Photovoltaic Panels
Solar photovoltaic panels capture the energy from daylight and convert it into electricity and similar to the solar hot water panels are generally roof mounted on a south facing roof at between 30 and 45 degrees. All photovoltaic panels are made up of silicon cells. When sunlight hits these cells electrons are separated from their atoms thus creating voltage and hence electricity. A typical 1.3 square meter panel will have 48 cells connected together and will have a power output of between 160 and 200 watts.
A complete system is then built up from varying numbers of panels depending upon the output required. For example here at the warehouse we have nine 170 watt panels on our roof producing electricity for use in the warehouse. The system has a kWp of 1.53 and, using SAP, we would expect the system to produce, over a year, approx 1275 kWh. In reality, over the last year, the system produced 1521 kWh, which is 20% better than we expected. To estimate the amount of kilowatt hours that will be produced in a year from a system you multiply the kWp figure by 83% (an approximate guide).
reading of the output
Like wind turbines you need to either use the electricity produced, store it or export it to the grid. Feed-in-tariffs: Introduced on the 1st April 2010 to promote the installation of microgeneration systems such as photovoltaic panels and wind turbines. With pv the rates are variable depending upon the size of installation and whether they are being retrofitted to an existing house or being fitted during construction of a new build property. The rates start at 21p/kWh for a domestic scale system (≤4kWp) with a 3.1 p/kWh additional payment on exported electricity. The tariff is geared toward production, which is good news, as it means that you will be paid on the electricity that you produce and use yourself.
An example: You install a 3.92 kWp system consisting of sixteen 245 watt panels. Using SAP, we would estimate that this system will produce 3365 kWh in a year (south facing). You will receive 21 p/kWh on all of the 3365 kWh production and an extra 3.1 p/kWh on assumed exported electricity, this is deeemd to be 50% of the total production. So you will recieve £707 (21p x 3365) plus £25 (3.1p x 50% of 3365) which is a total tariff value of £759. Add on the saving of not buying 50% of 3365 at 14.5p/kWh (assumed) which is £244, giving a total yield £1003. A 4 kWp system would cost in the region of £9000 inc vat so this gives a yield of 11.2% ROI p.a.
Costs: A typical installation of a 3 kWp system would cost £7650 and a 4 kWp system would cost £9000. As you can see the bigger the system the lower the cost per kWp is. Costs will vary from installation to installation depending upon factors such as ease of access to the roof, type of roof tile, length of cable runs, type of panel and size and make of inverter. Like most renewable energy installations VAT is charged at 5%.
We are completely independent and so will choose the panel and inverter to suit your needs. We use a range of panels from a variety of manufacturers such as Sharp, Sanyo, Schuco, Powerglaz, Ahead Renewable Technology and Sungrid. With the inverters we also use a range of makes including Fronius, SMA SunnyBoy, Diehl, Enecsys and Enasolar.
If you are interested in seeing if your house or office is suitable for a p.v. system please contact us.