The power grid
Negative electricity prices at midday: why in 2026 a battery is worth more than selling your surplus
Spain keeps breaking records for hours with negative prices on the wholesale electricity market. It sounds like good news, and partly it is, but for anyone with solar panels it changes the maths: what you export to the grid at midday is worth almost nothing, and what you buy in the evening is still expensive. Here is how it affects a home on the Costa del Sol.
According to Montel's quarterly analysis reported by pv magazine, Spain clocked 397 hours of negative prices between January and March 2026, against just 48 in the same quarter of 2025. The whole of 2025 had 555. From April to June there were another 596 hours, the highest figure in Europe (Moncloa.com).
The reason is simple: at midday there is so much solar on the grid that there is energy to spare. On 21 February, between 12:00 and 12:45, the price fell to -€58.60/MWh with 15.6 GW of solar generating.
When the sun goes down, however, gas plants come in and the price rises. Electricity is no longer cheap or expensive depending on the day: it is cheap at midday and expensive in the evening.
What it means for your surplus
With surplus compensation, your supplier deducts the energy you export to the grid from your bill. On the regulated tariff it is valued at the market price for each hour; on the free market, at the price set in your contract.
When the market is at zero at midday, which is exactly when your panels produce the most, that surplus is worth very little. We break it down with numbers in our article on how much you really get paid for your surplus.
That is why, according to El Independiente, around 60% of new installations already include a battery. The industry calls it the second self-consumption revolution: moving from selling what is left over to storing it.
At midday the grid has energy to spare. In the evening it is expensive again.
On the Costa del Sol, the heavy use comes in the evening
In a home in Marbella or Estepona the big consumption does not happen at noon. It comes in the evening and at night: the air conditioning when you get home, the kitchen, the pool pump if it is not scheduled, charging the electric car.
Without a battery, the panels cover midday and you buy the rest from the grid at evening prices. With a battery, the energy you used to export almost for free is used at eight in the evening, when each kWh costs the most.
It does not always pay off. A battery is a significant investment and has to be sized to your real consumption. If the house is empty for much of the year or you mostly use power during the day, it may not add up. We cover this in our article on whether a solar battery is worth it.
How we work it out
Before proposing a battery we look at your bills or, better still, your hour-by-hour consumption curve, which you can download from your distribution company's website. That shows how much energy you use when there is no sun.
With that we know whether it suits you, what size and how long it takes to pay back. If you install it in 2026, you can also claim the new 10% IRPF deduction, which includes batteries.
Send us an electricity bill and we will prepare a free study for your home in Marbella, Estepona or anywhere on the Costa del Sol.
