Goal of this system is backup power for essential household systems, and a family member's medical device, during our frequent grid outages. It was an excuse to explore an interest in solar power and has also become a fun hobby. Some people collect pet rocks and funko pop figures, some of us build solar power systems.
System specs:
4x 410w ET solar bifacial panels 2s2p
2x LV2424, split phase
1x 230ah Lifepo4 DIY battery, Overkill BMS
1x 260ah Lifepo4 DIY battery, Overkill BMS
1x Victron smart shunt
2x Meanwell 27v 600w power supplies for charging from grid or generator
Class T fuses, bus bars, 2/0 cables, breakers, Ox-Gard, etc.
All mounted on a Harbor Freight utility trailer that I enclosed and built racks on top of for the panels. Each rack holds two panels and is individually tiltable if I want to build the spacer for the rack mounting points.
This system will never go on the highway or be towed anywhere, and wasn't built for that at all. It's only trailer mounted so it can be moved very slowly around the property + cut through some red tape.
Vent fans are 2x 12v automotive fans in series to run directly off 24v nominal DC, controlled by an adjustable thermostat and relay.
Batteries are in a plywood box, insulated with 4" of foam insulation, R14 insulation value. Heat is supplied by ~20w of stick-on heaters on an chunk of scrap aluminum, again controlled by a thermostat. Kept the batteries happy even when 15F outside.
I went with external chargers, rather than use the ones built into the AIOs, because the AIOs are wired split phase for 240v output, and require split phase 240v power input to charge. I wanted to be able to charge from my small 120v only Honda inverter generator.
Improvements planned:
1. Add an electrically insulated cover over the shunt and fuses. I've tossed a tool down on the concrete bags that I use for ballast, and while it wasn't a danger, the potential to create a serious problem was very obvious.
2. Build the spacer mentioned above to tilt panels to something closer to our ideal summer angle.
3. Add more panels to the side of the trailer away from the door, near vertical to be a winter-oriented array + re-orient trailer 90 deg so these panels are facing the winter sun, not the shop.
4. Figure out a better cooling system. Right now it's a pure on/off thermostat, I'd like something that also measures outside temp and doesn't turn on the fans if the outside temp is higher than the inside temp, even if the inside temp is higher than the set turn-on temp. Might look at a tiny air conditioner for active cooling vs. just ventilation. Suggestions welcome!
5. Move concrete ballast outside the trailer. They're a lot of thermal mass and keep the fans running a long time after everything else has cooled down.
6. Switch to 48v at some point. Likely in stages.
Comments, criticism, safety suggestions in particular, etc all welcome.
(Edited to clarify a couple points.)
System specs:
4x 410w ET solar bifacial panels 2s2p
2x LV2424, split phase
1x 230ah Lifepo4 DIY battery, Overkill BMS
1x 260ah Lifepo4 DIY battery, Overkill BMS
1x Victron smart shunt
2x Meanwell 27v 600w power supplies for charging from grid or generator
Class T fuses, bus bars, 2/0 cables, breakers, Ox-Gard, etc.
All mounted on a Harbor Freight utility trailer that I enclosed and built racks on top of for the panels. Each rack holds two panels and is individually tiltable if I want to build the spacer for the rack mounting points.
This system will never go on the highway or be towed anywhere, and wasn't built for that at all. It's only trailer mounted so it can be moved very slowly around the property + cut through some red tape.
Vent fans are 2x 12v automotive fans in series to run directly off 24v nominal DC, controlled by an adjustable thermostat and relay.
Batteries are in a plywood box, insulated with 4" of foam insulation, R14 insulation value. Heat is supplied by ~20w of stick-on heaters on an chunk of scrap aluminum, again controlled by a thermostat. Kept the batteries happy even when 15F outside.
I went with external chargers, rather than use the ones built into the AIOs, because the AIOs are wired split phase for 240v output, and require split phase 240v power input to charge. I wanted to be able to charge from my small 120v only Honda inverter generator.
Improvements planned:
1. Add an electrically insulated cover over the shunt and fuses. I've tossed a tool down on the concrete bags that I use for ballast, and while it wasn't a danger, the potential to create a serious problem was very obvious.
2. Build the spacer mentioned above to tilt panels to something closer to our ideal summer angle.
3. Add more panels to the side of the trailer away from the door, near vertical to be a winter-oriented array + re-orient trailer 90 deg so these panels are facing the winter sun, not the shop.
4. Figure out a better cooling system. Right now it's a pure on/off thermostat, I'd like something that also measures outside temp and doesn't turn on the fans if the outside temp is higher than the inside temp, even if the inside temp is higher than the set turn-on temp. Might look at a tiny air conditioner for active cooling vs. just ventilation. Suggestions welcome!
5. Move concrete ballast outside the trailer. They're a lot of thermal mass and keep the fans running a long time after everything else has cooled down.
6. Switch to 48v at some point. Likely in stages.
Comments, criticism, safety suggestions in particular, etc all welcome.
(Edited to clarify a couple points.)
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