Do solar panels work in winter — and how much do they produce
Yes, they do. But output drops 60-75% compared to summer. A 5 kW system in Kyiv generates 650-750 kWh/month in summer and 100-160 kWh in December. This is normal and factored into system design.
Winter is the weakest season for solar generation in Ukraine. Shorter days (8 hours vs 16 in summer), low sun angle, frequent cloud cover, and snow. But "weak" does not mean "zero".
Winter generation by region
| City | December (kWh/kW) | January | February |
|---|---|---|---|
| Odesa | 35-45 | 40-50 | 55-70 |
| Dnipro | 30-40 | 35-45 | 48-65 |
| Kyiv | 20-32 | 25-35 | 40-55 |
| Lviv | 18-28 | 20-30 | 35-48 |
| Kharkiv | 25-35 | 28-38 | 42-58 |
February is noticeably better than December. March is already "spring" for generation (80-100 kWh/kW).
Why winter output is lower — three reasons
1. Short daylight
December in Kyiv has ~8 hours of sunlight (4-5 effective). Summer has 16 (8-10 effective). This factor alone cuts generation in half.
2. Low sun angle
In winter the sun stays below 15-20° above the horizon. Rays hit the glass at a sharp angle — more light is reflected.
3. Cloud cover
November through February are the cloudiest months. In Kyiv and Lviv, 70-80% of days are overcast or partly cloudy. Panels still generate from diffuse light, but at 10-30% of potential.
Snow — friend or foe?
- Snow on panels — foe. Even a thin layer cuts generation by 80-100%. At 25°+ tilt it slides off within 1-2 days.
- Snow around panels — friend. Snow reflects 80-90% of sunlight. Bifacial panels get a serious boost from snow albedo — up to 30-40% extra rear-side generation.
Manually clearing snow is risky. Better to wait for it to slide off. Exception: frozen ice on flat panels.
How to maximise winter output
- Optimal tilt angle — winter ideal is 55-60°. The year-round compromise of 30-35° works acceptably.
- Clean panels — wash before winter. Every percent of transparency counts when sun is scarce.
- Minimise shading — trim tree branches. In winter with low sun, even short objects cast long shadows.
- Battery storage — winter days are short and evening consumption rises. LiFePO4 battery stores daytime generation for evening and night use.
- Oversize the system — for full winter coverage, plan 1.5-2x the annual average requirement. Or accept that 40-60% of winter electricity comes from the grid.
Temperature and efficiency — the winter bonus
Here is a surprise: cold is good for solar panels. Lower temperature raises efficiency. A temperature coefficient of -0.35%/°C means at -10°C the panel generates 12% above its rated power compared to the standard +25°C test condition.
On a frosty sunny day, panels can output 110-115% of rated wattage — something impossible in summer due to heat. This partly offsets winter losses.
Frequently Asked Questions
Do panels generate enough in December for a house?
For full coverage — usually not. A 5 kW system in Kyiv produces 100-160 kWh in December against 400-600 kWh consumption. But it covers 25-40% of the need.
Should I tilt panels steeper for winter?
Ideally yes — 55-60° in winter. But adjustable mounts cost more. The 30-35° year-round compromise works well.
Will frost damage solar panels?
No. Quality panels are rated from -40°C to +85°C. The glass is tempered, the frame is aluminium. Cold actually boosts efficiency.
Does a hybrid inverter work below zero?
Most operate down to -25°C. However, LiFePO4 batteries must not be charged below 0°C (discharging is fine). Keep the battery in a heated space.
Does snow affect the warranty?
Snow loads up to 5,400 Pa are within warranty spec. That is roughly 1.5 m of wet snow.
Summary
Winter generation is 25-40% of summer output. Battery storage, proper tilt, and clean panels help extract the most. Cold weather actually boosts efficiency. Browse our solar panel catalog and use the calculator for winter balance estimates.
