Solar Panels Buyers Guide

At EvoEnergy, we’ve put together a buyers guide to solar panels to help you learn more about how solar works, how you can benefit, and how you can ensure it is the right choice for you. We want our customers to be as informed as possible to support you making the best desicion.

Solar panels costs, benefits and installation information

Solar panels (photovoltaic) capture energy from the sun and turn it into usable energy for your home or business.

Solar thermal and solar pv are fundamentally different, however they are both capable of saving electricity/heating costs and carbon dioxide, as well as being able to earn a residual income for a period of 20 years from their installation.

This guide will cover the following areas:

  • An introduction to solar energy
  • The benefits of solar
  • Costs, savings and maintenance
  • How solar panels (PV) cells work?
  • Is your property suitable for solar?
  • Choosing the right solar panels for your property
  • A little more about getting solar panels with EvoEnergy

An introduction to solar energy

Solar PV

A solar PV system works using a number panels (an array), which is normally mounted on the roof. Each solar panel is made up of photovoltaic cells. These are usually made of wafer-thin layers of silicon and look a bit like blue or black tiles. When daylight hits the cells it creates an electric field. The brighter the sunlight, the more electricity is produced. This direct-current (DC) electricity then flows to an inverter, which converts it into alternating current (AC) electricity for you to use.

How solar panels work from sunlight to AC power

Introduction to Solar Electricity

If you have a solar PV system installed at home, it will automatically feed the power you’ve generated to your appliances, so a lot of the power you use during the day will be free. During the night times, or if you use more energy than you produce, your power supply will switch back to the grid. You won’t notice any disruption or change – just smaller bills. To make the most of all that free electricity, it’s best to use appliances like dishwashers and washing machines during the day. The system can’t store electricity, so if you produce more than you use during the day, any excess will be fed into the national grid for others to use.

Solar PV is a great investment for the future. Not only will it help you save on energy bills and protect you against rising fuel prices, it will also generate a tax-free income through the government’s feed-in tariff payments.

Solar thermal

Solar thermal panels work differently, but are also commonly found in arrays on roofs. They absorb heat from the air, which in turn heats water in a closed loop to heat your hot water cylinder. Thermal systems are complementary to your normal gas fired boiler, but will reduce your annual gas consumption by up to 50%.

Update; please note that we now no longer supply or install solar thermal.

The benefits of solar

In the UK, there are huge financial benefits for installing solar panels including energy bill savings and protecting you against future energy price rises. The Government also financially support solar panels installations with the feed-in tariff, summarised below.

The feed-in tariff (FiT)

The feed-in tariff for solar PV has been in place since April 2010 in the UK with the tariff comprising of two payments; the generation tariff and the export tariff.

How the Feed-In Tariff Works

How the Feed-In Tariff Works

The generation tariff pays you for each unit of electricity that your system generates, whereas the export tariff pays you for every unit of electricity you export. To keep things simple, most electricity companies assume you’ll use 50% of your generated electricity, and pay accordingly. Larger projects can be individually metered to ensure that payments are correct.

Most homeowners are capable of getting annual returns on their investment in the region of 12%. To see the latest information on the feed-in tariff, visit our feed-in tariff page.

The feed-in tariff rises annually in line with inflation. Each quarter, the feed-in tariff is aligned to closer fit with grid electricity prices, but you will receive the full payment of the tariff that was available when you signed up for the full 20 year term.

Costs, savings and maintenance


Residential solar PV systems vary in size, usually upwards from around 1 kWp (about 4 panels) and generally up to 4 kWp, but is not uncommon for this to be higher for larger homes. Systems start from a little over £4,400, with our average sized system for homeowners being around 3.2 kWp.

The main costs associated with the installation is the solar panels themselves, but we also factor in cabling, mounting frames and labour costs, along with our range of warranties.


As well as the payments you’ll receive from your electricity provider, you will also see a benefit from bill savings through installing solar panels.

The total benefit of the system can be calculated by a simple calculation;

Generation Tariff + Export Tariff + Bill Savings = Annual Benefit

Energy prices are destined to rise dramatically year on year, so this annual benefit will rise significantly.


Solar panels need little maintenance due to their surface and mounting position. Rain water is usually enough to keep the panels clean, but many of our customers want to ensure that they are performing at their optimum, and as a result we’ve heard of lots of window cleaning companies offering a solar panel cleaning service.

You can usually clean your panels for the same cost as a series of Velux windows, with no specialist equipment.

How solar panels (PV) cells work?

How solar panels work from sunlight to AC power

How Solar Panels Work

A solar pv system is made up of several components; solar panels, an inverter, a meter and your consumer unit – along with a few meters of cabling.

  1. Usable light hits the panels, even on cloudy days
  2. The photovoltaic (PV) cells in the panel convert the light in to usable DC electricity
  3. The DC runs down a cable to the inverter, which converts the current to AC which is usable in the home
  4. The current is fed through a meter and then into your home’s consumer unit
  5. Plug in and switch on. Your system will automatically use the free electricity you’ve generated, then switch back to the grid as needed
  6. Any electricity you don’t use is exported to the grid for others to use, and you’re still paid for the electricity you generate but don’t use

The energy you generate on your roof will feed the demand at your property before any energy is supplied by the grid, so if your generation is higher than your demand your electricity meter will stand still and you’ll be operating your home for free!

