Solar and heat pumps: €27k cost, €3k tax deduction

Solar panels, heat pumps, and EVs: €27,000 invested for a €3,000 tax break

Two years after applying for grants, the owner of a detached house in Madrid still doesn't know if they will receive any subsidy for their solar panels and heat pump. What they do know is what they paid: €12,000 for 9 kW of photovoltaics and €15,000 for the heat pump. In total, a €27,000 investment and an income tax (IRPF) deduction that, with a joint return, comes to just €3,000. Not even half the tax savings often advertised. Their conclusion, after years of tracking, is simple yet uncomfortable: if you need a spreadsheet to make it free, don't install it.

Why the IRPF deduction is never the promised €6,000

The limit for energy efficiency improvements is €3,000 on a joint return, a detail that dismantles sales arithmetic. The real case described is telling: a couple who would pay €1,200 and €500 separately without installation—or get €1,000 back jointly—sees their refund rise to €1,800 and €2,500 separately, or €4,000 jointly with the bonus. The actual benefit compared to the no-work scenario is €3,300, not €6,000. They also note a condition: the €3,000 applies only if the energy certificate improves by 30%; below that, the figure drops to €1,000.

1,800 kWh for heating: the bill brochures hide

Heat pumps were sold as the end of energy costs. In this case, in central Madrid, with winter temperatures ranging from +10°C to -1°C, there are months where 1,800 kWh is used just for heating at a set point of 21°C. Photovoltaics don't cover the gap: in December, a month with 1,500 kWh consumption produced barely 400 kWh. The system works, they like it, and would reinstall it with ample funds, but the dream savings require living in a specific area, with a specific climate, and a well-insulated home.

Subsidies: an endless list of things that can go wrong

In their view, never count on public money in your numbers. From closing the bank account used for payment to paying invoices via a partner's profile on a joint account, including undeclared work surfacing during audits, unemployment leaving no tax liability to deduct, or management companies sending incorrect paperwork and taking a year to justify. Additionally, rehabilitation aid—up to €15,000 over three years—requires facade insulation or window replacement; simply installing panels and a heat pump does not qualify.

Batteries, surplus, and tariffs penalizing self-consumption

Here lies the paradox that confuses many. The same company offers a tariff of €0.10 per kWh (ex-tax) to homes without panels; those with panels, virtual batteries, and surplus pay €0.18 ex-tax and €0.25 inc-tax. Essentially, producing your own energy costs more per kilowatt-hour in this case. They add that virtual batteries pay surplus at €0.08 and charge it back at €0.14 plus taxes, while physical batteries operate between 20% and 80% capacity: of 10 kWh installed, only 6 are usable. Very expensive, in their opinion, for anyone planning to charge an EV at night.

Cases that work: fireplace, adobe, and zero subsidies

Not all is discouraging. Someone living 30 km south of Madrid in an adobe chalet covered the roof with 7 kWp for nearly €10,000, disconnected gas, and has paid nothing for electricity or heating for two years: a 60% deduction and a 50% property tax (IBI) reduction for a decade amortize the work, according to their testimony. Another calculation in eastern Spain estimates 6.7 years amortization with batteries and no grid injection. And an off-grid home with 12 panels and 18 kWh of batteries hasn't started its generator in a year. The key in all cases is sizing and prior insulation.

Electric car: 70 kWh just for parking

The third pillar of the combo hides its own trap. Sentinel mode—continuous vehicle surveillance—consumed 70 kWh in ten days with the car parked. Charging at night, when there is no sun, requires 20 or 30 kWh battery capacity, which rarely pays off in their view. The repeated recommendation is to install a hybrid inverter from the start to avoid buying another one later if batteries are added.

With these elements, the message is caution, not euphoria. The point where all calculations stall is, according to their experience, the same: the price retailers pay for surplus, which falls annually, versus rising tariffs. This differential determines the final result. And it will keep moving before anyone finishes amortizing anything.