Solar Power and Accumulators

Solar panels

A solar panel is a 3×3 building that generates electricity from daylight. Output scales linearly with sunlight — up to a peak of 60 kW during full daylight, dropping to zero at night. Because days on Nauvis are considerably longer than nights, each solar panel averages 42 kW of power output over a full day-night cycle.

Solar panels generate zero pollution and require no fuel. Their drawbacks are high material and space costs compared to steam power, and no output at night unless paired with accumulators.

Solar and steam power work well together. Steam engines throttle down automatically when solar is supplying enough power, conserving fuel during the day.

Accumulators

An accumulator is a 2×2 electrical battery. It charges when supply exceeds demand and discharges when demand exceeds supply. Charge and discharge rate is capped at 300 kW. Capacity is 5,000 kJ. Accumulators are 100% efficient with no capacity loss over time.

Accumulators are most commonly paired with solar panels to maintain power through the night. The ratio needed to fully cover nighttime demand is 21 accumulators for every 25 solar panels (approximately 4:5).

In terms of grid priority, accumulators charge last — only after all other power demand is met — and discharge last, only after all generators are running at full output. This means a solar-accumulator system smoothly hands off between day and night with no manual intervention.

For more advanced setups, a circuit network can trigger steam turbines to start only after accumulators have been partially or fully drained, letting you run a hybrid solar-steam base with minimal coal use.

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See also:

• Steam Power and Electric Grids
• Electric Poles and Grids
• Nuclear Power

External links:

• Official Factorio Wiki: Solar panel