Is this a good deal?

[ladycage]

Hello All,

I am a beginner and just getting started trying to build a small but expandable solar system. Someone I know is selling 140W 65V used solar panels for $50 each. The panels are rigid, mono in Georgia. I have a 12v 100ah lifepo4 battery and a 100v/80A mppt controller, 3000w pure sine inverter. I currently also have a EcoFlow Delta mini. My question is will the panels work with my equipment or would I need to get a 48v battery?

Is it wiser to use high voltage panels or lower voltage? If I understand correctly higher voltage charges the battery faster but risk overcharging?

Thanks for your help.

 

[Mattb4]

You say your MPPT controller is rated for 100 PV max volts and 80 battery charging amps. If the panels you are looking at are 65Voc than you can not do 2 in series as that will exceed the max voltage. So you must wire in parallel. With 65Voc the panel is likely around 2.5amps at Imp. Each panel you put into parallel will add amps. Since your batteries are 12v and the charger is 80a that means the max wattage for the panels could be 960w. 960w/60v = 16a So total panels in parallel can not exceed 16a. 16a/2.5a/panel=6.4 panels or just 6. Using 6 panels in parallel thus gives you 65 Voc at 15 amps or 140w X 6 panels = 840w array. This limits your battery charging current down to 70a.

This is just a guess based on what you gave me and you would want to look up your SCC input PV amperage rating.

Higher voltage panels can reduce wire size due to lower amperage but they do nothing to change Watts = Volts X Amps
MPPT SCC control battery charging based on design for working with a higher voltage range and reducing it to battery voltage. Generally you need a minimum PV voltage amount that is part of the SCC ratings. Obviously that will be higher than battery voltage.

 

[ladycage]

You say your MPPT controller is rated for 100 PV max volts and 80 battery charging amps. If the panels you are looking at are 65Voc than you can not do 2 in series as that will exceed the max voltage. So you must wire in parallel. With 65Voc the panel is likely around 2.5amps at Imp. Each panel you put into parallel will add amps. Since your batteries are 12v and the charger is 80a that means the max wattage for the panels could be 960w. 960w/60v = 16a So total panels in parallel can not exceed 16a. 16a/2.5a/panel=6.4 panels or just 6. Using 6 panels in parallel thus gives you 65 Voc at 15 amps or 140w X 6 panels = 840w array. This limits your battery charging current down to 70a.

This is just a guess based on what you gave me and you would want to look up your SCC input PV amperage rating.

Higher voltage panels can reduce wire size due to lower amperage but they do nothing to change Watts = Volts X Amps
MPPT SCC control battery charging based on design for working with a higher voltage range and reducing it to battery voltage. Generally you need a minimum PV voltage amount that is part of the SCC ratings. Obviously that will be higher than battery voltage.

Thank you so much for your help. Seems like those 140W panels aren't really a good deal for me. I am better off buying 100W 18.7v panels for $99 because I would be able to have 4s4p for a total of 16 panels and 1600W. This option is better and more expandable.

 

[Bvillebob]

Santan Solar has an outlet in Georgia, you can get 250 watt panels for less than $50. I've got 40 of them, they're working great. Look them up.

 

[Wakintx]

Id look for higher wattage panels, seemed a bit high price to me for used panels of that wattage.

 

[ladycage]

Wow I didn't know SAntan Solar had a location in GA, that's great. I looked at them before but the freight expense scared me. Thanks so much for all the help you all have given me. It will really safe me so much money.