You can buy a lithium battery in many markets and online. You can also get one from your solar installer. Which is better?
What can go wrong with a market battery
- Fake capacity. The label says 10kWh. The battery holds much less.
- Weak cells. Grade B or used cells inside a new box. Read Grade A vs Grade B cells.
- Weak BMS. Poor protection inside.
- No local warranty. The seller disappears or says "no refund".
- Wrong match. It does not work well with your inverter.
Side by side
| Market battery | Installer-supplied battery | |
|---|---|---|
| Matched to inverter | You must check | Yes |
| Set up correctly | Depends on technician | Yes |
| Cell grade known | Often not | Should be stated |
| Warranty claims | Hard | One company to call |
| Shelf price | Sometimes lower | Sometimes higher |
Settings matter
Lithium needs the right charge voltage, cut-off and current. Wrong settings shorten its life. A good installer sets these and tests them.
If you buy it yourself
- Get the datasheet.
- Check it is LiFePO4.
- Ask for kWh, not just Ah.
- Ask for a written warranty with the seller's address.
- Check it works with your inverter model.
