How much power do we use in the home?
Everyone consumes energy, but sometimes it is hard to know just how much power is really being used in the home. Domestic electrical usage is measured in kilowatt hours (kWh) and the best way to understand what this means is to look at what a kWh does in everyday life.
A kWh of electricity can provide:
- 1200 electric shaves
- Drying your hair 15 times
- Listening to 15 CD’s
- Using a small refrigerator for 24 hours
- Microwaving 20 meals
- 4 evenings of light with 60W incandescent lamps
An average 3 bedroom house uses between 9-10 kWh per day (Source: Energy Savings Trust).
What is Solar PV?
Solar PV is a renewable energy system which uses photovoltaic modules on the roof of a building to convert light into electricity. Voltaic cells are made up of thin layers of semi-conducting material (usually crystalline silicon) which generate an electrical charge when exposed to direct light.
How does Solar PV work?
A Solar PV module is made up of mono-crystalline cells which consist of two or more thin layers of semi-conducting chemically treated silicon materials. The chemicals react when light hits the cell, creating an electric field across the layers, producing a direct current. The greater the light intensity, the greater the flow of electricity. This direct current (DC) is then fed into an inverter which changes it into a usable alternating current (AC).
Where did the idea of PV come from?
In 1839, a French scientist named Edmund Bacqueral discovered the photovoltaic principle and the first basic solar cell was developed some 40 years later.
However, today’s photovoltaic technologies were developed in the 1950’s and 1960’s for uses including satellites, spacecrafts, electronic watches and calculators. The idea behind the domestic use of PV to provide renewable power for the home, has now been established for over 20 years.
Where can I install my PV modules?
The location of the PV is vitally important. The modules must receive the maximum amount of day light possible, so it is not advised to install the modules in situation where surrounding buildings or trees may cast shadows. The best location for a PV solar module is on a south-facing roof. Various mounting arrangements including on-roof, in-roof and flat roof kits, both landscape and portrait.
What's the difference between solar thermal and PV?
As previously mentioned, Solar Panel PV systems use energy from the sun to generate electricity with roof mounted modules.
Solar Thermal employs roof mounted collectors to absorb energy from the sun. These collectors are usually connected to the lower coil of a twin-coil cylinder via a sealed circuit containing a special glycol/water solution. The pump in the system circulates the heated fluid from the collector to the cylinder, where the stored water is heated for use in the home.
What happens when the weather is cloudy or cold?
Solar PV Panels use light to generate electricity, so 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 as much as half the power they would in sunny conditions. When the sky is heavily overcast, this could reduce further. Temperature is less important than how much light there is. What’s more, a clear cold day is perfect, because PV modules operate better at cooler temperatures.
What happens if the modules get dirty?
Solar PV modules are self cleaning when mounted at an angle of at least 15ยบ. The amount of dirt on the modules depends on their location. If the modules are in a heavily silted area (e.g. under trees) the build up of dirt may reduce the power the panel generates by around 10%.
What is the expected lifespan of Solar PV?
Solar PV modules should be expected to last at least 25 years, since there are no moving parts. The modules have a twenty-five year performance guarantee.
Can I sell the electricity I produce back to the energy supplier?
Most electricity suppliers will pay for power fed into the Grid (feed-in) from domestic Solar PV systems. The easiest way to do this is by signing up to a ‘Buy Back’ or ‘Feed-in Tariff’ scheme with your power supplier. There are two main types of tariff available:
- Generation: You are paid for all of the electricity that your solar PV system generates even if you consume it in your home.
- Export: You are paid for just the electricity that is exported back to the Grid and not for any electricity you have consumed.
What are Feed-in Tariffs (FiT)?
On 1st February 2010, the Government announced new standard generation Feed-in Tariffs (FiT) rates due to start on 1st April 2010, which are guaranteed for 25 years. This new payback scheme, results in a shorter payback for Solar PV systems, making them an extremely attractive green option for any home. PV systems registering with the scheme between 1st April 2010 and 31st March 2012 will benefit from the following:
- Any system less than 4kW on a new build = 21p per kW pay-back.
- Any system less than 4kW on a retrofit = 21p per kW pay-back.
- Any system 4-10kW new build or retrofit = 16.8p per kW pay-back.
- Any system 10-100kW new build or retrofit = 16.8p per kW pay-back.
This means that if you normally pay 12p per kWh for your electricity, you would effectively get both the power consumed for free and the FiT. So on a retrofit system below 4kW this would mean 12p + 41.3p = 53.3p per kWh saving!
Any Solar PV system installed after the 15th July 2009 is eligible for this Feed-in Tariff at the above rate, provided the system uses MCS approved equipment and has been fitted by an MCS accredited installer.
What is the difference between polycrystalline and monocrystalline modules?
The polycrystalline modules use cells made from a multicrystalline silicon material with a blue marbled appearance. The monocrystalline modules have cells of a darker appearance, almost black in colour. These are produced from a pure single crystal silicon, resulting in a cell which is slightly higher in efficiency than the multicrystalline silicon cell. Thus the monocrystalline modules are typically smaller in physical size than a polycrystalline one of the same output.
What mounting options are available for DIS Contractors Solar PV?
There are several different mounting arrangements available including on-roof and flat-roof (by special order), with both landscape and portrait module installations possible.
How ‘Green’ is DIS Contractors Solar PV?
D I S Contractors solar PV is a renewable energy source that does not require the burning of fossil fuels to generate electricity and does not leave a carbon footprint as it creates no carbon dioxide during operation. For each kWh of electrical energy generated using a fossil fuel, about 1.5lb (0.68kg) of CO2 is released into the atmosphere and the average person uses around 600-800 kWh of energy every month.
D I S Contractors Solar PV makes no noise, emits no pollutants, creates no waste and uses no fuel, meaning it is a VERY green energy supply.
How long is a Solar PV System guaranteed for ?
All D I S Contractors Solar systems are covered by a unique five year manufacturer’s guarantee, subject to the system and its components e.g inverter, modules, etc being supplied by D I S Contractors as a kit. Please note that D I S Contractors do not warranty mixed systems i.e. those which include an inverter or modules that have not been supplied by D I S Contractors. For further information, please contact the D I S Contractors Customer Service Department. Tel 01522 825825
D I S Contractors Solar PV modules also carry up to a 25 year performance guarantee as follows:
- Performance guarantee to 90% output minimum after 12 years.
- Performance guarantee to 80% output minimum after 25 years.
