Rednecktek
Solar Wizard
So I'm pondering my options for my cabin and I can't decide if I want 1 system nerfed on panels or do 2 completely different systems. My cabin has an existing 12v system powering lights and heaters and fans, so I MUST retain 12v in there. I'd like to throw an inverter in so I can turn off the generator at night, but I'd want to keep my inverter comparable to the generator I have to make math easier, which means a 2000w inverter and all the fuses and shunts that entails. I have the physical space for 6x 120Ah FLA batteries on the shelf before things start hanging over the edge, 4 installed in parallel now.
I was looking at the specs on my MPPT controller and it says that on a 12v system I can only have a max VoC of 80v and a max wattage of 720w. I'm planning on buying a pallet of used panels for a few projects and they're 36.3VoC as listed which means if I did a 2s I'd be right on the edge of frying my controller when the winter hits. To avoid frying things I'd have to limit it to a 3p setup which would only give me a MAX of 600w. Unfortunately I can't find a max input amps for my controller so I'm guessing that the 21.3a max would still be OK.
So it seems I have to choose between adding 2 batteries and a 12v 2000w inverter OR reducing my 12v bank to 2 batteries and going with an AIO 24 or 48v unit separately to power the 120v systems. I can find 24 and 48v PWM controllers to parallel in to keep the batteries topped up while disconnecting the batteries from the AIO to avoid drain on them for the 6+ months at a time I'm not up there, so that's a thing. It seems to me that going with a separate system for the 120v would be more expensive as I'd be building a complete new system rather than modifying the one I have, but would be safer (less amperage involved), be easier to top up with the generator, and allow larger arrays and more PV input.
Down side is that I can only have 4 batteries involved, either 120Ah@24v or 60Ah@48v and due to finances LiFe's aren't an option at this time so I'm stuck with FLA's and hopefully AGM's (unless LiFe's become significantly cheaper in the next couple years) for the foreseeable future.
So, oh Hive Mind, I ask of you: 1 system or 2?
What I have:
40a MPPT Controller, 20-80VoC input @12v system, 720w max PV
4x 120Ah FLA batteries
2x 100w Poly panels
Pallet of 200w (170w certified) panels (shipping soon)
25a battery charger
I was looking at the specs on my MPPT controller and it says that on a 12v system I can only have a max VoC of 80v and a max wattage of 720w. I'm planning on buying a pallet of used panels for a few projects and they're 36.3VoC as listed which means if I did a 2s I'd be right on the edge of frying my controller when the winter hits. To avoid frying things I'd have to limit it to a 3p setup which would only give me a MAX of 600w. Unfortunately I can't find a max input amps for my controller so I'm guessing that the 21.3a max would still be OK.
So it seems I have to choose between adding 2 batteries and a 12v 2000w inverter OR reducing my 12v bank to 2 batteries and going with an AIO 24 or 48v unit separately to power the 120v systems. I can find 24 and 48v PWM controllers to parallel in to keep the batteries topped up while disconnecting the batteries from the AIO to avoid drain on them for the 6+ months at a time I'm not up there, so that's a thing. It seems to me that going with a separate system for the 120v would be more expensive as I'd be building a complete new system rather than modifying the one I have, but would be safer (less amperage involved), be easier to top up with the generator, and allow larger arrays and more PV input.
Down side is that I can only have 4 batteries involved, either 120Ah@24v or 60Ah@48v and due to finances LiFe's aren't an option at this time so I'm stuck with FLA's and hopefully AGM's (unless LiFe's become significantly cheaper in the next couple years) for the foreseeable future.
So, oh Hive Mind, I ask of you: 1 system or 2?
What I have:
40a MPPT Controller, 20-80VoC input @12v system, 720w max PV
4x 120Ah FLA batteries
2x 100w Poly panels
Pallet of 200w (170w certified) panels (shipping soon)
25a battery charger