15kWh Battery for Solar System

15kWh Battery: Capacity and Chemistry

A 15kWh battery stores enough energy to carry a typical home or small commercial unit through the evening and overnight. Chemistry matters more than the headline number: LiFePO4 delivers more than 6,000 cycles against roughly 1,500 for lead-acid, which is why a 15kWh battery built on LiFePO4 outlasts three lead-acid banks at a lower lifetime cost.

The U.S. Department of Energy energy storage programme documents why lithium iron phosphate now dominates stationary storage.

Size a 15kWh battery from the overnight load, not the daily total. List what must stay running between dusk and dawn, sum the watts, multiply by the hours, and compare that figure with the usable capacity after depth-of-discharge limits.

A refrigeration unit, lighting, internet and a fan typically draw 300 to 600 watts continuously. A 15kWh battery covers that for a full night with margin, and adding an air conditioner to the backup circuit is the point at which most buyers step up a size.

Mars Solar manufactures a 15kWh battery in-house with matched BMS, thermal management and communication to our hybrid inverters. Buying direct removes distributor margin and avoids the compatibility risk of mixing a third-party battery with a different vendor's inverter.

Each 15kWh battery carries a 10-year warranty. See larger bank options on our rack mounted energy storage battery page and complete systems such as the 80kW BESS.

Every 15kWh battery is cycled before it ships: one full charge to 100% state of charge, a rest period, then a controlled discharge to the low-voltage cut-off while cell temperature, cell delta and internal resistance are logged. That report ships with the unit, and it becomes the baseline you compare against at year five.

A 15kWh battery is most often paired with a 5kW or 10kW hybrid inverter, so the BMS ships pre-configured for those charge currents and talks over RS485 and CAN. If your inverter speaks a different protocol, we map it on the bench before dispatch and confirm handshaking with a live test.

Usable life depends on depth of discharge. Push a 15kWh battery to 90% DoD every night and you trade calendar life for capacity; hold it near 80% and the LiFePO4 cells typically pass 6,000 cycles before they reach 80% of original capacity. We size to the overnight load so you land in the second case, and the warranty covers ten years on cells and BMS with capacity retention guaranteed at 70% or better.

Installation is straightforward. The rack bolts to the floor, DC cables terminate on a labelled busbar, and the 15kWh battery handshakes with the inverter on first power-up. Commissioning takes under an hour for a trained installer, and because the pack is modular a single failed module can be swapped without taking the whole bank offline.

If you are still deciding between capacities, the 15kWh battery sits between the smaller residential packs and the containerised units: enough for a full night of essential load in a mid-size home or a small commercial unit, without the footprint or the permitting work of a container.