I also found my panels locally off Craigslist. You can easily check the voltage of your panels, but a more informative number will be the amperage they put out. I would not hold my breath expecting to get 60% output on rainy day. That is most likely marketing department BS. Stick with 10% until you have a
measured value. This is easy to do. Get a clamp meter like this one. Besides being able to measure both AC and DC current, it is also designed to measure "inrush" current, the monentary spike in current draw in the first few milliseconds of startup.
Specifications Range UT216C. AC current (A) 600A ±(2.5%+5). DC current (A) 600A ±(2.5%+5). Jaw opening ã 30mm. Analog bar graph. VFC, low pass filter. Why Choose us. Display count ã 6000.
www.ebay.com
Compared to me, I'd say that 20kWh/day is very high, for routine living. With lights, TV, and the refrigerator running 24/7, I use around 3-4kWh per day. I only consume 20kWh on days I'm pumping water. Your first job should be focusing on cutting your consumption rather that building your system.
I've always gone with lead-acid. I consider off-gassing to be a non-issue. You really don't what your power system in the living room anyway. Have it positioned in the garage, or some small ultility room, something like an unused laundry room. Running a central air-con off-grid is going to be very, very expensive. I run just one 8000BTU wall unit.
If you want to buy a quality off-grid inverter, look at names like Magnum, Schneider, and Outback. Make sure you get an inverter with ample surge capacity for electric motors. Most AiO high-frequency inverters only surge to 200% current for 16mS or so. That most likely will NOT start a big electric motor with a high inrush value.