How much energy can solar panels produce?

More and more homes are installing solar panels. They’re no longer a concept that sounds strange or unknown to us. But with increasing numbers of people opting ​​for clean and renewable energy sources, such as solar energy, it’s important to look at how much energy can be produced.

In this guide, we talk about the performance of solar panels. We’re simply referring to the ability of the solar panel to transform energy from the sun into electrical energy suitable for domestic consumption. The higher the percentage of performance, the more energy is produced.

In recent years, the average efficiency of converting solar energy into electricity has increased as technology has improved. However, not all photovoltaic solar panels perform the same. Performance can be impacted by different factors, such as the materials of the modules, their orientation or the weather. In this guide, we look at exactly how much energy solar panels can produce, as well as how to maximise performance.

Do solar panels produce enough energy to power a house?

Solar panels have the potential to produce enough energy to power a house, depending on the size of the home, average energy consumption and number of panels installed, as well as the amount of sunlight available at its location.

Larger solar panel installations in areas with plenty of sunshine could generate enough electricity to meet all, or nearly all, of a house's daily needs. The amount of solar panels needed really depends on the size of the house, and how much electricity is needed – a smaller property with lower energy consumption could be powered by a smaller installation. For larger properties, solar may need to be combined with other renewable sources, such as wind and hydropower, or electricity from the national grid to ensure the property receives an adequate supply of energy. It largely depends on how much energy the home is using. For example, if you work from home, your energy usage is likely to be more.

Even if solar power only covers part of a home's energy consumption, it can still save homeowners a considerable amount of money. For example, a 4.3 kWp system without a battery installed in Surrey could offer a saving of around £943 per year, and an average saving of £23,500 over a 25-year period, based on:

• Annual kWh production of 4112
• Annual self-consumption of 2056 kWh
• Annual consumption of 1594 kWh from the grid
• Annual surplus of 2056 kWh sold to the grid
• An average spend of £3,650 before solar panels were installed

Solar panel energy production

When discussing how much energy solar panels produce, two measurements are important:

• Kilowatt-hours (kWh)
• Kilowatts peak (kWp or Wp)

Solar panels convert sunlight into electricity, which can be measured in kWh. It’s equal to one kilowatt (1,000 watts) of power used for one hour. Generally, a 1kW solar panel system can produce between 3 and 5 kilowatt-hours of energy per day (depending on conditions).

Larger solar arrays, made up of numerous panels, are typically capable of producing more energy than smaller systems since they cover a larger area and can absorb more sunlight and convert it into usable electricity. They’re also capable of a greater peak, since there are more panels to capture the sun’s radiance.

The term kilowatts peak refers to the power generation capacity of a solar module. It’s the measurement which lets you know the peak power of a system or panel; the rate at which they will generate energy at peak performance and in optimal sunlight conditions. At Otovo, we provide quotes for systems ranging from around 1.9 kWp to upwards of 5.9 kWp.

The amount of sunlight received will have one of the biggest impacts on performance, and it does vary by month and location as shown below:

Monthly output in Surrey

Monthly output in Newcastle

How to maximise energy production

Several factors affect the efficiency and performance of solar panels. It’s important to take these aspects into account to get the most out of your installation, generating the most energy possible and extending its useful life to enjoy the clean energy of solar power for as long as possible. The factors that’ll cause energy production to increase or decrease are:

Photovoltaic installation materials

The energy produced by solar panels will depend on the materials that they’re composed of. Higher quality materials typically lead to more profitable panels. Monocrystalline panels tend to be better than polycrystalline for these purposes.

Not only are the parts present in the modules important, but the rest of the components involved in the installation of the photovoltaic system such as the inverter, the wiring and the battery all contribute to how much energy is produced. At Otovo, we work with brands such as JA Solar, SunPower and FuturaSun that offer high performance photovoltaic solar panels and recognised quality.

Temperature and climate

Performance is affected by the climate of the geographical area where the solar installation is located. It’s not all about a hot climate, however. The importance lies in the number of hours of sunshine per year received by the area as solar panels have been created to get the maximum possible energy from the sun – not temperature. In fact, very high temperatures aren’t favourable for energy production.

