How Much Do Solar Panels Produce in Winter? Antalya Data

Solar panels in winter still produce in Antalya, but output falls markedly compared with the summer months. According to the European Commission's PVGIS tool, the specific yield in central Antalya is 99 kWh/kWp in December and 168 kWh/kWp in July. So December output is about 59 percent of July's (calculation). In this article we cover winter output with data, the effect of cloudy weather, winter care and how to set expectations correctly.

Winter and summer output in Antalya: PVGIS figures

With the assumptions of PVGIS 5.3, 14 percent system loss, optimum tilt and south orientation, the monthly specific yield for central Antalya is as follows (kWh/kWp): January 99, February 108, March 142, April 150, May 157, June 159, July 168, August 167, September 155, October 137, November 114, December 99. The annual total is about 1,656 kWh/kWp.

Two important conclusions follow from these figures. First, the total for December, January and February is about 306 kWh/kWp, which is about 18 percent of the annual total. Second, the total for June, July and August is about 494 kWh/kWp and makes up about 30 percent of annual production (calculation). In other words, a sunny summer month produces about 1.7 times as much as a winter month.

The daily averages are calculations made by dividing the monthly value by the number of days in the month. Actual output on a given day can fall both below and above this average depending on cloud cover; PVGIS is a long-term average, not a guarantee for a single month.

Why does output fall in winter?

There are three basic factors: sunshine duration, the angle of the sun and cloud. According to Turkish State Meteorological Service (MGM) data for 1930-2025, average daily sunshine in Antalya is 4.8 hours in December, 4.9 hours in January and 11.7 hours in July. According to GEPA (the Ministry of Energy and Natural Resources solar atlas) data, global radiation is about 1.92 kWh/m² per day in December and about 6.65 kWh/m² in July. This difference comes both from the shortness of the day and from sunlight travelling a longer path through the atmosphere.

The low position of the sun in winter also changes the effect of panel tilt. A flatter tilt is better for summer and a steeper one for winter; for year-round output a middle value, the optimum tilt (33° for central Antalya), is chosen. There are systems with seasonal adjustment, but fixed tilt is mostly preferred in roof systems. For tilt and orientation, see solar panel tilt and orientation in Antalya.

Do solar panels work in cloudy weather?

Yes, they work, but produce less. Panels generate electricity not only from direct sunlight but also from light that passes through and is scattered by clouds. Because cloud reduces light intensity, output falls; how much depends on the thickness and type of the cloud, so giving a single percentage would not be right. On a day with thin cloud, output may drop only a little, while under dense rain cloud it falls markedly.

Another effect of cloudy weather is that output jumps around within the hour. As clouds pass, power fluctuates; inverters track this change. This is normal and does not mean a fault. Cold weather is also an advantage for the panel: in a TOPCon panel with a temperature coefficient of -0.30 %/°C, power rises as cell temperature drops. In winter the cells do not reach 65 °C as they do in summer; so at the same irradiance, efficiency per unit of light is better in winter. Still, because irradiance is much lower in winter, total output is lower than in summer.

Rain, snow and winter care in Antalya

Winter rain provides natural cleaning by washing the panel surface. According to MGM, most rainfall comes between November and February and the annual total is about 1,032 mm. For this reason, panels are mostly free of summer deposits by the end of winter; soiling causes more trouble in the summer months. For details, see dust, pollen and panel soiling in Antalya.

Snow is rare in central Antalya and on the coast; according to MGM records the greatest snow depth is 5 cm (07.01.1993). The typical snow-load resistance in panel datasheets is 5400 Pa. In high-altitude districts, for example around Elmalı and Korkuteli, snow depth and duration may differ, so local snow load is assessed separately for these areas. As an interesting detail, according to PVGIS, Elmalı's annual specific yield of 1,719 kWh/kWp is the highest among the districts on the list; in other words, high-altitude districts also offer good production potential.

Worked example: the winter share of a 5 kWp system

If we take the annual specific yield as 1,656 kWh/kWp, the annual expectation for a 5 kWp system is about 8,280 kWh (5 x 1,656; calculation). In December, January and February a total of about 1,530 kWh (5 x 306) is expected, while in June, July and August about 2,470 kWh (5 x 494) is expected. These figures are based on PVGIS assumptions; actual output varies from year to year and this is not a guarantee of production or savings.

This example shows that the system does not disappear in winter; its share just gets smaller. About one fifth of total production happens in the winter months; the rest of the year, especially spring and summer, carries the main load. For this reason, payback calculations should be based on the annual total, not on winter.

Preparing for winter: what should you do?

• In autumn, before the rainy season, visually check the panel and mounting structure connections.
• Check for shading: because the sun is low in winter, the shadow of a building or tree that causes no problem in summer can affect panels in winter.
• Make sure the inverter and monitoring system are working and that there is no fault record.
• Set a realistic expectation for winter output: use the PVGIS monthly values as a reference.
• In hybrid or off-grid systems, check battery capacity against winter consumption.

For the winter-specific effect of shade, you can also read our article on the effect of shading on solar panels.

Winter consumption and net metering: setting expectations correctly

While output falls in winter, consumption can rise with heating and lighting needs; in Antalya this difference is clear in homes where air conditioners are used for both cooling and heating. So you need to know from the start that your electricity bill in winter may not fall as much as your summer production allows. The healthiest approach is to size the system to annual consumption while accepting that not every month will be covered to the same extent.

How surplus production is treated depends on regulation and may change. As of October 2026, net metering (mahsuplaşma) is monthly for residential subscribers and has been hourly for new non-residential installations since 1 May 2026. For the details of these rules and current tariffs, see what is a net metering system; confirm up-to-date information for your own case with the distribution company. In hybrid systems, the battery's winter performance is a separate topic; it helps to choose the capacity so that energy accumulated during the day is used in the evening.

Design decisions that improve winter output

A few design decisions improve the winter share to some extent. South-facing placement is the direction that best captures the low winter sun. Choosing an unshaded area matters even more given that the winter sun is low. In string design, attention must be paid to the start-up voltage so that the inverter can begin working even at low irradiance. Bifacial panels can provide extra gain on certain surfaces by also receiving light on the rear side; however, the gain depends on ground reflectivity and remains limited in roof systems.

In hybrid systems, the most important decision for winter is battery and inverter capacity. When winter night consumption and short days are considered together, the battery's daily cycle differs from summer. Our article on the hybrid solar energy system gives details on this.

Conclusion

Solar panels in winter keep working in Antalya; according to PVGIS, December output is about 59 percent of July's. Cloud reduces output but does not stop it, cold weather raises cell efficiency, and winter rain cleans the panels. The right approach is to look at annual total production and to see the winter drop as a seasonal phenomenon, not a fault. If you want a realistic production estimate for your own roof, you can request a free site survey through our contact page.

#Maintenance and Efficiency#Winter Output#Pvgis#Cloudy Weather#Performance#Antalya