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zzrider

Finished upgraded solar system

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Finally finished upgrading my solar arrangement.  Dual 100w Renogy Eclipse monocrystaline panels, each feeding its own Genasun MPPT controller.  Controller output switchable; can be combined to feed one bank, or split to maintain separate banks. 20180613_111437.jpg.356370b4ec7d52da13556f9e36d8a248.jpg

20180613_164236.jpg.7f2b981ada099f94597d201c71357d39.jpg20180605_191230.jpg.707a7776dca83ca317bff2dce984469e.jpg

On to the next project...

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Nice.  Be sure to protect those exposed house battery lugs -- something shorting across the washers would be a very bad thing.

I did something similar for my three 100W panels.  I now have three of the Genasun MPPT controllers, and some monitoring.  It's a bit of a science project, but works quite well.  (It was nearing sunset when I took the picture).

Monitor 1.jpg

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Valis - already addressed that. The terminal posts are capped with nylon washers & acorn nuts.

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4 hours ago, zzrider said:

Valis - already addressed that. The terminal posts are capped with nylon washers & acorn nuts.

OK, I couldn't tell that those were nylon washers and nuts, washers presumably larger in diameter than the lugs underneath.  You've got a regular nut and washer torquing down the lug, right?  If so, it sounds pretty good.

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Good work guys. But seriously, on a yacht ya gotta clock the screw heads.

From who does one get those little V/A readouts?

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4 hours ago, daddle said:

Good work guys. But seriously, on a yacht ya gotta clock the screw heads.

From who does one get those little V/A readouts?

 

Little multimeter

They are far from weatherproof so I'd only mount them where they can't get wet.  Not sure how long they'll last but for the price I don't really care.  Have one that's still working after 2+ years.

 

Edit:

Yacht? Wassat?  I have a money-gobbling hole in the water.

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36 minutes ago, zzrider said:

Little multimeter

They are far from weatherproof so I'd only mount them where they can't get wet.  Not sure how long they'll last but for the price I don't really care.  Have one that's still working after 2+ years.

Yep.  They are also not particularly accurate.  I ordered some extras for my little panel project, and ended up sorting them for best match and accuracy on the voltage display.  I was seeing +/- three tenths of a Volt difference among the group.  The current indications also disagreed a bit.  But they were good enough for my purposes, which is  to give me a rough indication of the panel performance, and any MPPT gain. 

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Valis - i agree on the accuracy.  I'm seeing 0.2-0.3 variance also.  As you said, good enough for my purpose.

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Bleh! That is the same crummy accuracy as my $200 Blue Seas “instrument”. The Raymarine voltage readout also reads uselessly high. 0.3V is what would inform me there is a failing, and maybe burning, connection somewhere important. What is it with the marine industry and accuracy? Pretty blue LED display though...I’ll buy it! 

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18 hours ago, Max Rockatansky said:

FWIW, I monitor my system with a VictronConnect. Has a dongle and I can view from the phone. Immediate feedback on trends

This - I've used Victron MMPT solar chargers with the bluetooth dongle and it's amazingly easy to check trends from your phone.  Plus the Victron chargers are very programmable, none of the crap "select lead acid, AGM or gel" found on many other chargers.  Not too expensive either for what you get.  From now on, I'm always going to look at what Victron has as a starting point for any charging or monitoring system...

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I agree on the Victron.  I don't have any, but a friend does and it looks like great stuff.  I just felt like going old-school with my project, but for trend monitoring and good diagnostics (and apparently excellent MPPT performance) the new Victron seems like an excellent solution.

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Newb question. Why use a separate controller for each panel?

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Increased output.   If one has any shaded areas the panel in full sun is still going full tilt.

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6 minutes ago, solosailor said:

Increased output.   If one has any shaded areas the panel in full sun is still going full tilt.

You don't need separate controllers to achieve this, just wire the panels in parallel. 

I think the main advantage to the multi-controller approach is redundancy. What you give up with Genasun (the most common panel-dedicated controller) is programmability, remote monitoring, and system integration if your charge controller is part of a larger network of chargers, inverters, and the like from the same company.

