reed cundiff wrote:
We have 1.4 kW of solar, 9.8 kW hours (720 amp-hours at 12 V)of lithium iron batteries (160#) and 4 kW PSW inverter. Since lithium iron phosphate batteries can be drained to less than 10% capacity, this is very close to equivalent of 1200 or amp-hours (12 V) of lead sulphide batteries. 1200 amp-hours (12 V) of PbS would weigh approximately 1000# which would cause us to be overweight - and where we would put that many batteries. The result is that we have been autonomous since June when system was fabricated by son Cary (who has a 1.5 megawatt solar project ongoing for power company). We have operated 1.5 kW a/c for 3.5 hours as combination of solar and batteries. Batteries have permitted full use of forced air heater for three days with solar panels covered (still got 12 amps through the 8" or so of snow). We still had over 60% of battery storage remaining. The cost of solar and lithium iron phosphate batteries is decreasing and we expect that they will become more popular with time.
Reed and Elaine Cundiff
Where did you get the LiFePO4, how much was it, what type of BMS did you use, and how long is the warranty.
I have been considering LiFePO4 when I can be comfortable with the reliability and warranty.
BTW, 1200 amp hours of AGM would be eight 6 volt Lifeline AGMs and would weigh 720 pounds. Still a lot heavier than the lithium!
