you have a water maker?

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Thanks for a great thread. Discovering ElectroBOOM was just icing on the cake. Good luck this weekend!

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I've purchased Renogy and several other discount brands of solar panels and NONE of them has come close to stated output.   Just bought a Sunpower branded 110W panel.   It puts out the 5.3A base and I get 7A with the Victron MPPT controller.

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@solosailor  Hmmm...the purchase price may have been too good to be true...we'll see.

I did test the new Renogy panel out yesterday in the late afternoon. The results were excellent.  I re-installed my Victron MPPT controller (because it reports much more information than my cheap-o PWM controller). 

In sub-optimal sun angles, I saw 96 watts max, with an output of 7.1 amps and 13.5 volts on the output side of the controller.  The input side showed 18-ish volts at 5.3 amps. This totally blows away my 125 watt Solbian panel @ 2.75 amps max output and seems to confirm that the Solbian panel is faulty in some way.

7 amps is more than my fridge, VHF, plotter, speed/depth and auto pilot all draw, combined. I guess the only downside is that the Renogy panel might have a short service life. If it fails prematurely, I'll probably buy a "hard" panel from a more reputable vendor.

Sunpower is a trustworthy name?

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Sunpower makes the highest efficiency cells, by far.   These are the cells Solbian uses.    Many "low cost" suppliers state they use Sunpower cells but from my experiences they must be using B or C cells.     Sunpower own branded panels are now available in 50W, 100W & 110W panel.   This is the 110W that I just tried.

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