3 ms·

I could do this today. With my current time-of-use electric rate, I pay an average of $0.25/kWh more for peak power than I do for off-peak [the differential is

I could do this today. With my current time-of-use electric rate, I pay an average of $0.25/kWh more for peak power than I do for off-peak [the differential is larger in the summer, smaller in the winter]. If I shift 8kWh per day, then I would generate positive ROI in less than five years. Your edit is spot-on. Utilities typically use natural gas "peaker" plants to meet mid-day spikes in demand, while nuclear plants are better suited to running at a steady state.

mrfusion 12y ago
And you'd get a free backup power system too. That's worth something.
bryondowd 12y ago
Is 8kWh/day realistic? I'm curious, honestly wouldn't know. Seems like that would be charging and discharging 80% of the 10kWh battery's capacity every day. Would that affect lifespan? Also, it would seem to render the device less useful as a battery backup system during most of the day, since it would be mostly depleted.
- URSpider94 12y ago
  My home uses about 1000 kWh per month, so shifting 8kWh per day of my in-house demand is feasible. However, there's really no correlation with my usage, since I can just push and pull that power from the grid, as if I had a solar or wind generator. Lithium batteries are fairly tolerant of deep discharge, but yes, I would expect that the pack would be worn out after max 7-10 years if used like this. Yes, using the pack like this would make it much less useful for battery back-up, but where I live (SF Bay Area), I haven't had an outage that lasted longer than 2 hours since we moved into our house, and this would cover the basics (probably everything but A/C) for that time. You could always split the difference, for example using 4 kWh per day -- this would pay still give you 6kWh+ of backup power and let you get the battery at half off or better.

3 ms·

I could do this today. With my current time-of-use electric rate, I pay an average of $0.25/kWh more for peak power than I do for off-peak [the differential is

by URSpider94 12y ago

mrfusion 12y ago
And you'd get a free backup power system too. That's worth something.
bryondowd 12y ago
Is 8kWh/day realistic? I'm curious, honestly wouldn't know. Seems like that would be charging and discharging 80% of the 10kWh battery's capacity every day. Would that affect lifespan? Also, it would seem to render the device less useful as a battery backup system during most of the day, since it would be mostly depleted.
- URSpider94 12y ago
  My home uses about 1000 kWh per month, so shifting 8kWh per day of my in-house demand is feasible. However, there's really no correlation with my usage, since I can just push and pull that power from the grid, as if I had a solar or wind generator. Lithium batteries are fairly tolerant of deep discharge, but yes, I would expect that the pack would be worn out after max 7-10 years if used like this. Yes, using the pack like this would make it much less useful for battery back-up, but where I live (SF Bay Area), I haven't had an outage that lasted longer than 2 hours since we moved into our house, and this would cover the basics (probably everything but A/C) for that time. You could always split the difference, for example using 4 kWh per day -- this would pay still give you 6kWh+ of backup power and let you get the battery at half off or better.