Best solar panels for the buck

[FourPoints]

We're getting ready to put the boat on the hard for the hurricane season. What to do with the panels? We'll leave them in place, but should we cover them to prevent collection or simply disconnect them from MPPT controller and let them sit at Voc? We're afraid to leave them in operation without any load whatsoever for fear of overcharging our 4 golf cart batteries.
Pete

I would leave them hooked up and charging. With the temps down there your batteries will self discharge pretty fast (1% per day or more if they are lead acid). The MPPT controller should keep the batteries sitting at float level which won't hurt them, particularly since they won't be getting any charge overnight.

 

[Bill Roosa]

Hey all
been working on a DIY MPP controller when I realized that you are going from 90 to 95% improvement with this technique.
If you have active aiming of the solar panes you can get a 50% improvement in power output easily. given the magnitude of the increase I'm thinking I'd be investing in a two axis actively aimed panel over the use of MPP.
After looking at the "solar stik" I got the idea of making a controller that would drive two motors (altitude and azimuth). As it turns out this is a really simple (and cheap) circuit.
If any body wants the specifics let me know.

 

[Sumner]

...The MPPT controller should keep the batteries sitting at float level which won't hurt them..

I agree with the above and our Mac sits on the trailer outside with 200 watts of panels hooked up and on the MPPT controller and seems to be doing well.

I'd maybe consider unhooking one (I believe you have 2 210 watt panels) and covering it with plywood or something just to avoid possible damage. We will be in the same fix soon and we have 6 80 watt panels. I'm thinking about maybe leaving 2 hooked up and disconnecting the other 4 and covering them for protection. I could pull them and put them in a small storage unit we rent, but feel I might possibly damage one by accident while doing all of that.

I'll probably leave them all on to run some ventilation in the boat while we are gone. Still working on that. I did buy a couple voltage sensitive switches/relays on e-bay for about $10 each...

http://compare.ebay.com/like/250889307420?var=lv&ltyp=AllFixedPriceItemTypes&var=sbar

... that you can adjust the voltage point where they turn off and on and might try one of those connected to a couple fans and see how that works. More about it here...

http://www.ebay.com/itm/LOW-VOLTAGE...Parts_Accessories&vxp=mtr&hash=item2a0c78f959

The thing I don't like is the panels seem to change dimensions, length and width, for the same wattage and then won't fit the mounts. I went through that mess once already. We did buy one extra 80 watt to keep just in case we do break a panel.

Let us, me, know what you finally do and how it works out.

Sum

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[Sumner]

..If any body wants the specifics let me know.

I'd be interested. I wouldn't use it on the boat, but we are looking to add a lot of solar to the house. Thanks,

Sum

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[Deadhead]

I Used Wholesale Solar

I just ordered my solar panels Friday. I had an Atlantic Towers arch installed last weekend. I will be mounting 2 Kyocera 135w panels atop the arch and a dedicated Genesun MPPT controller for each panel below the sole in the galley. The controllers are from Bruce Schwab.

The longest run is about 35 feet from the top of the arch through the lazarette to the controller location so I needed to go with #6 AWG wires (sized per ABYC from the equation in Calder). I am wiring the controllers to bus bars and from there about 4 feet to the batteries. Wire/cables are from Genuine Dealz.

 

[mitiempo]

Why 2 controllers - 2 separate banks?

 

[Deadhead]

Separate Controllers

Why 2 controllers - 2 separate banks?

Optimum performance per the recommendation on Bruce Schwab's site:

http://genasun.com/aboutsolar.shtml

 

[Sumner]

Optimum performance per the recommendation on Bruce Schwab's site:

http://genasun.com/aboutsolar.shtml

Since the panels are identical you don't really benefit from the separate controllers. He mentions that near the end...

Therefore, for highest performance, use a separate MPPT controller for each panel or set of matched panels.

You have a "set of matched panels".

Good luck with the install we have been very happy with our solar array,

Sum

[FONT=Arial, sans-serif]============================[/FONT]

Our Endeavour 37

Our MacGregor 26-S Pages

Our Trips to Utah, Idaho, Canada, Florida

Mac-Venture Links

 

[mitiempo]

Optimum performance per the recommendation on Bruce Schwab's site:

I think optimum performance comes from a controller set at the correct absorption voltage for the batteries. Obviously that depends on the batteries but for Trojan T-105 for example they charge quite a bit faster at the recommended voltage of 14.8 than with any controller set at 14.2 - 14.4 as most are. I looked in the Genusun MPPT manual and they do not have a voltage adjustment - they actually don't even state the absorption voltage, only the 13.8 float voltage.

Nobody knows better than the battery manufacturer what voltage is best.

 

[prroots]

We ended up staying at a slip with shore power available. We just decided to disconnect panels from solar controller because our Morningstar MPPT controller was starting each day out in the bulk phase. That doesn't make sense since we have battery charger on continuously. We're afraid of needlessly boiling off liquid from our lead acid batteries. Comments?
Pete

 

[tommays]

My GV-4 keeps on running well and when the battery's are charged it stops BUT

The fact that the Genasun specializes in small controls that max out at the GV-10 140 Watt unit may have a lot to due with there advise

 

[prroots]

Today I called Morningstar about the overcharging issue when running both solar and battery charger. Steve gave, what I believe, is the perfect solution. Turns out the Morningstar Tristar 45 has a custom program option. Just change DIP switches for custom program and run the PC program called MSVIEW to set the absorption time for 1 minute. This means that each morning the controller will only dwell on absorption 1 minute before entering the Float stage. When we leave dock simply switch the DIP switches back and it reverts to the fixed (pre-programmed) mode with longer absorption phase. BTW, the custom setup wizard has hundreds of variables that can be set, but I just changed the one.
Pete