How do solar PV panels work?
A solar PV system captures the sun’s energy and uses it to generate electricity. The system will continue to work even in cloudy conditions. Not only could you save money by generating your own electricity, you could also earn money from the Government's Feed-In Tariff.
Technical information made simple
Solar PV panels are made up of solar cells. Each cell is made from one or two layers of semi-conducting material, typically silicon, covered by non-reflective glass. Here’s how a typical system works:
- The light shines on the cell and this creates an electric field across the layers, causing electricity to flow.
- The electricity flows through a cable and is collected at a central point generally under the panels and located in your roof space.
- The electricity produced is Direct Current (DC) and needs to be converted to Alternate Current (AC) by an inverter which is fitted as part of the system. This is AC current is then used in your home to power your lights and appliances.
- If you don’t use all the electricity that you have generated, it will be fed into the National Grid automatically. It is estimated that you will export 50-75% of the electricity you generate. If the system can’t provide you with enough electricity, i.e. at night, the Grid will automatically supply you as it does now, for which you will be charged.
The stronger the sunshine, the more electricity you can produce, but PV cells don’t need direct sunlight to work – you can still generate some electricity on a cloudy day.
The strength of a PV cell is measured in kilowatt peak (kWp). That’s the amount of energy the cell generates in full sunlight. This rating will determine the amount of electricity that you can produce. Typical domestic units are 3 or 4 kWp.
- What is the payback for a solar PV installation?
- Currently a solar PV system should pay for itself in about 7-12 years, after which you'll continue to save money on your bills and receive FIT payments for the rest of the system's 25 year lifetime. If you complete out energy assessment you will be able to get a more tailored estimate for the payback to your own home.
- Are solar PV systems a lot cheaper now?
- The cost of the PV cells and associated equipment is driven by international supply and demand. Prices of these components have fallen substantially over the past few years as larger manufacturing facilities have been set up in response to strong demand particularly in Germany and Japan. Installation prices have in turn fallen as a result of the reduction in system prices and as the industry has grown. This drop in prices is set to continue.
- What guarantees do solar PV panels come with?
- It does vary from manufacturer to manufacturer but typically Solar PV panels will come with an output guarantee in the region of 20 and 25 years. The Inverter will have a shorter life, and your should budget to have this replaced once during the life of your system (25 years or more) and therefore has a shorter guarantee, typically around 5 years. The labour guarantee will depend on your installer and your should ask or study the fine print in your quote; 5 years is fairly typical.
- Will solar PV panels affect my home's rateable value?
- Council tax is based on the 1991 values and the government shelved plans to revalue all houses a few years ago, so currently, no. It is likely that there will be a revaluation in the not so distant future. When they do, the value of the solar panels will be included in the valuation, but the rating could also account for your home's the Energy Performance Certificate (EPC) which should reduce tax as you would have a lower EPC score.
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