Path-Q Solar
How much extra solar capacity might an electric heat pump require?
Answer
The extra capacity is determined by the heat pump's annual electricity consumption divided by the site's expected annual production per unit of solar capacity, with seasonal and usage assumptions included. There is no reliable single-size answer without the heat pump, climate, building, and existing load data.
Key points
- Heating and cooling demand, equipment efficiency, and climate drive the added energy use.
- A heat pump's winter consumption may not align with winter solar production.
- Backup resistance heat can materially increase peak and annual demand.
- Model annual energy, monthly production, peak electrical demand, and any battery or grid requirements separately.
What it depends on
- Heat-pump efficiency and capacity
- Climate and heating/cooling hours
- Building envelope and thermostat settings
- Backup heat operation
- Existing household consumption and solar production
Risks and trade-offs
- Using a generic heat-pump estimate can understate winter demand.
- Oversizing the array for rare extreme conditions may reduce economic efficiency.
- The required electrical service or inverter capacity may change even if annual energy use does not.
Information you may need
- Proposed equipment specifications
- Recent heating and cooling energy use
- Building size, insulation, and climate information
- Backup-heat assumptions
- Existing or proposed solar production estimate
Your next step
What to do next
Have an installer or energy analyst model the proposed heat pump's annual and peak demand and compare solar designs with and without that load.
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