Solar radiation

Solar radiation is seen by us as visible light. The blue end of the light spectrum is usable by solar electricity panels, and the red (heat) is usable by solar thermal panels. Levels of solar radiation differ from location to location, so regional performance differences are to be expected. We use the conservative BRE SAP 2009 method of estimating output for all solar panel systems we quote and install.

Is your property suitable for solar panels?

Solar panels are suitable for most properties in the UK. A perfect roof for solar would be large, south facing and pitched at around 30-45°. However, with a correctly designed system with the most appropriate solar panels, even a less-than-perfect roof can get a brilliant output.

There are a few simple points to consider, but we’ll be able to help design the perfect solution.

Which way does your roof face?

The direction that your roof faces influences the amount of sunshine that it receives throughout the day. Due south is a perfect location for a system of either pv or thermal, but systems are viable up to an east-west split. We don’t normally install on a north facing roof due to the lack of irradiance.

East or west facing roofs achieve only 15% less output compared to due south systems.

What’s the angle of the roof?

Having panels installed between 30° and 45° is optimal, but they can work well at any angle around this. On flat roofs, we mount panels to a framing system to provide an optimal mounting angle.

Is there enough space for the solar panels?

Solar panels are relatively new technology, despite being around for many decades. Efficiency of the panels is always increasing, so the required amount of space continues to decrease. We’re currently look

How energy efficient is your home?

As of April 1st 2012, the government made a requirement to have an energy efficient home, rated at EPC rating D or above. Energy Performance Certificates (EPC) measure the efficiency of your home, and a number of efficiency and renewable measures can improve your score. As long as you can reach grade D or above, you’ll get the full feed-in tariff rate.

It’s estimated that approximately 50% of the current UK housing stock already meet grade D, but a few older houses may need a little help. Simple measures like loft insulation can improve your rating quickly, and replacing more than ten year old boilers is a great method of jumping a rating or two.

Where do you live?

The further south you live, the more sunshine you’ll receive. Solar panels are definitely more popular in the south of the UK, but the performance differences across the length of the UK aren’t astronomical.

How is your home connected to the grid?

Off grid solar pv systems are different to on-grid systems, as they require battery systems. We’re currently trialing them, but do not yet currently offer them as standard.

Choosing the right solar panels for your property

Our solar panels

We stock good quality solar panels from manufacturers that we know and trust. All of our decisions are made on technical data and customers influences and request – we’re completely unbiased.

EvoEnergy Solar Panel RangeWe look for efficiency, value, aesthetics and product warranty when selecting new products for our range.

More efficient panels produce more energy from a smaller roof space. If you have a smaller than average roof, you might consider a high efficiency panel to get the most out of your roof. Value panels are great for maximising your return on investment over the 20 year period, but more expensive panels will last much longer and will perform more consistently all year round.

We stock a range of all-black solar panels as well as more common blue modules, with both black and grey frames. Black solar panels are especially suited to slate roofs as they look less obvious alongside darker tiles. Solar tiles also come in a range of colours, which also work well with dark slate roofs.

Finally, warranty is important as many product warranties stretch into the 20+ year period. The product warranty will show you how long the manufacturer will back the panels for, and this is typically matched to a performance output, which will describe how the panels efficiency will degrade over time. All solar panels performance declines over time, but this will not be more than 10-15% over 20 years. SunPower, one of our most popular panels offer an 87% performance guarantee for 25 years.

Current solar panels (PV)

We currently stock a whole range of solar panels, but our most popular are Trina, Conergy and SunPower. We also stock the popular Panasonic, Suntech and Suntellite panels.

Trina solar panels

Trina are the fifth largest PV manufacturer worldwide and have a great value range product. Trina’s 240W panel is one of our most popular as it offers outstanding value for money. The panel is blue in colour, contained within an aluminium frame.

Conergy solar panels

Conergy provide every part necessary for a PV system to operate. We stock many of their products, and like their panels as they are a great mid-range offering. Conergy back their products with 12 year product warranties and 25 year performance warranties. The 255Wp Power Plus Noir edition is finished in an all-black frame and outperforms competitiors’ products in low light conditions.

Sunpower solar panels

Sunpower is a global leader in PV manufacture and design. The Sunpower E20 333W is the highest wattage MCS accredited solar panel in the UK. As such, they’re ideal for those wanting to maximise smaller roofs. SunPower recently announced new warranties on their solar panels. SunPower are now offering an 87% power output after 25 years, and a 25 year product warranty.

A little more about getting solar panels with EvoEnergy

We’ve installed solar on over 6,000 properties nationwide. We’ve been named Solar Installer of the year three times in the last four years and was the Renewable Energy Associations Installer of the Year 2011.

Solar PV is a great investment for the future – not only can you secure your energy bills, but the Governments feed-in tariff means that you can earn a great return on your investment of around 12 per cent.


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