As the days shorten and the sun hangs lower in the sky, it’s crucial to optimise your solar setup to maximise its performance through the colder months. Here’s a guide to preparing your solar panels for winter, from panel alignment to managing household electricity loads.
The Power of Alignment and Split Arrays
While a south-facing roof is the ideal for year-round solar production, a split array with panels facing both east and west can be a powerful strategy for winter. This setup captures sunlight from morning until late afternoon, extending your generation window. For winter months in the UK, the optimal panel tilt angle is around 50-52 degrees from the horizontal, which is steeper than the 20-22 degrees recommended for summer. This steeper angle helps catch the lower winter sun more effectively. While a fixed roof angle may not allow for this, the concept of capturing light throughout the day with a split array is key to maintaining a higher output from your solar investment.
Tackling Household Power Loads
Winter sees an increase in electricity consumption due to longer hours of darkness and more time spent indoors. It’s essential to be mindful of key power-hungry items:
- Central Heating Pumps: These are often overlooked but can be significant energy users. A typical domestic central heating pump uses around 50 watts, but modern high-efficiency pumps can use as little as 2-3 watts. The power consumption is highly dependent on the pump’s speed setting.
- Lighting: As evenings draw in, lighting use increases. Switching from traditional bulbs to modern LED bulbs is a simple and effective way to cut down on electricity use. For example, a single traditional 60W bulb can be replaced with an LED equivalent that uses just 7-10W.
- Cooking: Preparing more hearty, warm meals can also increase electricity usage. While an electric oven can use around 2.2 kW, more efficient appliances like air fryers or slow cookers use considerably less power.
Making the Most of Night-Time Tariffs
During the winter, you’ll likely need to import more electricity from the grid. A smart meter and a time-of-use tariff can help you significantly reduce costs. These tariffs offer cheaper electricity rates during off-peak hours (typically at night). Here are some examples of suppliers and their time-of-use tariff offerings:
- British Gas: Their “Electric Driver” tariff offers cheaper rates from 12am to 5am, which is ideal for charging an electric vehicle or running appliances with a timer.
- OVO Energy: They offer a “Charge Anytime” add-on for EV owners, which gives a discounted rate for EV charging.
- Octopus Energy: They have several smart tariffs, including “Octopus Go” for EVs and “Octopus Flux,” which pays you more for exporting power to the grid during peak times and charges less at off-peak times, making it excellent for homes with batteries.
Projected Decline in Solar Production
To help you manage expectations, here is a projection of the percentage decline in solar production for a 6kW solar array in the UK, using May as a 100% reference. These figures are based on average UK solar insolation data and will vary by location.
| Period (Two-week blocks starting from end of August) | Approx. Percentage Drop in Production vs. May |
| Late Aug – Early Sep | 20-25% |
| Mid Sep – Late Sep | 30-35% |
| Early Oct – Mid Oct | 40-45% |
| Late Oct – Early Nov | 55-60% |
| Mid Nov – Late Nov | 65-70% |
| Early Dec – Mid Dec | 75-80% |
| Late Dec – Early Jan | 80-85% |
The Winter-Aligned Array Boost
Adding a second, smaller array can significantly boost your winter production. By aligning a 2kW array to the optimal winter angle and direction (steeper and more southerly), you can capture more of the low winter sun. This can add a significant boost to your overall solar installation, helping to offset the dramatic drop in production from your main array and reduce your reliance on grid electricity when you need it most. This strategy is particularly effective for households with a larger winter electricity demand or a smaller roof top solar array.
If you have a battery installation this could mean adding a solar charge controller to the battery pack terminals and to the solar panels to directly top up the battery while the main array may not provide sufficient power, the second array will boost the power available.
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