4 ms·

Li-ion batteries are mostly useful to shift the load by a couple of hours, that is to be able to sell cheap to produce solar power in the evening when the deman

• rstuart4133 8y ago
  I didn't realise just how useful that "shift load by a couple of hours" was until I got a battery installed at home. Before my PV + battery system was installed, I paid about $0.21 for each kW.hr consumed. After it was installed, the same power company offered to pay $0.11 for feed in. So I looked around. There is another company that would charge $0.19 for power consumed, and $0.20 for feed-in, with a catch. The catch is encoded in a complex formula, but it boils down to "we hit you hard if consume power during the 4 hour peak hour period at _any_ time during the 90 day billing period". My battery isn't big enough to supply an entire day or act as a back up during an extended power outage - but it can easily shift the 4 hours power usage this plan needs. Just doing that makes a big difference since we produce twice what we use. Who would have thought just having a 4 hour battery could drop your power bill by 1/3? Even more impressively, the battery says on the box it is good for 6,000 cycles. But they are full cycles, and if I just use it for 4 hours I'll never use a full cycle. It could last over 20 years if I only draw on it 4 hours a day.