Solar PV

How does Solar Power work?
The energy from the sun is collected by the panels we mount on the roof or ground and is converted into DC electricity (the type that comes out of a battery). The DC electricity is not useable as mains electricity and needs to be converted. That is the job of the inverter. The Inverter is the heart of the system and converts the DC electricity to mains electricity that can be fed into your property for you to use and/or be exported back to the grid. The inverter works totally automatically and does not require any attention in normal operation.

The power from the inverter feeds into the property on your side of the incoming meter, meaning that the energy it produces is used by your property first with only surplus being exported to the grid.

A PV system is largely a fit-and-forget system. The best modern inverter systems provide very detailed production analysis via internet portals or apps so any issues can be quickly spotted and dealt with. They can also optionally be set up to provide full site energy consumption analysis to give previously unheard of levels of information on site production and consumption. This data can then be used to help with future energy saving measures or help justify battery storage options.

Financial benefits

From 2020, domestic Solar PV has no direct government subsidies. The previous “feed-in-tariff” has ended.

In practice, most of the benefit from a new PV system comes from the savings on the electricity bill, in which every unit of electricity that is used in the property from the PV system saves the cost of buying that unit from the electricity supplier. In addition to this, when more energy is being generated than the property is using, it will be exported to the grid.

The government legislated for a new scheme called the “Smart Export Guarantee”. This scheme obliges larger energy suppliers to pay something for the exported energy they receive. The government did not specify an amount per kWh, leaving it to the market to settle a value. The amounts vary but seem to have settled around 4-15p per kWh of export. This is then typically applied as a credit against the normal incoming bill.

For a current list of energy supply companies that are offering SEG payments, please click this link to the OFGEM website https://www.ofgem.gov.uk/publications/seg-supplier-list

In order to claim the SEG payments, your installation will need to be fitted by an MCS certified installer, such as ourselves, and you will need to have a suitable active smart meter fitted by your energy supplier.

Typical 4-6kW domestic solar PV installations (WITHOUT battery storage from H2-eco cost around £8-10,000 including supply, installation, scaffold access and VAT (currently zero-rated for residential installations).  There are typically three constraints as to what can be fitted – your available budget, the amount of suitable roof space and the output that your local Grid Operator will allow you to connect. We would generally recommend going with as large a system as these limits will allow, even if generation is higher than you might currently use.

With regard to battery storage, we would typically recommend living with Solar PV for a year, through the generation “seasons” before making a decision about whether, and how much, battery storage might be suitable. See the Battery Storage page for more information about the solutions that we offer. These

To find out more about how you could benefit from Solar PV, plus to get a no-obligation quote, please get in touch. 

Mounting systems

PV panels can be mounted on pitched roofs, flat roofs and the ground. The most common is a Pitched roof.

There are 2 main installation types for pitched roofs, commonly known as “on-roof” and “in-roof”.

On-roof installations

On-roof installations use brackets that are carefully installed in conjunction with an existing or new roof covering of slates or tiles. MCS approved Brackets are available for almost all tile/slate types and when installed properly leave the roof just as weathertight and structurally sound as it was before the PV system was installed. Because the panels are installed above the roof covering with an air gap between, they are able to run with the benefit of air cooling.

PV panels are more efficient when cooler so this provides the most efficient method for mounting panels if output is the key consideration. On roof mounting typically allows more flexibility in panel layout where roof space is tight or a more complicated shape.

In-roof installations

In-roof installations using equipment from, for example, GSE replace the roof covering with the PV panels. This gives a neater, more integrated look which some people prefer. In-roof mounting components are more expensive than on-roof components so on a retrofit installation, an in-roof installation will cost more. On a new-build however, the fact that the area covered with panels will not need to be covered with tiles/slates will offset the additional cost.

The downside of in-roof systems is a small drop in production due to the panels running at slightly higher temperatures because they have less air movement than an on-roof system. Estimates vary between 3% and 5% less than on-roof. Due to the way the in-roof systems are fitted, they can sometimes limit the number of panels that can be fitted – especially on more complicated roofs with multiple pitches, areas, skylights and dormers etc.

Both system work well so it’s a client decision as to whether to prioritise performance (on-roof) or aesthetics (in-roof).

You will see many photos on our website of both in-roof and on-roof installations – both can look very neat

Solar Edge

Watch how SolarEdge’s power optimizers enable greater energy yield for the entire PV system.

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