I'm planning to design a solar system to go off-grid, but I don't want to go overboard. I realize depth of discharge (DoD) is important, and my daily usage is around 30kWh. What's the best way to calculate my battery bank size? Should I aim for double or triple my daily usage?
2 Answers
Check your zip code for average sunny days per year. You'll want to decide how many days you want the system to last without power. Build your system based on that plan.
As a general rule, it's suggested to size your battery bank to support 3 days of usage. That's around 90kWh for your 30kWh daily need. You should also ensure that you can recharge the battery in a single good day of solar output. For lithium-ion phosphate batteries, plan to budget around $10k for that amount of storage.