A home battery setup cuts expensive evening power use
In California, PG&E peak power from 4 p.m. to 9 p.m. can cost almost three times as much as power around midnight. Selling extra daytime solar power to the grid for very little money, then buying costly power back in the evening, creates poor economics.
A Tesla Powerwall would have cost about $16,000 installed, pushing the payback period beyond 9 years. A DIY setup using a 51.2V 100Ah Vatrer Power and a 5kW Growatt cost about $6,000, including an electrician’s final interconnect work and a loads subpanel. During the day, solar power charges the LiFePO4 instead of being sent to the grid. From 4 p.m.
to 9 p.m., the home runs key loads from the battery, including the fridge, chest freezer, router, lights, and devices. Those essential loads average about 2kWh during that window, leaving extra battery capacity.
Key points
- PG&E power from 4 p.m. to 9 p.m. can cost almost three times the midnight rate.
- A Tesla Powerwall quote was around $16,000 installed, with payback beyond 9 years.
- The DIY battery and setup cost about $6,000 including electrician work.
- Solar charges the battery during the day, then the battery powers essential loads during peak hours.
- Low-power always-on gear such as a router and fits this kind of loads plan.