How Much Electricity Does A Solar Panel Produce?

How Much Energy Does A Solar Panel Generate?

There are dozens of factors that affect how much electricity a solar panel produces. One of the most important is the panel’s efficiency. 

Low-grade panels offer efficiency ratings of under 20%. However, if you use a high-grade panel such as the LONGi Hi-Mo X6, you’ll see an efficiency rating of 23.2%. 

One of the most common solar panel sizes is 400w:

• At 23.2% efficiency, you’d expect that panel to generate 92.8 watts per hour
• With a typical system using approximately system using 12-panels, this figure rises to 1.114kW per hour 

Solar panels will only generate electricity during daylight hours and will produce the most during sunlight hours. 

As this varies on the day, season and even where you are in the country, it’s hard to pin-point exactly what a system is likely to produce. 

As you can see over at Statista, you’d expect to see about 4.5 sunlight hours per day on average: 

With your solar panel system producing 1.114kW per hour and roughly 4.5 sunlight hours in a day, you’d expect around 5kWh of electricity to be generated each day. 

That’s going to mean your system produces approximately 152kWh per month, or 1,825kWh per year.

Our solar panel tool here takes into account your energy usage to determine what size solar panel system you need, and indicates potential energy savings. 

How Much Electricity Do I Need My Solar Panel System To Produce?

Now you know how much energy an individual solar panel and a complete system is going to produce, the next question is, how much do you need? 

According to Ofgem, a medium usage household will consume around 2,700kWh per annum. A high consumption household would be using approximately 4,100kWh of electricity per annum. 

Based on the above system estimates, electricity generated using 12 x 400w solar panels would mean: 

• 67.6% of electricity consumed for a medium consumption household, would be covered by solar panels
• 44.5% of electricity consumed by a high consumption household, would be covered by solar panels

To hit these figures, it’s likely you’d need a small-medium solar storage battery. 

Whilst your panels will produce a reasonable amount of electricity, the system is most productive during the day, whereas the majority of electricity is consumed during mornings and evenings. 

With a solar storage battery, excess electricity produced during daylight hours can be stored for use later.

A small 5kW battery is likely to cost anywhere from £2,495-£3,495 depending on the installer.

We provide fixed prices for systems via our solar panel page here. 

There, you’ll be able to flick between options including small, medium and large storage batteries. 

Factors That Affect Solar Energy Production

The amount of energy solar panels produce varies depending on a range of factors from: efficiency, the type of inverter you use, roof pitch and even the amount of sunlight hours your roof gets.

Solar Panel Efficiency

As we mentioned above, a high-grade panel like the Hi-Mo 6 from LONGi operates at 23.2%, whereas low-grade panels operate at 20% or less. 

But as you can see from this graphic, degradation rate (the drop in efficiency over time) is an important consideration too: 

Whilst many manufacturers will offer a product warranty of 25-years, what you actually want, is a “performance warranty”. This covers a maximum degradation rate. 

In the case of LONGi’s Hi-Mo 6 Guardian, it’s 1.5% in year 1, then 0.4% in years 2-25. 

Ultimately, that means your solar panels will still operate at 88.9% efficiency in year 25, or be replaced via their performance warranty!

Get quotes on your system, inclusive of high-quality panels with a performance warranty using our solar panel tool here. 

Type of Inverter

There are 3 types of inverter: string, micro and hybrid. 

Of the 3, string inverters are the most inefficient. If any panel in a “string” is damaged or shaded, all panels on the string are affected. You’ll see a huge drop in efficiency and ultimately, a drop in how much electricity solar panels produce.

For that reason, you’ll want a system that uses high quality micro or hybrid inverters. If any individual panel is lacking efficiency (due to shading or damage), only that panel will be affected. 

Use our solar panel quotation tool to get prices on your system including a hybrid inverter.

Or, read more about the different types of solar inverters here.  

Roof Pitch & Orientation

Not all roofs are suitable for solar panels.

Put simply, the optimum roof setup is one that's at a 30° pitch and facing due south. 

This graphic produced by the Energy Saving Trust shows how a different roof pitch or orientation can affect how much electricity solar panels generate: 

We’ve got a detailed guide to roof suitability for solar panel systems here. 

Unsure if your roof is suitable for solar panels? Contact our solar energy experts here. 

Sunlight Hours

We’ve mentioned that you should expect around 4.5 sunlight hours per day. That’s when your solar panels will be producing the most electricity. 

But as you can see from this graphic produced by ResearchGate, this figure varies depending on where in the UK you’re based: 

According to this data, expect sunlight hours to be as low as 1.98 per day, up to 5.13 per day. 

Living in the sunniest part of the UK? You could be generating up to 2.59x the amount of electricity via your solar panels as a property in the darkest parts of the UK!

Maintenance

Solar panels generally need very little maintenance. However, it’s advisable to get them cleaned on a regular basis. 

Any build up of dust, dirt or bird droppings is going to drastically reduce their efficiency. And as a result, their energy production is going to drop dramatically too. 

Which Are The Best High Efficiency Solar Panels?

The most efficient solar panels come from brands such as: 

Whilst cheap solar panels are likely to operate at lower than 20% efficiency, many of the brands above operate at 22% or higher. 

As we mentioned above, we fit solar panel systems using the likes of LONGi, which provide efficiency ratings of up to 23.2%. 

For a 12-panel system that’s 5kW or higher, expect to pay just under £6,000 including installation costs (but not including a storage battery). You can read our full guide to solar panel costs here. 

Get a quote on your solar panel system and maximise electricity production using the most efficient panels by using our clickable tool here. 

Storing Excess Electricity

How much electricity a solar panel produces shouldn’t be your only concern. 

Most electricity will be generated during the day. On the flip-side, the times of biggest consumption are usually in the mornings and evenings. 

To make the most out of your system, you’ll want a solar storage battery.

Solar storage batteries help to increase your energy self-sufficiency, with any excess electricity generated, being stored for later. 

Still got questions? 

• Speak to our experts here
• Read our guide to solar panel installation here
• Get quotes on your system here. 

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