How Much Energy Do Solar Panels Generate?

Solar panels are an increasingly popular energy solution, but many people wonder how much energy they actually generate. The amount of energy your system generates depends on factors such as sunlight exposure, roof orientation, panel efficiency and the number of panels installed. To learn more about the best setup for your home, see our guide on the right roof placement for solar panels.

How Much Energy Does A Solar Panel Generate?

On average, a typical solar panel in the UK generates between 250 and 400 watts per hour during peak sunlight. If you’re wondering how much a solar panel can generate electricity in a day, this usually adds up to about 1.5 to 2.4 kilowatt-hours (kWh) daily, depending on your location and the weather.

To put this in perspective:

• One solar panel can power a fridge for almost an entire day.
  
  
• You could use a laptop for up to 30 hours with the energy from a single panel.
  
  
• It’s enough for 15 to 24 hours of television, or dozens of cups of coffee brewed.

Over a year, each panel produces roughly 350 to 425 kWh.

Want to know how many solar panels are right for your home? Read our guide on How Many Solar Panels Do You Need?

How Do I Calculate Solar Panel Output?

Calculating how much electricity your solar panels can generate is simpler than you might think. The main things you’ll need to know are the panel’s wattage, its efficiency, your location and how much direct sunlight your roof gets.

To estimate your solar output:

• Find the size of one solar panel (in square metres)
  
  
• Multiply by 1,000 (to convert to watts)
  
  
• Multiply by the panel’s efficiency (as a decimal)
  
  
• Multiply by the average daily sun hours your roof gets
  
  
• Divide by 1,000 (to convert to kilowatt-hours, kWh)

Example Calculation

Say your panel is 1.7 square metres, 20% efficient, and your area gets 4 hours of good sunlight a day:

1.7 × 1,000 = 1,700
1,700 × 0.20 = 340
340 × 4 = 1,360
1,360 ÷ 1,000 = 1.36 kWh per day

To estimate your monthly output, just multiply the daily result by 30.

Tip: Sunlight hours change with the seasons, so your output will be higher in summer and lower in winter.

How Many kW Do I Need to Run a House?

The amount of solar power needed for a home depends on the size of the property, the number of people living there, and how much electricity you use each day. On average, here’s what different homes in the UK might need:

A typical high-efficiency solar panel in the UK produces around 265kWh per year. So, to meet your home’s needs, you’ll want a system that matches your yearly energy consumption.

For example, if your home uses 3,500 kWh a year, and each panel produces 400 kWh annually, you’d need about 9 panels to cover your electricity use.

What Happens If My Solar Panels Aren’t Producing Enough Energy?

If your solar panels aren’t generating enough energy, your home will automatically draw what it needs from the grid. Your lights, appliances and devices will keep working as normal. You’ll just use more energy from your supplier, which could mean slightly higher bills.

If you want to improve your solar output, you can:

• Check your inverter or monitoring app to see if the dip is recent or ongoing.
• Book a professional inspection. A technician can check for technical issues, loose connections or damaged panels.
• Explore system upgrades. Adding battery storage means you can use more of your own solar power later in the day when you’re not generating as much electricity.
• Think about your energy use. Simple changes, like running your washing machine when the sun’s out can help you get the most from your system.
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If you’re unsure, reach out to your installer or a certified solar expert. They’ll help you understand what’s happening and guide you on the best next steps.

Are My Solar Panels Working Efficiently?

If you want to know how much electricity your solar panels produce and whether they’re running at their best, it’s easy to keep track. Most solar panel systems come with a digital display or a monitoring app that lets you see real-time performance and energy output, right from your phone or tablet.

Check your energy generation daily, monthly, or even yearly to spot any changes. If your panels suddenly produce much less than usual (especially on sunny days), it’s a good idea to look for anything that could be blocking sunlight, such as dirt, leaves or new shade from nearby trees. Many monitoring tools can even send you an alert if your system’s output drops below expected levels.

For peace of mind, compare your recent energy data with past performance. Consistently strong output is a sign that your system is working efficiently. If you notice unexpected dips or have questions, a certified installer can help you investigate and get everything back on track. Regular monitoring helps you get the most value from your solar investment and ensures your panels are delivering clean, reliable power year-round.

Comparing Solar Energy Production with Traditional Energy Sources

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Solar energy production offers various advantages compared to traditional energy sources. Let's explore a few comparisons:

Solar vs. Fossil Fuels

Solar power is clean, renewable and produces no greenhouse gas emissions during use. Fossil fuels, by contrast, are a major source of carbon emissions and air pollution in the UK and they’re running out. A single solar panel can generate 1 kWh of electricity without releasing any emissions. In fact, a typical 4 kW solar panel system in the UK can produce around 3,350 kWh of electricity per year, helping you reduce your reliance on the grid and fossil fuels.

Solar vs. Wind

Both solar and wind are renewable energy sources, but their performance varies with location and weather. In terms of residential output, a typical home solar panel generates 250–400 watts, while a small wind turbine might generate 1–2 kW, but only when the wind blows steadily at high speed.

Solar panels offer more predictable output, especially during daylight hours, and are easier to install on most UK homes. For the average home, installing 8 to 12 solar panels can cover most annual electricity needs. Wind turbines need much more space, and most need planning permission, and they’re much noisier than solar.

Solar vs. Hydro

Hydropower uses the force of water to generate electricity, often at a much larger scale. For comparison, the world’s biggest hydroelectric dam, Three Gorges Dam in China can generate 22,500 MW, enough to power millions of homes.

While hydropower is extremely efficient where geography allows, it isn’t a practical solution for individual households. By contrast, a home solar panel system generating 3,000 to 4,000 kWh annually is a realistic and accessible choice for many UK homes, offering reliable energy and real cost savings.

Maximising Solar Panel Energy Output

To maximise the energy output and lifespan of solar panels, here are a few tips:

‍Optimal Installation and Positioning

Proper installation and positioning of solar panels are crucial for best performance. Our professional team makes sure your panels are installed in the best position on your available roof space to capture as much sunlight as possible.

Learn more about solar panels:

A guide to solar panel maintenance‍

Do solar panels work in the winter‍

Pros and cons of solar energy

Battery Storage and Smart Grids

Adding battery storage solutions to your solar system allows you to store excess energy generated during the day and use it during periods of low generation. A typical home battery in the UK holds between 4 and 13 kWh – that’s enough to cover your essential needs after dark.

Ready to See How Much Energy Solar Panels Could Produce for Your Home?

Want to know how much electricity you could produce and how much you might save each year? Solar panels put you in charge of your energy bills and help cut your carbon footprint, all by using the free, renewable power of the sun.

Get Your Personalised Solar Panel Estimate

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