Annual yield per season
For a typical Belgian installation, the distribution looks roughly like this:
- Spring (March to May): About 30 to 35 percent of the annual income. April and May are often top months: lots of light and cool air.
- Summer (June to August): About 35 to 40 percent. The absolute peak, although heat slows down the efficiency slightly.
- Autumn (September to November): About 15 to 20 percent, with a rapid relapse from October.
- Winter (December to February): About 5 to 10 percent. December is the soil: often less than a twenty-fifth of what June delivers.
That distortion isn't a design flaw, it's physics. It does mean that you never dimension your installation on the winter: who calculates how many solar panels he needs, counting on annuality and accepting that December remains lean.
Cold is good, snow is not so bad, sunset is the culprit
A persistent misconception is that solar panels do not cope well with cold weather. The opposite is true. Solar cells become more efficient as they get colder; a clear, frosty day delivers more per hour of sunlight than a sweltering July day. The winter challenge is not temperature but limited light: short days, a low sun angle and thick cloud cover.
This low solar position has a mean side effect: objects cast longer shadows. A chimney or tree that doesn't stand in the way of anything in July can cover half a string in January. How heavy that weighs and what you do about it, read in shade on solar panels.
What about snow? A snowy panel delivers nothing, but in Belgium snow is rarely long. Panels are tilted, become dark and warm as soon as light comes through, and the snow usually slides off by itself. Climbing up the roof to wipe yourself is never worth the risk.
Rule of thumb: never compare your winter earnings with last month, but with the same month last year. If you're in the same order of magnitude, your plant is healthy.
When is a low winter return suspicious?
Unfortunately, the winter is also the season in which defects hide most easily: everything brings little, so nobody notices the difference. Note these signals:
- Your earnings are significantly lower than the same month last year., in comparable weather. That's more of a point. converter problem or a thong that went out in the season.
- The inverter displays error codes or slow start on: cold, damp mornings expose weak electronics and bad connectors mercilessly.
- One string remains structurally behind the other: typically a connector or wiring problem, not a winter problem.
In March or April, when the proceeds are due to explode, your plant is left behind, don't wait: every lost spring is the most expensive season to lie still. More landmarks can be found in Why you're losing revenue.
Smart handling of the winter valley
Wattra places new solar panels and also handles service questions for existing installations. In the event of a malfunction, we first discuss research and technical possibilities for repair or replacement. For a new installation we look at your roof, consumption and connection. Support for an existing device, documentation, inspection and registration are agreed by contract; the availability of parts and support for the brand is first checked.
Frequently asked questions about solar panels in winter
Cannot find your question? Call or email us for an answer from an installer rather than a salesperson.
How much do solar panels pay in winter?
The three winter months together deliver roughly 5 to 10 percent of the annual income for a typical Belgian installation. December is the bottom. That is normal: the days are short, the sun is low and it is often cloudy.
Do solar panels work in freezing weather?
Yes, even better per hour sunlight: solar cells are more efficient as they are colder. A clear freezing day can perform surprisingly well. The winter valley is not due to the cold but to the lack of light.
Should I wipe snow off my solar panels?
No. In Belgium snow is rarely on panels for long periods of time: they are tilted and warm up as soon as light comes through, so the snow slides off itself. Climbing up the roof itself is dangerous and the missed yield of a few dark days is little.
My yield is much lower this winter than last winter. What now?
Compare first with the same month last year in comparable weather. If the difference remains large, think of a defect: a bumping inverter, a failed string or bad connectors. We measure the installation and give an honest verdict.
Does a home battery run in winter?
Less than in summer, because there is less surplus to store. But on clear winter days, the battery collects the excess for the evening, and it helps you press your quarter-hour peak demand all year round for the capacity tariff. We're counting it on your own quarter dates.
Is winter a good time for maintenance or repair?
Yes, even the best moment: every day stops costs the least in winter. Anyone who has his inverter or cabling repaired in January will go into the spring at full force, exactly when the yield should peak.
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What applies to your situation?
Equipment selection, price, scheduling and any conditions will be confirmed for your project. This information does not replace an assessment of your installation or an individual quote.
Also have new solar panels installed
Wattra also places new solar panels for homes, companies and associations of co-owners in Flanders. View the installation page for the preparation and your quote request; a service question about existing devices remains a separate assignment.
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