How photovoltaics it work
In simple terms...
Electricity is produced from sunlight through a process called solar photovoltaics. Photovoltaic cells are made of semi-conducting materials, so when the sunlight strikes, it is converted into electricity.
The technical part...
The solar cells are made of several thin layers of silicon. When sunlight strikes, the electrons within the cell are knocked loose.
By the absorption of a photon (light particle), the negative electron gets shunted away from the silicon atom, and a positive ‘hole’ remains. The freed electron and the positive hole together are neutral. Therefore, to be able to generate electricity, the electron and the hole need to be separated from each other. This is done by giving layers within the cell opposite charges, so that the freed electrons cannot return to the positively charged holes. When the electrical contacts on the front and rear are connected through an external circuit, the freed electrons can only return to the positively charged holes by flowing through this circuit, thus causing electricity to flow. This means that the greater the intensity of light (larger number of photons), the greater the flow of electricity.
...and what happens if the sun isn't out?
Even if the sky is overcast, PV still produces electricity. This is because PV cells not only use direct sunlight, but also diffuse solar radiation, which is light that has been scattered by dust and water particles in the atmosphere. Obviously the amount of useful electricity generated is proportional to the intensity of light energy which falls into the conversion area. However, you can still have an electricity supply even without the sun!
To determine the PV electricity generation potential for a particular site, it is important to assess the average total solar energy received over the year.
What about at night?
Despite its advanced technical capabilities, a PV system will not generate electricity at night.
For further information please contact us
Frequently Asked Questions
Hopefully we can provide answers for your most frequently asked questions, please click on a question to see our answer.
- How does it work?
- Click here for an explanation of how photovaltaic panels work
- What is a feed-in tariff?
- Feed-In Tariffs (also known as FITs) are the electricity part of what some people call Clean Energy Cashback, a scheme that pays people for creating their own "green electricity". ref http://www.fitariffs.co.uk/FITs/
For further information please visit fitariffs.co.uk
- What is the payback time on the system?
- The payback time on a standard size array is typically between 8-10 years, depending on the system that you choose. ECI will provide you with a predicted payback time and total yield with your free no obligation quote.
- How much grant is available?
- The simple answer is, for most people in domestic and commercial premises - no, there are no grants available. Though if you are installing on behalf of a charity or for a local council, you may still be entitled to one.
- What are the savings?
- Give us a call on 08446 651 135 and we can talk them through for you, they vary quite widely depending on a number of factors like roof angle and the direction the building is facing.
- How can I see how much electricity I am saving?
- We will provide a kilo Watt hour meter, this will tell you how much you have produced. This is also the figure which will be used by your energy company to pay you.
- Do I need planning permission to install a roof mounted system
- In England and Scotland, you don't need planning permission for most home solar electricity systems, as long as they're below a certain size - but you should check with your local planning officer if your home is a listed building, or is in a conservation area or World Heritage Site. - energysavingtrust.org.uk
- How much maintenance does my system need?
- There is very little maintenance required; however, we would recommend that you have an annual check, to check for damage to the panels from falling debris and to inspect for damage to the cables caused by rodents.
- Can I claim the Feed In Tarriff if I install them myself
- No; all installers have to be Micro-generation Certification Scheme (MCS) registered in order to claim the fee-in-tariff. This helps to keep a high standard of solar panel installs.
- How long is my PV microgeneration system guaranteed for?
- Work carried out by ECI holds a 1 year guarantee. Depending on the brand; the panels are usually guaranteed to have minimum of 80% output after 20-25 years and the inverters usually come with a standard 5 year guarantee often with the option to upgrade to 20 years for a small fee.
- Do I need to alter my roof?
- Do I need to alter my roof - Internally we may put some supporting wood-work in your loft between the rafters, but the integrity of your roof should be unaffected.
- Does my solar array need to be south facing?
- A south facing roof is the optimum direction for your array to face, the system will be slightly less efficient the further it is from south. ECI can provide you with predicted performance of an array facing any direction.
- If I move house, can I take the PV array with me?
- You can take you array with you if you move; however when you re-install at your new property you will only receive the Feed-in-tariff at the point of installation, which is likely to be lower than the one you started on.
- Do PV systems make any noise?
- The inverter may make a small hum but its more than likely that you won't hear it. It is also worth bearing in mind that the system will be shut off at night when you house is likely to be at its quietest.
- Is my roof strong enough to support a roof mounted system?
- Your roof needs to be able to withstand the weight of the solar array. We can advise on viability from information you supply us, but if you are unsure, you will need to speak with a structural engineer.
- Do I need to insure my PV system?
- It is worth adding your array to your house insurance; with most insurers this can be added free of charge.
- Will my PV system supply all my hot water?
- No, a solar/PV system generates electricity, not hot water. If you are interested in using solar to generate hot water, you need a solar thermal system, we offer these as well.
- Do I expect to use all that I produce
- Yes you probably will; in fact the ideal would be that you use it all, as you will not only benefit from the feed-in-tariff, but also won't have to import power from the grid.
- Do you do other types of renewable energy installations
- Yes we offer solar hot water systems
- How big are the panels?
- We can supply panels in many different sizes to suit your installation and power requirements.
- How much does it cost?
- Costs for installing a solar electricity system vary a lot - an average system costs between £8000 and £14,000 depending on it's size and type.
- the more electricity the system can generate, the more it costs but the more it could save.
- solar tiles cost more than conventional panels
- panels built into a roof are more expensive than those that sit on top but, if you need major roof repairs, or you are building from scratch, PV tiles can offset the cost of roof tiles.
How a photovoltaic system fits into your homes electrical circuit
For further information please contact us
08446 651 135