How do solar panels work?

Solar Photovoltaic (PV) panels can be attached to roofs, walls or frames and are made up of photovoltaic cells. Each cell is made from one or two layers of semiconducting material, usually silicon. When light shines on the cell it creates an electric field across the layers. The stronger the sunshine, the more electricity is produced. The strength of a PV cell is measured in kilowatt peak (kWp). That is the amount of energy the cell generates in full sunlight.

However, the modules still work when it is cloudy, although when it is overcast they are less efficient. When it is slightly overcast, the panels may produce around half the power they would in sunny conditions. When the sky is heavily overcast, this could reduce further. Temperature is less important than the amount of light. In fact, clear cold days provide perfect conditions because PV modules operate better at cooler temperatures.

Even when covered in snow, panels can still function. If you imagine standing under a glass roof covered in snow, light can still get through. Reduction in efficiency is similar to cloudy conditions.

Should I install battery storage?

A solar panel installation generates electricity but is not capable of storing any energy which is not used immediately. A battery will store any excess electricity, so you can use the power that your panels generate at a time that suits you.

Before deciding to install a battery, it is important to work out how much of the energy generated by your panels you are using already. If you are at home during the day and using appliances, it is likely that you will be using a significant percentage of the output and will probably not benefit a great deal from battery storage.

However, if you are usually out at work during daylight hours, the electricity generated during this time could be stored for you to use when you return home in the evening and help reduce your electricity bills.

It is anticipated that the new Smart Energy Guarantee (SEG) will create a market for excess energy created by small scale renewable technology, where energy firms will compete with each other to offer the most attractive tariffs for electricity fed back into the National Grid.

Financial considerations aside, the attraction of battery storage for many is the prospect of being less dependent upon the National Grid (remember the 1970’s?) and, of course, the reduction in your carbon footprint.

What is the difference between the Smart Energy Guarantee (SEG) and the Feed-in-Tariff (FiT)?

Until the end of March 2019, small-scale generators of renewable energy, such as solar panel owners, benefited from the feed-in-tariff, which was designed to promote the uptake of small-scale renewable energy technology. As the cost of the technology reduced, the tariff was scaled down and eventually withdrawn in 2019. It was made up of two payment tariffs: the generation tariff, which paid a set amount for every unit of electricity generated, and the export tariff, which paid a set amount for every unit of electricity exported back to the grid. Because there was no reliable way of measuring the electricity exported, the amount was deemed to be 50% of the energy generated.

On 1st January 2020 the feed-in-tariff was replaced by the Smart Energy Guarantee (SEG), which obliges larger energy companies with over 150,000 customers to offer at least one tariff to smale-scale low-carbon generators (eg. solar panel owners) for any electricity they export to the grid, provided that the total installed capacity is 5MW or less, that the system was installed by a MCS certified installer and that there is an adequate export meter. (See HERE  for details).

SEG tariffs can be fixed rate or flexible. Currently, most energy companies are offering a fixed rate tariff which pays a set amount per kW hour of electricity, whatever time of day it is fed into the grid. Flexible rate tariffs, such as those offered by Octopus, pay a different rate depending on when the electricity is exported. So if you export electricity in the evening when there is high demand, you will receive a higher rate than if you export it during the afternoon. Batteries give the opportunity for the energy generated by your panels to be stored and released back to the grid at the most profitable time.

You are not eligible for the SEG if you already receive the FiT, unless you opt out of receiving the FiT export payment.

What is the Electric Vehicle Homecharge Scheme (EVHS)

In order to encourage the use of electric vehicles, OLEV (Office for Low Emission Vehicles) is offering a grant to offset some of the upfront costs of installing a charging point at home. It covers 75% (up to a maximum of £350) towards the cost of a chargepoint and its installation. You must have purchased your electric vehicles after 1 October 2016, have off-street parking and use an OLEV improved installer. (See HERE  for details). The vehicle owner must complete a customer declaration and the approved installer then claims the grant (the customer must not be charged for the grant in advance of payment being made by OLEV.)

The Workplace Charging Scheme (WCS) is a similar scheme aimed at businesses, charities and public sector organisations which provides a contribution of 75% of purchase and installation costs, up to a maximum of £350 for each socket, for up to 40 sockets.

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