Off-Grid
Commercial / Business
Off-grid, or stand-alone, is a solar PV (PLTS) scheme that is not connected to the PLN grid at all. The system relies on a battery as an energy buffer to store daytime production and release it to loads at night or during cloudy weather. It is usually equipped with a separate charge controller and a dedicated off-grid inverter.
Synonyms: Stand-Alone, Stand Alone
Off-grid is the dominant scheme for areas not yet reached by the PLN grid — remote communities in eastern Indonesia, small islands, or mining and plantation sites far from electricity distribution points. Because there is no grid as backup, the system must be designed with a high safety margin: panel capacity above daily demand, a battery with 1-3 days of autonomy, and usually a diesel genset as a backup of last resort.
The biggest consequence is cost. The battery component often contributes 40-60% of total off-grid system cost [docs/data-kalkulator.md], with a 5-10 kWh residential LFP battery in the Rp 5.5-7.5 million per installed kWh range. This cost does not yet include battery replacement in year 10, assuming a 6,000-cycle life.
In addition, an off-grid inverter must function as a voltage source (forming its own voltage and frequency) and handle inductive load surges such as a water pump motor or an AC compressor — its surge rating specifications are stricter than an on-grid inverter's.
Indonesian PLTS Application Example
A small-island community with a daily load of 30 kWh needs an off-grid system of ~10 kWp of panels, ~20 kWh of LFP battery (1 day of autonomy, DOD 0.90), a 5 kVA off-grid inverter, and a 5-10 kVA backup genset. The typical total investment is Rp 18-22 million per kWp-equivalent — twice that of an on-grid system because of the dominance of the battery component and the oversizing margin.
Sources & References
- SolarPlanner.id Calculator Data, SECTION 8 (off-grid systems) and SECTION 1.3 (LFP battery price Q1 2025) — SolarPlanner.id (2025)
- IEC 62124, Photovoltaic (PV) stand-alone systems — Design qualification — IEC (latest)
See Also
On-Grid
On-grid, or grid-tied, is a solar PV (PLTS) scheme that is connected in parallel with the PLN grid and uses no battery. The inverter synchronizes its output to PLN's voltage and frequency; when the panels produce more than the load, the surplus flows to the grid, and when production is insufficient, the load draws from the grid.
Hybrid
Hybrid is a solar PV (PLTS) scheme that combines a PLN grid connection with an energy-storage battery. The hybrid inverter manages three flows at once: panel to load, panel to battery, and grid to battery (or battery to grid). This scheme provides electricity availability during PLN outages while optimizing self-consumption.
BOS
(Balance of System)BOS, or Balance of System, is every component of a solar PV (PLTS) system other than the solar panels themselves: the inverter, mounting structure, DC and AC cabling, electrical protection, combiner box, export-import kWh meter, and installation labour. In an Indonesian residential on-grid system, BOS typically accounts for 25-40% of the total system cost.