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That doesn't solve the problem as the MPPT's can only average what the whole panel sees, parallel or not. The worst case is basically half the panel in full sun, half the panel in full shade, panel is outputting below 50% max power as the shaded section is drawing the voltage lower than if those cells were gone (in a good panel design the current impacts are minimal). Beyond that time to recover isn't zero when the full panel receives sun again; I haven't looked at the specs on some of the MPPT's listed in this thread, but I highly doubt they match what we are using.

Anyway, in an ideal world each cell would have its own MPPT to keep the whole array operating at near peak efficiency under different lighting conditions where each cell may not be illuminated the same as its neighbor.

Cool to see all these systems getting implemented, something I would like to add to the boats I race on as running the diesel offshore when there is plenty of sun is absolutely brutal in terms of heat and noise.

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On 6/28/2018 at 12:55 PM, Mizzmo said:

Newb question. Why use a separate controller for each panel?

I did it primarily for redundancy and flexibility.  With a 3-way switch downstream of both controllers, I can send the output of either controller to either house or start batteries.  

I've also read that dedicating a controller for each  panel does extract max efficiency from the panels if there is partial shading on one.  I understand IStream's point about wiring multiple panels in parallel to a common controller.  I don't have enough experience to make a definitive statement, but I figure having a controller for each certainly doesn't hurt.

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You can wire parallel to single controller, but redundancy is nice, and in my case it actually happened to be cheaper to buy a couple smaller controllers than one that was large to handle the multiple panels

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This question (parallel panels vs independent MPPT controllers) is one reason I went with three controllers.  I do see that the three controllers occasionally run the panels at somewhat different voltages, depending on backstay shadows, dirt, etc.  There doesn't seem to be enough difference to result in a big power conversion advantage, but I'll bet I get a couple % improvement. I should study this more.

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Regarding the subject of independent controllers for each panel vs. one controller servicing multiple panels, Genasun has an interesting article about this specifically referencing solar on a boat:

Quote

Solar systems for watercraft are different, and may look completely different from boat to boat.  Given variation in hull design, masts, rigging, cockpit arrangement, deck angles, and aftermarket customizations, there are very few standard surfaces on any boat.  Moreover, it is rare that any of these surfaces experiences the sun in precisely the same way as the others at any given moment. Each solar panel deployed across these varied surfaces will have a different angle of incidence, different shading, and even different sizing than each of the other panels in the system. No single charge controller on such a system will deliver the maximum power possible to your batteries at any time–even in the fairest of weather.  The constant motion of the boat, passing clouds, and irregular shadows caused by the rigging and structures of the vessel will hamper the system’s ability to reach its potential, every time.

These unique problems require a different approach to solar system design.  Since the panels will be operating under different conditions, they will have different optimum operating voltages (the “Maximum Power Point” or “Vmp”).  The conventional approach of connecting all panels to the same charge controller would force them to operate at the same voltage, preventing them from reaching their potential.  Instead, the optimal solution is to pair each panel with its own smaller and faster maximum power point tracking (MPPT) controller. When managed by its own MPPT controller, each panel will deliver the most power possible at any given moment, even with overcast skies, intermittent partial shading, or low-angle light.  

With a small system and inexpensive controllers, I figure every 10th of an amp I can wring out of my panels is worthwhile.

I do notice the output of my two controllers varying wildly from moment to moment as the boat moves around, so there appears to be some truth to this.

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18 hours ago, zzrider said:

Regarding the subject of independent controllers for each panel vs. one controller servicing multiple panels, Genasun has an interesting article about this specifically referencing solar on a boat:

With a small system and inexpensive controllers, I figure every 10th of an amp I can wring out of my panels is worthwhile.

I do notice the output of my two controllers varying wildly from moment to moment as the boat moves around, so there appears to be some truth to this.

Unconsidered in that article is the effect of controller output mismatch. In the real world, one controller's 13.7V output won't necessarily be the same as another's. How much of a difference there makes a difference to the batteries? How about differential voltage drop across different length wire runs from the controllers to the batteries? A single  controller with a voltage sense wire can optimize the charge voltage pretty well. Multiple controllers with different runs having different lengths and with different sized panels are a different matter. In short, I think it's entirely possible that having multiple controllers does a better job of optimizing panel power output and a worse job of actually using that power to charge the batteries.

I'd really like to see some data from well controlled experiments comparing different installations of parallel panels with a good, fast-MPPT single controller equipped with a sense wire to independent panels with multiple controllers. 

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Thanks for all the detailed replies. Interesting stuff

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