How does UK solar output change through the year?

UK solar output varies through the year, so model monthly generation before deciding how much your business can use. A Cambridge PVGIS run produces 36.24 kWh per installed kWp in December under stated layout and loss assumptions [S2]. Compare the whole seasonal profile with your operating hours; batteries need surplus to charge. Checked October 2026.

Last checked 18 October 2026

How does UK solar production change from winter to summer?

Solar output follows the available light, with location, panel direction and weather shaping the result. PVGIS, the European Commission’s Photovoltaic Geographical Information System, models radiation and system performance. Its methods account for direct and diffuse light, temperature and other losses [S1].

Start with solar panels for business for the wider project. For your business, follow the energy through this sequence:

The monthly profile below is a Cambridge example. It is not a national average or a forecast of next year’s weather. Use solar yield by UK region for the separate regional question.

How much electricity does the Cambridge model produce each month?

The PVGIS calculation uses Cambridge at latitude 52.205, longitude 0.119, crystalline-silicon panels, a fixed south-facing array at 35° tilt, free-standing mounting and an assumed 14% system-loss input. Terrain horizon is enabled. The returned radiation database is PVGIS-SARAH3, covering 2005–2023 [S2].

Free-standing is the model’s mounting setting for a ventilated array. Your actual roof construction and temperature behaviour need checking before reusing it. The loss input is an assumption, not a measured loss for every commercial roof.

A kilowatt (kW) measures power; a kilowatt-hour (kWh) measures energy. Kilowatt-peak (kWp) describes panel capacity under reference conditions. PVGIS accepts peak capacity and reports energy output [S3]. The final column scales the model to an assumed 50 kWp workshop roof.

Monthly figures come from PVGIS [S2]. Workshop figures equal each monthly value × 50, rounded to whole kWh. The annual row uses the returned annual total; separately rounded monthly rows can differ slightly when added.

This is an illustration, not a quote. Scaling assumes the same orientation and losses throughout, without extra site shading, export curtailment or equipment restrictions. A designer must model those separately where relevant.

Why should you avoid dividing annual output equally across the year?

In this run, July’s 124.29 ÷ December’s 36.24 gives about 3.43 times as much monthly energy [S2]. That ratio belongs to this location and layout. It is not a universal winter multiplier.

The workshop’s annual 52,038 ÷ 12 would suggest 4,337 kWh every month, rounded. December’s scaled result is only 1,812 kWh. Equal allocation would hide a substantial seasonal shortfall even before considering when equipment operates.

PVGIS reports multi-year average monthly production. It also describes variability between years [S3]. A monthly mean does not promise a particular day’s generation. Keep both seasonal patterns and weather uncertainty in the proposal; do not schedule essential operations around a monthly average alone.

Request the full calculation export and input record, so changes in roof angle or loss assumptions remain visible.

Can monthly generation tell you how much electricity the site uses directly?

No. Generation and demand must coincide. Energy Saving Trust explains that using solar electricity during generation hours increases direct use, while storage can move some surplus into later hours [S4]. Its household cost examples are not commercial cost evidence and are not used here.

For an assumed workshop, suppose July demand totals 7,000 kWh while the scaled model produces 6,215 kWh. Subtracting those totals gives 785 kWh, but that is not a valid import forecast. The workshop could export at lunchtime and import during an evening shift within the same month.

Ask for interval generation and consumption matched on the same clock. Mark weekend shutdowns, summer holidays, refrigeration and any vehicles charging during daylight. A council office and a seasonal attraction can use the same annual energy yet have very different overlap.

Read self-consumption versus export for the accounting boundaries. Keep direct use, stored output and export as separate destinations.

Can a battery move summer solar into winter?

A battery holds energy for later use, but capacity and available charging energy constrain what it can move. Energy Saving Trust distinguishes stored energy from charging and discharging rates [S5]. A routine daily storage calculation should not be presented as seasonal storage.

For a separate illustration, assume the workshop has 100 kWh of solar surplus on a particular day and 90% whole-system storage efficiency. Delivered energy would be 100 × 0.90 = 90 kWh, provided storage space, charging power and later demand permit it. Both inputs are assumptions.

If a winter day has no surplus, that solar-charging opportunity disappears. Grid charging would need a different operating and cost calculation. A larger cabinet does not create missing solar generation. Use commercial battery sizing to test power, energy and charging windows.

What this means for your site

Assess the roof across your working calendar. Ask the designer to show a winter working day, a sunny closure day and the period when vehicle charging is busiest. Request separate totals for direct solar use, battery losses, export and remaining imports.

Use commercial solar cost data and its East of England page alongside this Cambridge example. Cost per installed kW and energy per installed kWp answer different questions. DESNZ publishes cost statistics on declared net capacity and total installed capacity bases; identify which basis a cost comparison uses [S6].

For a financial assessment, combine the accepted generation model with actual operating data and contract prices. Do not apply an assumed avoided unit price to every generated unit when some will be exported or lost.

What should you do next?

Save your monthly generation model and request a time-matched consumption assessment. Continue through the cut energy costs hub and site check, then get matched with an installer that covers your area.

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