Solar panels are made up of one or two layers of semi-conducting material, usually silicon, in “cells”. When they are exposed to light the cells releases a small amount of electricity. By combining several cells into a “panel” and a number of panels into an “array” enough electricity is generated to either power your home or business, or sold to your energy provider.

Solar PV panels need direct sunlight to generate electricity so a southerly aspect is ideal. Arrays facing to the east and west will also generate electricity for the times of day that they face the path of the sun.

For similar reasons an array should be positioned so that no overhanging structures or vegetation shade the panels.

No, solar PV panels come in a variety of forms.

There are two main types of solar cells that differ in the arrangement and number of silicon crystals. Polycrystalline panels are made from wafers created by cutting thin strips from a solid block of silicon. These are relatively cheap to manufacture and historically have had lower efficiencies than other panel types however technology has improved to increase it so the difference is much less significant. Polycrystalline panels usually have a blueish tint.

Monocrystalline cells are usually black and have a single silicon crystal. They are efficient and perform better in low light conditions than polycrystalline panels.

There are a myriad different options in terms of frame and backing sheet colour, efficiencies and panel dimensions.  Panel outputs have increased over time as the technology has improved.

A complete solar PV system will usually comprise several solar panels to form an array, an inverter to convert the DC electricity generated by the panels into usable AC electricity and a generation meter to tell you how much electricity the system has created.

Inverters come in a variety of forms depending on the size of the installation and where the array is located.

• A “string” inverter will convert the energy from multiple solar PV panels which are connected in line. The disadvantage of a string inverter is that if a single panel is partially shaded it will restrict the amount of electricity the entire array will produce.
• An alternative to a string inverter is to opt for a system using “micro-inverters”. These are just small inverters with a separate one for each panel in the array. This allows each panel in an array to generate independently of the other panels making them ideal for situations where there may be partial shading.
• “Solar optimisers” work in a similar way to micro inverters in that one is required for each panel, however these control the flow of the DC current from each panel to a single inverter that acts for all the panels in the array. As with micro-inverters, they offer higher system efficacies than by means of a string inverter and are ideal for use where shading of the array could be an issue. An additional benefit of solar optimisers is that they can provide real-time performance monitoring of every panel in an array.
• Hybrid inverters will also charge a battery system and are a useful options if a battery might be added later.

Solar PV panels come with two warranties, a Performance Warranty and a Product Warranty.

The Performance Warranty will guarantee the maximum drop in efficiency of the panel over a 20 or 25 year period. Commonly this is stated as a percentage figure that the panel is guaranteed to produce at given points in the lifetime of the panel. Most quality panels will provide a guarantee that the performance will not drop below 80% of its original efficiency at the end of the given period.

Although the life expectancy of a solar PV panel is to be expected to be more than 20 years, product warranties for the physical construction of a PV module are generally for 10 to 12 years.

The efficiency of string inverters reduces over time and have a life span of 10 to 15 years. This is shorter than that of the panels, so will be necessary to replace a string inverter to maintain the overall output of an array.

Micro-inverters and optimisers have a longer life expectancy as the electrical load passing through them is less than for a string inverter.

Yes, all the electricity you generate is free and can be used to run your household appliances from lights to the dishwasher, a hairdryer to a heat pump! A typical 4kW domestic array with a southerly unshaded aspect in the north of England will generate around 3,500kWh of free electricity every year. The average UK home consumes around 4,000 to 4,500kWh of electricity so a PV array can make a significant contribution towards this.

It of course must be remembered that peak times for electricity consumption are the evening and winter months when the sun is not shining and the panels may not be generating as much electricity.

Any electricity you do not use can be sold back to your chosen electricity company through the Smart Export Guarantee though this will not be as financially beneficial as if you use your self-generated free electricity. Small changes in routine such as using the dishwasher during the day rather than overnight will maximise the benefit of installing a solar PV system.

With rising electricity prices, the simplest way of maximising your return is to use as much of your self-generated electricity as you can. Small changes in routine such as running the dishwasher during the day rather than overnight will help achieve this.

The falling cost of batteries and rising electricity prices have made battery storage a viable proposition in order to store excess electricity for later use rather than export it to the grid.  Please see our battery storage page for more information.

A simple and cost effective option is to add a “solar switch” to your solar PV system which will divert any self-generated electricity from your solar PV array to an immersion heater in your hot water tank. For a typical household, this will provide all domestic hot water from the middle of Spring to the middle of Autumn making a saving of around £100 against the cost of heating by a gas boiler.

Fervo will be pleased to advise you on how best to maximise your returns.

For businesses using large amounts of electricity solar PV can make a significant reduction to running costs as well as reducing carbon emissions. With options for mounting panels on all types of structures or mounting on land there are few instances where a solar PV array will not be of benefit.

In most domestic situations for roof mounted solar PV no planning consent is needed as it falls under Permitted Development rights. This is not the case for listed buildings or properties forming part of a scheduled monument. For properties in Conservation Areas or part of a World Heritage sites panels should not be installed to the highway frontage.

Planning permission is required for any ground mounted array except for small arrays (9m²) within the curtilage of a domestic property and 5m from a public highway.

Planning consent may be required for solar PV installations to commercial properties.

Fervo undertake a detailed assessment of the location where a proposed array is to be installed noting alignment, aspect and any issues of shading that could impinge on the performance of an array. Using historic weather data, a calculation is prepared that will estimate how much electricity the array will produce over 12 months. A Performance Estimate will be provided detailing all of this and what financial benefits will arise from your proposed installation through the Feed in Tariff scheme.

The simple answer is no, providing space is not a problem, but there are other considerations;

• To install a solar PV array with an output over 3.68kW consent is required from the District Network Operator (DNO) who manage the local electricity infrastructure.
• You should consider how much of the self-generated electricity you will use and how much is likely to be exported. Unless you will use most of the electricity, the financial return may not be attractive. Fervo will discuss this with you and prepare a Performance Estimate outlining the likely financial benefits your proposed solar PV array will provide.