Surplus energy: how compensation works and where to look
Under simplified compensation, your supplier credits your bill for the energy you export: it never pays you cash, and the credit cannot exceed what you consumed that month. The rates published by suppliers currently range between 0.035 and 0.07 euros per kWh, so the fine print matters.
Captia Energy Team · Chartered, qualified engineers · Published · Reviewed
How does simplified surplus compensation work?
Most homes run under the simplified compensation scheme: the energy you export is discounted from your bill at the price your supplier assigns to surplus. It is not a sale, it is a credit, and that has two consequences worth knowing before getting excited.
- Compensation has a ceiling: at most it can bring the energy part of your bill to zero within each billing period. Whatever exceeds that ceiling is, as a general rule, lost.
- It only offsets the energy part: grid fees, fixed charges and taxes stay on the bill whatever your roof produces.
Why is the surplus price not the whole story?
It is tempting to pick a supplier on the surplus-price headline. But you pay for what you buy during many more hours than you export, so an expensive purchase price can easily eat a well-paid surplus. The sum that matters is the combination of both over your profile: how much you buy, when, and how much you export.
There are also offers that raise the surplus price in exchange for lock-in periods or fixed fees. None of that is bad in itself, but it belongs in the sum.
Where can you see the surplus prices, with their date?
We keep a comparison of surplus tariffs from the suppliers operating in the area, each with its official source and the date we checked it. It lives on our surplus tariffs page and we review it regularly, because these prices change without notice.
If we monitor your installation, this analysis is included: when a tariff stops paying off for your real export profile, we tell you.
When does selling to the market make sense?
Simplified compensation is not the only arrangement. You can also register as a producer and sell your surplus on the electricity market. The difference is not just the price: being a producer means extra registrations, invoicing the energy you sell, usually relying on a market representative or an aggregator, and taking on the tax obligations of that sale. It stops being a discount on your bill and becomes a miniature business.
For a home with a small installation, the paperwork and obligations usually eat up the price difference, which is why almost all residential systems in the comarca stay on simplified compensation. Selling to the market starts to make sense for a different profile: large roofs with small consumption, such as a farm warehouse that only draws power a few hours a day, where the surplus is so large that compensation falls short month after month.
One warning: switching arrangements is not a matter of pressing a button, it involves procedures with the distribution company and your supplier. Choosing well at the start, with your consumption curve in front of you, saves a good deal of work later. It is one of the decisions we settle in the study before legalising the system.
What if the surplus does not show up on my bill?
It is the most common fault after a new installation: the panels work, the meter records energy flowing out, and the bills keep arriving without the compensation line. There is almost always a loose link between two companies: the distribution company has to activate self-consumption on your access contract, and the supplier has to reflect it in your contract through the compensation annex. When one of them has not done its part, each points at the other and the neighbour is left in the middle.
The good news is that it is almost always fixed by complaining to the right link in the chain. Some suppliers settle the exported energy retroactively for the period of the mix-up and others do not, and that detail is also a criterion when choosing a company.
This is exactly the kind of loose end we consider part of the job. Getting the installation running is half the work; the other half is chasing whoever is responsible until the compensation appears on your bill, because until that day your surplus goes into the grid with nothing in return.
- Check the bill shows the surplus compensation line, with its kWh and price
- Get written confirmation from your supplier that your contract includes simplified compensation
- Check the installation appears in the regional self-consumption registry, which is also a requirement for the Valencian 40% deduction on a base of up to 8,800 euros
- Check the meter is bidirectional and is actually recording the export
Frequently asked questions
Can I actually get paid money for my surplus, or only a discount?
Under simplified compensation you only get a discount, and it is capped: your surplus reduces the cost of the energy you bought that month, but never pushes the bill below zero. Anything above the cap is lost. To be paid real money you must switch to selling on the market, with more obligations.
With an east-west roof, will I have less surplus?
Yes, and that is not bad news. An east-west roof produces 82% to 85% of what the same power would give facing south, but it spreads output across morning and afternoon, when the house actually uses energy. You get more direct self-consumption, the best paid use, and less cheap exported surplus.
If I switch supplier, do I lose the compensation?
No. The compensation arrangement is tied to your installation and your access contract, not to a particular company. When you switch, the new supplier must include the compensation annex, and it is worth asking for written confirmation. When comparing offers, look at the surplus price and the purchase price together.