Generator Role in Solar Systems
In off-grid and hybrid systems, diesel generators serve as backup during extended cloudy periods or peak demand. Proper sizing and integration with solar + battery can reduce generator runtime by 60-80%.
Sizing Methodology
Generator size (kVA) = Peak Load (kW) ÷ Power Factor (typically 0.8). For solar hybrid: Size generator to charge batteries at C/5 rate while serving base load. Oversizing causes wet-stacking; undersizing causes overload trips.
Fuel Comparison
- Diesel: Most common. 10-15 kWh per gallon. Long storage life with treatment.
- Natural Gas: Unlimited supply from pipeline. Lower energy density. Cleaner burning.
- LPG/Propane: Indefinite storage life. Lower maintenance. Popular for standby generators.
Hybrid Control Strategy
Tier 1: Solar + Battery serve load. Tier 2: When battery SOC < 30%, start generator to charge batteries and serve load simultaneously. Tier 3: When battery SOC > 85%, stop generator. This "bulk charging" strategy maximizes generator efficiency by running it at 70-80% rated load.