Hey everyone! I'm working on setting up a small battery backup system for home use, mainly to handle power outages. My target load includes two refrigerators, a wood stove, and some LED lights, so I'm estimating an average draw of about 600Wh. I found some JA Solar 405W panels for about $140 each and decided to build my system around two of them. Here's a layout I put together:
| Function | Model | Voltage | Watts |
|---------------|------------------|----------------|----------|
| Panels | JA Solar 405W | 31.21-37.23 | 810 |
| Charger | Bluesolar 100/30 | <100 max | 880 max |
| Battery | Litime 24V 25Ah | ....24? | N/A |
| Inverter | Victron 24/1200 | 18.4-34.0 | 850W |
I think I need some connectors and a fuse between the panels and charge controller, but I'm starting to worry that my system might be unbalanced. Any thoughts or feedback would be really appreciated!
3 Answers
It looks like you might be in for a surprise! You're quoting an average draw of 600W, which totals about 14.4kWh per day. Your setup with two panels may only produce around 2-3kWh daily, and with your current battery, you could run out of power after about an hour if the outage hits at night. I'd suggest looking into a much larger battery, possibly around 300Ah, to really get through those long outages. Keep in mind, you might also want to add a couple more panels to boost your output!
Absolutely right! The first step is to measure your actual power consumption. Get a Kill-A-Watt meter to track the daily usage of your fridges. This way, you can accurately size your battery based on how long your local power often goes out. Also, I’d advise sticking with a 24V system since they tend to be more efficient than 12V and more cost-effective than using a 48V setup. Those panel prices are decent too; why not invest in a couple more to have a backup?
You will definitely need more solar capacity! I recommend aiming for around 2-3kW of panels and a 300Ah battery at 12V to meet your needs comfortably. The Victron equipment is solid, and if you're in Europe, you might find similar prices for panels and batteries as I did — about 80 Euros for each panel and around 300 Euros for a good battery. Better be prepared for cloudy days!