Dehumidifier on solar panels: consumption and when it pays
Living in a humid area, the dehumidifier runs many hours. 200-400 W steady can be a surprise bill. How to schedule it for solar hours.
A dehumidifier looks small but, running 12-16 h/day in a coastal area, adds $100-200 to the annual bill. With solar, only the midday operation is free.
Consumption by capacity
12 L/day model: 200 W. 20 L/day: 320 W. 30 L/day: 480 W. Running 12 h/day: 12 L → 880 kWh/year, 20 L → 1400 kWh/year, 30 L → 2100 kWh/year.
When it auto-starts
Humidistat detects relative humidity. Triggers above set point (50-60% typical). Coastal areas and humid US states exceed 60% most of the year. Dry interior: almost never.
Solar strategy
Schedule operation 9 AM to 6 PM (sun hours). Humidistat lowered to 55% during this window, raised to 65% at night (won't kick in). Save 50% consumption, all from free solar.
How many panels
1000 kWh/year (typical use): one 410 W panel in good sun covers. Very humid area at 2000 kWh/year: 2-3 panels. Definitely pays back: a dehumidifier is more cost-effective than AC.
Heat pump: the 'free' dehumidifier
If you already have inverter AC or heat pump, both dehumidify as a side effect. Running AC in 'dry' mode at midday eliminates the need for a dedicated dehumidifier.
Combine with solar heat pump.
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