Choose the system architecture
A stand-alone system needs generation, a charge controller, batteries, an inverter, safety disconnects and meters. How these connect (DC coupled or AC coupled) affects efficiency, expansion and cost.
How
- DC coupled: panels feed an MPPT charge controller that charges the battery directly, and an inverter makes AC from the battery. This is the common choice for new off-grid builds and suits loads that run mostly at night, because energy is stored first.
- AC coupled: panels feed a solar inverter that produces AC, and a battery inverter/charger stores the surplus. Off grid, the battery inverter controls the solar inverter by shifting its AC frequency: as the battery fills, it raises the frequency and the solar inverter throttles back. One maker (Victron) limits AC coupled PV to no more than the inverter/charger VA rating (its Factor 1.0 rule), sets minimum battery sizes per kWp, and requires DC coupling for off-grid systems on its own products. Only use combinations the makers list as compatible.
- Hybrid designs can mix both, and can add wind or hydro through their own dedicated controllers.
- List the balance of system parts you will need: charge controller(s), battery bank, inverter/charger, disconnects, fuses, meters and monitoring.
- Decide early whether any loads will run on DC directly (lights, small pumps) or everything on AC.
Sources
- Grid-Connected or Stand-Alone Renewable Energy Systems. US Department of Energy, Energy Saver, accessed 2026-11
- Balance-of-System Equipment Required for Renewable Energy Systems. US Department of Energy, Energy Saver, accessed 2026-11
- A Primer on Small Wind Systems. Bergey Windpower, accessed 2026-11
- AC coupling and the Factor 1.0 rule (Victron Energy documentation). Victron Energy, accessed 2026-11