Comment Re:Selling solar to PG&E (Score 1) 332
For my UK supplier, there's around £0.20 per kWh difference in the two rates, so every 5kWh of battery capacity saves me about a £1 per day. A decent 5kWh modular battery pack can be had for around £1,500 so, allowing for some inefficiencies, RoI is around 5 years, and the battery packs are often guaranteed to last for at least 10 years, with some allowance for capacity reduction - typically to less than 80% with that kind of daily cycle pattern. The practical capacity limit on stacking the modular batteries is how much charge you can get into each stack within the cheap rate window, but you can run and charge more than one array of batteries in parallel if you know what you're doing. We currenly have a little over 20kWh of batteries installed and even with a PHEV our bill is almost entirely based on the cheaper overnight rate, rather than the daytime peak rate.