Home automation and solar panels: how to optimise energy use

The Valencia region gets a lot of sunshine, and more and more homes have solar panels. Yet a large share of production is often exported to the grid while nobody’s home, and energy is bought back in the evening. Home automation fixes that mismatch by moving consumption into the hours of production.

Why using what you produce pays

Spain’s Royal Decree 244/2019 defines several self-consumption schemes. In the most common one for homes (with surplus and simplified compensation), exported energy is credited on the bill — but generally at a lower value than the energy you buy. The upshot: every solar kWh you use at home is worth more than one you export.

What home automation needs to manage solar energy

1. Production and consumption data: from the inverter (via Modbus or another interface) or from a meter in the consumer unit.
2. Controllable loads: equipment that can be switched or modulated.
3. Rules: which loads to activate at what surplus, in what order of priority.

Loads you can move into sunny hours

Load	How it uses solar	Notes
Electric water heater	Heat with surplus	Works as a “thermal battery”
Heat pump (hot water and heating)	Make hot water or condition the house in sunny hours	Depends on the unit’s compatibility
Electric car	Solar charging at a power matched to surplus	Needs a controllable charger
Pool pump	Schedule centred on production hours	Easy and effective in summer
Air conditioning	Pre-cool or pre-heat with surplus	The building’s thermal mass acts as storage
Appliances	Delayed start at midday	If the appliance supports it

Priorities and safeguards

• Priority order: the biggest wins first (water heater, car), extras afterwards.
• Hysteresis: don’t switch loads on and off every time a cloud passes.
• Respect contracted power: avoid peaks when you’re also drawing from the grid.
• Comfort first: hot water and room temperature must be guaranteed even without sun.

Worked example: a home with PV, a heat pump and an electric car

• Data: inverter readings plus a whole-house meter in the consumer unit.
• 10:00–12:00: with surplus, the heat pump produces the day’s hot water.
• 12:00–16:00: the car charger matches its power to the available surplus.
• Summer: the pool pump runs in sunny hours; the air conditioning pre-cools the house before the afternoon.
• Cloudy days: water heater and car fall back to the cheapest night-time hours.
• Tracking: the app shows how much was self-consumed and exported each day.

Common mistakes

• Installing panels without planning how to use the output.
• Switching loads with every cloud because no delays are configured.
• Automating without measuring, so you can’t tell whether self-consumption improved.
• Not checking whether the inverter or charger supports integration.
• Prioritising low-value loads over the ones that save most.

Conclusion

The panels produce; home automation decides what that energy is used for. With inverter or meter data and a few simple rules, the water heater, heat pump, car, pool and climate system work with the sun — you export less and buy less. If you’re planning a new home, build this in from the design stage (see what architects and builders should plan).

Domolife integrates energy management into home automation projects. Tell us about your installation.