Lithium Battery for Solar: Sizing Your Off-Grid Storage
Lithium Battery for Solar: Sizing Storage That Actually Pays
A lithium battery for solar lets you use PV when the sun is down and ride through outages. LFP is preferred for its deep-cycle durability. Pair it correctly with a home energy storage system for best results.
Sizing in Three Steps
- Sum daily kWh consumption of loads you want to cover.
- Multiply by backup hours (e.g., 1 day = x1, 2 days = x2).
- Divide by usable depth (0.8 for LFP) to get nominal pack size.
Example
| Load | kWh/day |
|---|---|
| Lighting + fridge | 5 |
| Backup 1 day | 5 |
| Nominal @0.8 DoD | 6.25 kWh |
Tips
- Size for critical loads, not the whole house, to cut cost.
- Use a hybrid inverter with MPPT for clean solar coupling.
- Choose a lithium battery manufacturer with matched BMS and inverter comms.
Frequently Asked Questions
How deep can I discharge?
LFP tolerates 80-90% depth of discharge daily; lead-acid should stay above 50%.
Do I need an inverter?
Yes, a hybrid or off-grid inverter converts DC battery power to AC and manages solar input.
Written by Karl at China Battery Technology. Request a quote.