Another myth is that solar panels aren’t feasible in cloudy weather. Technological advances produced in the solar energy sector have been impressive, generating high-quality solar panels that can resist adverse weather conditions. In fact, rain or snow can be beneficial. Here’s a look at some considerations for installations which maximise energy production, whatever the weather conditions:

• Wind. It’s important to be careful installing panels in areas where the wind is very strong, since the force exerted on the surface of the solar panels can cause damage. It’s necessary to have high-quality materials and adequate anchors that are resistant to a potential sail effect. This can happen because the flattened shape of solar panels makes them more vulnerable to the action of the wind, making the selection of a professional installation company critical.
  
• Cloudy conditions. There is a widespread misconception about the performance of these systems on cloudy days. It’s true that direct radiation from the sun will have a more positive effect, but solar panels also work with diffuse radiation because the rays of sunlight pass through the clouds and reach the surface of the solar panels.
  
• Snow. Snow actually reflects sunlight, improving the performance of the photovoltaic system.

Solar irradiation and geographic location

As we’ve discussed, the climate (notably the sunlight hours) will influence the solar irradiation. That is, the weather will cause more or less radiation to reach the surface. There are three types of radiation:

• Direct radiation comes directly from the sun and the amount received will depend on the clouds and the time of year, as well as where the solar panels are located.
  
• Diffuse radiation is the sunlight that has been scattered by particles in the atmosphere such as water molecules, dust, and pollutants. It can be collected regardless of the direction of the direct beam of sunlight hitting a given area as this type of solar radiation is reflected off objects in its path and does not depend on any type of concentrated energy source in the way direct radiation does.
  
• Reflected radiation. This type of radiation is produced by bounced or reflected radiation from the surface. Only houses located perpendicular to the earth's surface receive this type of radiation.

Each geographical area of ​​the country will receive different amounts of solar radiation, directly influencing the performance of the solar panels.

Shadows are another important aspect that will greatly affect the performance of solar panels and that must be taken into account in any photovoltaic installation. Shadows on solar panels should be avoided because they’ll have a negative impact on the amount of energy produced, although it is sometimes difficult in certain homes where space availability is quite limited. Optimisers are a good option to monitor the performance of each module, optimising efficiency and mitigating against any loss of energy capture.

Orientation and tilt

In order to achieve the maximum performance from solar panels, we must take into account the orientation and inclination of the array.

The most recommended orientation for solar panels is south-facing. When we orient the solar panels to the south, the perpendicular rays reflected on the surface allow an increase in their productivity and, therefore, also increase the profitability of the system.

Houses which face east will only receive sun in the earliest hours in the morning, whereas west-facing properties will get the most sun towards the late afternoon. In both cases, the energy generation will be lower than in the houses that are south facing.

A very common solution to compensate for this fact is, in homes that allow it, to install panels to both east and west, thus largely replicating the production of a south orientation.

Maintenance

Dirt collecting on solar panels as a result of weather or pollution will reduce the performance. Fortunately, keeping solar panels clean and in good condition doesn’t require a considerable investment of time or money.

The resistant materials used in the manufacture of solar panels allows them to maintain quality standards despite any dirt and debris experienced. As a result, cleaning is a very simple process. You’ll only need water and a sponge to remove dirt from the surface around three or four times a year.

The other aspect of solar panel maintenance is replacing any system parts that are in poor condition or have a fault. Keeping your panels clean and checking for any damage or faults ensures you’re able to extend the useful life of the photovoltaic system and generate greater production of solar energy.

Seasonality

We can’t deny that solar panels receive a greater amount of sunlight, generating greater energy production, in the summer months. But this doesn’t mean that an installation isn’t profitable in winter. Seasonality is simply another factor to take into account in solar self-consumption systems, but we shouldn’t worry about their performance because solar panels capture energy from sunlight and performance is not based on the heat received.

The performance of solar panels in winter is reduced due to the lower number of hours of sunshine received per day because the days are significantly shorter. The position of the sun will also vary, impacting in a less direct way on the solar panels.

FAQs

Do solar panels work in winter?

Yes, solar panels work in winter. The yield won’t be significantly affected, but the panels will produce less energy due to fewer hours of sunshine at this time of year.

Do solar panels work in cloudy weather?

Solar panels do work in cloudy conditions, but the energy production tends to be between 10% and 25% of its capacity. The sun's rays pass through the clouds, allowing them to reach the surface of the solar panels and, in this way, continue to generate solar energy for self-consumption.

Do I need to tell my electricity supplier I have solar panels?

Yes, you will need to inform your electricity supplier when you install solar panels on your home. Depending on the company, there may be additional paperwork that needs to be completed.