Recommendations for Off-Grid Non-Portable Overall Specs ??

[DixieMtCR]

I currently have 13 (1300w) mono panels feeding 3 40A MTTP CC's, 8 100Ah lead acid deep[ cycle RV 12 batteries in Parallel, and a 12v/3000w PSW Inverter. When the sun is shining, the CC's put out a combined 85amps. All of that is connected to a 10-circuit 30amp manual transfer switch that is capable of feeding 10 circuits in the house, all 120Vac. We live in the woods, in old growth timber, and we only have sun solidly on the panels for about 4hrs this time of year in Feb. That equates to + or - 4.7Kwhr per day.

I am interested in changing to either 24v or 48v battery configuration. And, because I will need to get a new inverter and possibly charge controllers for either configuration, I think I will go with a 4000w PSW inverter. With a 30a transfer switch, i want to be able to deliver the 3600w max. Probably will never run full bore all the time. But my 3000w will not handle max.

Any recommendations for trade off with 24v or 48v system? 100w panels vs 320w panels. wifi enabled system monitor.

 

[acdoctor]

Batteries in series is always best. Parallel can have balance issues, you are probably aware of this with 8 in parallel. 24 volts will get you 4 in parallel. Most solar battery manufacturers recommend a max of 3 parallel strings.
So 24 volt stuff like breakers buss bars and the like is less expensive than 48 volt. But 4 kw inverter should be 48 volts to keep amps down.
4000/48=83.3 amps x 1.15 = 96 amps. And 2 series strings of batteries.
48 volts x 200 Ah = 9600 watts / 2 depth of discharge = 4800 watts. Unless 3600 watts is surge from motor start you may be under batteried. But your solar panels won’t keep up with any more battery.

 

[DixieMtCR]

Batteries in series is always best. Parallel can have balance issues, you are probably aware of this with 8 in parallel. 24 volts will get you 4 in parallel. Most solar battery manufacturers recommend a max of 3 parallel strings.
So 24 volt stuff like breakers buss bars and the like is less expensive than 48 volt. But 4 kw inverter should be 48 volts to keep amps down.
4000/48=83.3 amps x 1.15 = 96 amps. And 2 series strings of batteries.
48 volts x 200 Ah = 9600 watts / 2 depth of discharge = 4800 watts. Unless 3600 watts is surge from motor start you may be under batteried. But your solar panels won’t keep up with any more battery.

Thanks for the info. Much appreciated. I am hoping to increase the number of panels. I want to be able to power all the 120v circuits in the house, continually. Today I had everything turned on solar for 7 hours and used 3.060KWh, In that time period, the solar made 4.300KWh. I turned the solar circuits off at 7hrs because shade from the trees was beginning to shadow the panels and I wanted everything topped off for the night in case the power goes out. We lose grid power up here often. We have had about 100hrs this season where the grid power was out. 39hours in one stretch, temp in the teens and 20s, and 18" of snow for weeks.

At night we really only need a few LED house lights and the wood heater fan. And of course, the crazy inverter draws 2.5 amps under no load. Days, we want to make do with the 3600w (30a) capability of the transfer switch from the solar. very seldom would we do more than that on the 120v circuits