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I have 3 arrays of about 300w each, pointed to different areas of the sky on my heavily wooded site. 2 of the three arrays may be insolated part of the day. The arrays are connected to 3 separate controllers, bussed to 8 golf cart batteries. There is enough power to run my chest fridge, my LTE amp and my RV water pump plus LCD lighting for 2 cloudy days, and to keep the batteries from freezing in the winter. I show "charging" on each controller during the day, but the highest amperage going into the batteries during intense insolation around midday in the summer might reach 25 amps. It seems to me that I am losing a lot of power somewhere. Can you recommend mppt controllers (that show amperage and ) that would work together better than my mish-mash of "cheap" (suspected pwm) controllers?
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Having to assume 12 volt system.
Current output falls of fairly fast on poorly aimed and shaded panels. Try aiming all panels the same way during the "intense insolation around midday"2 Kw PV Classic 200, Trace SW 4024 460ah, -
It would not be possible to aim them at the same time...the 3 different locations insolate at different times. Aiming in a common direction at midday would leave 1 set partially lit, and another set in the dark, aimed at trees.
My question is really about mppt controllers... Is there a brand that would work well in this situation?Comment
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Shade is a bad thing for PV. You would need 3 separate MPPT controllers. Sorry but that's the way it is.2 Kw PV Classic 200, Trace SW 4024 460ah,Comment
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I thought so. I have one which claims to be mppt, but I'm not sure, because I have heard that some lower priced ones claim to be mppt, but are really pwm. Is there a way to check, or can you recommend a 20-30amp controller that is mppt for sure but not terribly expensive?Comment
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If it's small, thin, light and has any type of USB out port on it it is likely fake. Unless it allows a minimum of 100 Voc. it's also likely fake.
Look at EPever Brand controllers. They are popular.2 Kw PV Classic 200, Trace SW 4024 460ah,Comment
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My sets of 3 panels are each connected in parallel, offering 12 v to the controller. Would it be possible to connect them in series, offering the controller 36 v to charge a 12v battery bank?Comment
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Since you have 8 golf-cart batteries, I'm assuming you have four 12V strings of them? Assuming those batteries are at least 200Ah each, four strings equals 800Ah, which means optimal charging is really in the >100A range. To generate something like 100A at 12.5V (charging), and assuming you only get ~85% of nameplate production, then what you actually need is
(12.5V X 100A)/85% = 1470W of panels.
Since the shade is an important consideration, how many feet of distance does it take to reach full, unhindered sun? Is it more because of the trees, or more because of property boundarys? If you are considering getting new controllers, then take a look at Epver's high-voltage models, the ones with a 200V limit.
If you purchase some inexpensive high-voltage residential panels, you can wire them in series to cover significant distances. I myself have arrays of four 30V/250W panels in series for 120VDC. That travels 125' to my controller with no detectable voltage drop. You are likely to find that kind of panel locally on Craigslist for just 40-50$ each?
You can use this voltage drop calculator to look at what distances you can travel with what wire.
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You will only be feeding your batteries very low current, if wired in series to a PWM controller. The controller wont charge to any higher voltage than set for.2 Kw PV Classic 200, Trace SW 4024 460ah,Comment
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If I feed 24v into an mppt controller, can it be used to charge my 12v batteries, in parallel to my 12 pwm controllers?Comment
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You can have more than one charging source on one battery bank. Yes, fed 24 volt panels into an MPPT controller to charge a 12 volt battery. Careful there are many fake MPPT controllers. They are cheaply priced and usually small and light compared to the real thing.2 Kw PV Classic 200, Trace SW 4024 460ah,Comment
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Is it okay to mix pwm controllers with mppt controllers feeding the same battery bank?
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No problem. The charging setpoints should be the same, or at last, very close.2 Kw PV Classic 200, Trace SW 4024 460ah,Comment
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