48V System advice

[Bruce E]

Hi, I'm new to solar power and live in a part of the country that is not known for a lot sunny days, except maybe during the height of Summer. Not likely to ever be grid-tied, but want a reliable solar back-up system to run a refrigerator and power-vented hot water tank during outages. So I bought the 48v, 3kV Growatt All-in-one and two, 24v BB batteries to hook in series. Asking for advice at this point on which ground-mounted panels and racks and wire sizes/connector type to go with back to the Growatt inverter. From what I've read so far, I need perhaps 1000 watts minimum of panels, and 48 volts, correct?, so would wire say 4-250w, 12v panels in series. Just not sure if this is best option. Went with the old "buy once. cry once" adage on the Battleborns, but need to taper off on the rest of system, if possible, from here on out, many thanks.

 

[Craig]

Best bet is to look on Craigslist for good higher voltage panels. I'm not sure of the growatt maximum input spec. But try and series your panels to reach as close to the SCC max input Voltage with a reasonable margin. If you have a low Sun area I would use at least 2000 Watts of panels if not more. My standard is get as much power as you can any time you have Sun.

 

[JayM]

I have 2 of the Growatt inverters in 48v on the system I am planning.

You need to watch your input volts as well as your input watts, and allow for some breathing room on maxing either of them out.

http://www.growatt-america.com/show-9-589.html says max input voltage is 145v

With my 335w Q-Plus panels, I can only string together pairs of 2, because the panel VOC of 46.81x2 is 63.62 then x the NEC allowance of 1.25 and then the additional x1.25 for really cold mornings and I am near max....

 

[Bruce E]

Thanks, still looking around for panels on Ebay and Craigs List. Not sure about panel voltage, I see most panels are 12v, is it best to use these or get panels that arehigher voltage. Also, how much better is mono vs poly panels for low sun, and cloudy areas, seems the more I read the more I see they produce similar output.

 

[Steve_S]

Check out https://www.santansolar.com/ many people are buying new & used from them and are very happy and their prices are awfully good.

 

[Daniel todos]

Thanks, still looking around for panels on Ebay and Craigs List. Not sure about panel voltage, I see most panels are 12v, is it best to use these or get panels that arehigher voltage. Also, how much better is mono vs poly panels for low sun, and cloudy areas, seems the more I read the more I see they produce similar output.

San Tan solar.com Gilbert az

 

[NotTesla]

If you're working with limited sun days and a dwindling budget, perhaps look into fabricating an 'X' or possibly dual axis tracking mechanism for the panels that you already have in order to maximize their potential. Depending upon the type of cells it could add as much as 40% to your output. Check out Instructibles site. All sorts of bright folks posting creative DIY's there. Also consider adding a wind turbine or three. Check out John Daniel on Youtube for some good guidance on small systems.

 

[JoeHam]

Definitely skip the 12v panels and go higher wattage.

Combine as needed to get over 100 voc which is likely closer to the sweet spot of your MPPT.