August 2026 left a strange bill: Spain broke solar-generation records and, at the same time, the PVPC receipt for a typical household rose more than 20% on August 2025. Your panels are not broken. The 14:00 kWh and the 21:00 kWh no longer look alike. Midday drifted towards €0.045. Nine in the evening, towards €0.31. Surplus you export at 15:00 has traded at zero or negative.
If your supplier still sells you “what you don’t use, we compensate”, this month is the counter-example. They compensate at the midday price. You buy at the night price.
This August’s numbers, no adjectives
- The August wholesale pool sits around €120/MWh monthly, some 15% above July and well above August 2025.
- On PVPC, the cheapest hour of the month averaged 14:00 (~€0.045/kWh). The dearest, 21:00 (~€0.313/kWh). The month’s peak hit €0.39/kWh.
- On 1 August photovoltaics set a daily generation record (259 GWh). That same month a typical PVPC home paid about €61 in 21 days versus €50 in 2025: more than 22%.
- On 28 August the PVPC surplus price at 15:00 reached −€0.00076/kWh. Exporting that hour does not charge you — and does not pay you.
The paradox fits in one sentence: the more solar the system has at noon, the less your leftover kWh is worth; the hotter 21:00 is, the more expensive the kWh you buy.
What is happening in your house, not in the pool
- Self-consumption from 12:00 to 17:00. That is where panels really save you: you don’t buy. The grid price, cheap or dear, does not touch you.
- Surplus in those same hours. It goes to the grid at the market price (on PVPC, wholesale, without tolls). In August, often almost nothing.
- Consumption from 20:00 to 24:00. Air-con, hob, dishwasher, car. You pay peak. Your panels are gone.
That is why people have a “green” app at noon and an August bill higher than 2025. The app shows midday. The bill shows the night.
A typical day, in euros
Imagine 8 kWh of surplus at 15:00 and 8 kWh bought at 21:00, on this month’s PVPC:
- Surplus at ~€0.00/kWh → €0 compensation.
- Purchase at ~€0.31/kWh → €2.48 that night.
You have not “saved the surplus”. You gave the grid 8 kWh and paid €2.48 for another 8 kWh seven hours later. If those 8 kWh had sat in a battery, the night would have cost the charge cycle, not the tariff.
That does not mean everyone needs a battery. It means the 2022 sales line — “they pay you for surplus” — is a fairy tale in August 2026. We put supplier numbers on it in virtual battery vs physical battery.
What not to do with this headline
- Do not size the roof to export. Exporting at €0 does not pay for an extra panel.
- Do not panic if the plant is producing. If at noon you self-consume the air-con and the fridge, the system is doing its job. The hole is at night.
- Do not sign a “virtual battery” thinking it stores kWh. It stores cents at the midday price. That is not the same thing.
And one exception we do watch: if the bill rises and at noon the plant produces as if panels were missing, that is not the pool. It is a string, a fuse or a new shadow. We cover that in how we watch plants.
What does make sense in September
- Look at your curve, not the headline. If from 21:00 to 24:00 you buy 10 kWh every hot day, the debate is shifting load (air-con, tank, car) or storing. If there is almost no night use, August’s headline barely touches you.
- Midday air-con is the panels’ best ally. See air-conditioning and solar panels.
- A battery is not a catalogue extra. It pays when there is systematic midday surplus and expensive night consumption. In August 2026 that spread was brutal. In February, it is not.
The year is not decided by one month. But an August like this teaches the rule that will run the next ones: solar kWh is worth what you do with it at 21:00, not what they pay you at 15:00.
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Sources: August 2026 PVPC stats (cheapest hour 14:00, dearest 21:00); August wholesale pool ~€120/MWh; PVPC 21-day bill simulation (Europa Press / CNMC, 23/08/2026); PV daily record 1/08/2026 (AleaSoft / REE); PVPC surplus price 28/08/2026 at 15:00. Example figures rounded. This is not a forecast of your bill: that comes from your curve.