Solar panels on a stadium roof are mostly a poster

The building draws its serious power on twenty nights a year, which is precisely when the sun is not helping.

Count the nights the floodlights are actually on. Twenty-five, maybe thirty for a busy ground with two tenants and a concert season. That is when a stadium's electricity demand spikes to something enormous, and it is, almost by definition, dark.

Which is the whole problem with the roof full of panels in the press release. The generation profile and the demand profile barely overlap. On a July afternoon the array is producing beautifully into an empty building. On a Tuesday in November at eight in the evening, with the lights up, the pitch heating running, the kitchens going and forty thousand phones hunting for signal, it produces nothing at all.

So what does the array actually do? It sells power back to the grid during the day and offsets the annual total on paper. That is not fraudulent and it is not useless. Renewable generation is renewable generation regardless of who consumes it. But it is a different claim from the one usually made, which is that the stadium is powered by the sun, and the gap between those claims is where I get irritated.

The honest version of stadium energy work is duller and more effective, and it starts with the base load. A large ground consumes power continuously: offices, a club shop, a museum, a hotel in some cases, catering cold storage, security systems, and increasingly a data centre's worth of network equipment. Across a year, that steady draw can outweigh the match night spikes, and it happens during daylight, and it responds to exactly the interventions nobody photographs. Better controls. Efficient chillers. Turning things off.

Then storage, which is the piece that would actually change the picture. Batteries charged from the array through the week and discharged into the floodlight peak would connect the two profiles, and would also earn money from grid services on the many days when nothing is happening at the ground. That is a real project with a real payback, and it is invisible.

I would rather a club spent on the plant room than the roof. But nobody puts a picture of a heat pump on the front of the annual report.

The array is not a lie. It is just an answer to a question the building was not asking.