Wasted solar generation on the Spanish peninsula

This raises energy prices for everyone

On sunny hours the Spanish peninsula often produces more solar than the local grid can absorb. That energy goes unused while other sources (less green, more expensive ones) remain in the mix. Consumers end up paying for flexibility and system constraints twice over. This is measurable, costly, and largely avoidable with better infrastructure and market design.

What would help? Stronger grids, storage (that's batteries!) and price signals that reward using clean power when it is abundant. That reduces waste, eases bills, and puts scarce clean generation to work.

Put in perspective

Today's unused solar total is in the ballpark of the daily electricity of about 556 typical homes, using an illustrative 12 kWh per home per day for scale (not a census count - see methodology).

Methodology

Quarter-hourly unused solar (MWh) is derived from Red Eléctrica de España (REE) data, processed in a separate pipeline and stored in this project's database: each row is keyed by date with 15-minute buckets of unused energy. Multiple rows for the same day are summed bucket-wise before display.

The chart aggregates those quarter-hours into 24 hourly bars. Any slots beyond the first 96 are folded into the last hour of the day. Day totals are the sum of all quarter-hour values. “So far this year” uses the sum of MWh across rows from 1st January through the selected date. The average “per hour” figure is the mean of the 24 hourly bars (equivalently the day total divided by 24).

Euro amounts appear as a simple illustrative rate for energy, not a market settlement: but they make clear that unused MWh are not economically neutral.

Household analogy

The household comparison uses a configurable illustrative kWh/day figure to give an intuitive scale.

Credits

This site was directly inspired by Wasted Wind, a data project by Robin Hawkes about wasted wind energy in Great Britain. I am grateful for that work as a model for explaining curtailed renewables in a clear, public-facing way.

About

I built Wasted Sun as a individual that cares about this with the objective of putting unused solar into plain sight.

I care strongly about this topic, including through my role as Head of Technology at Octopus Energy Spain - but unless stated otherwise, the analysis and opinions here are mine alone and do not represent my employer.