PHOTOVOLTAICS CONTRACTOR INSTALLED
CASE STUDY PV01
LEAMINGTON SPA
INSTALLED:
17 May 2006
FUEL REPLACED
Electricity from grid
DESIGNED TO SERVE
2 adults
PROPORTION OF NEEDS MET
33% of imported power
PROJECT IDEA
What I did:
Installed a Solar PV array on roof of my house
Why I carried out the project:
To take a step towards reducing our use of fossil fuels, by reducing our consumption of imported electricity. To save money on electricity bills, and to get energy for free!
What type of equipment was installed?
• Kyocera Solar PV array
• KC125G-2 panels
• 3 kW peak generating capacity
Who was the installation company?
Installation was by Green Earth Energy of Pontrilas, Hereford. http://www.greenearthenergy.co.uk/
What costs were involved?
Total cost was £16,777, and I received refund (grant) from Energy Savings Trust of £7,500, leaving a net cost to me of £9,200. Net cost came out at £3,067 per kW installed
DID I THINK IN TERMS OF PAYBACK?
I knew the payback would be a long time, and it was not going to justify the installation on its own.
I expect payback to be around 25 years (depending how much energy prices increase)
FINANCIALLY WAS DECISION DIFFICULT?
The decision was not too difficult to make
WAS THIS SOMETHING I OR MY FAMILY DID NOT PURCHASE AS A RESULT?
We did not have to sacrifice any other expenditure - we had separate savings for this project
WAS THERE AGREEMENT IN THE HOUSEHOLD THAT THIS WAS THE RIGHT THING TO DO?!
Yes, my wife and I were in full agreement that this is the right thing to do
WHAT I LEARNT FROM THE PROJECT
• Not all energy suppliers are equal when it comes to payments for exported electricity!
• Powergen were very disappointing due to the tariff, and npower have been much, much better.
WHAT WORKED?
The whole installation has worked perfectly - no issues at all
WHAT DIDN’T WORK?
Nothing
UNEXPECTED KNOCK ON EFFECTS
• It made us even more aware of our energy usage - we thought we were already good at turning things off, but this helped push us on further.
• Devices that used to be left on standby because they were too difficult to turn off easily, now get switched off, even if it's a little awkward.
• Devices that we previously didn't consider (the CD player in the Dining Room) which shows the time, is now left switched off, unless we use the room - we can live without the clock function!
• It also helped us to agree to turn off radiators in rooms not used frequently, and to close the door so that the corridor doesn't try to warm that room.
HOW WERE CARBON EMISSIONS AND PREVIOUS FUEL CONSUMPTION REDUCED?
Energy imported from electricity company has been reduced by about 40%
WOULD I REPEAT THE EXERCISE?
Yes
WHAT WOULD I DO DIFFERENTLY?
Include a remote display for Inverter - that shows the same data available from on the Inverter - Watts, Volts, Current and Maximum. It costs around a hundred pounds, and when the Inverter is tucked away in the loft, it would make it easy to check on performance.
DO I PLAN TO INSTALL OTHER RENEWABLE ENERGY EQUIPMENT?
Yes, Solar Hot Water
ANY OTHER INFORMATION?
• I have a small web site with pictures and further details (homepage.ntlworld.com/scooby52 )
• I update it with performance results, and savings, and welcome questions. I will 'earn' further income from the exported energy as I will be paid for ROC's (Renewal Obligation Certificates) by my energy company.
• I expect my first payment in 2008, and anticipate around £120, depending on the value of ROC's at the time.
Additional notes taken in discussion with Ian Davies - 2nd March
It was difficult getting companies to come to the house. One did come and happened to offer the best price. The contractor persuaded ID to go for a larger array, 3kW instead of 2kW on the basis it would cost relatively little extra because of the ‘overheads’ involved in fitting just 2kW.
ID believes it will take 20-25 years to recoup costs after taking into account the grant.
The system includes an inverter which is fitted in the loft. Cables can run outside the property. An inverter converts DC (the direct current produced by the panels) to AC (the alternating current that is used in the distribution network including our homes and businesses) – and is also used to smooth out the electricity voltage produced by the panels. It was required in this case to have a separate fuse box which the contractor fitted.
In this case the inverter is approx’ 2’ x 1’ x 1’ in size. It makes some low level noise. A ‘check meter’ is provided with the installation – which shows the amount of electricity generated and this figure is used to monitor performance and in some cases to provide to the power company who takes exported electricity.
To get the grant under the Low Carbon Buildings Programme it is required that an accredited contractor is used for the installation, and that the installation is connected to the local distribution network so any surplus can be exported.
An ‘export’ meter is required so that surplus power can be ‘exported’ to the local distribution network / grid. This is called a ‘grid connected’ supply. Modern ordinary meters are designed not to run backwards
The export meter costs around £100 yr to provide / maintain. Therefore the system needs to export more than £100 worth of electricity a year. In the past power companies had a standing charge to cover this cost of import meters. The cost now tends to be included within the unit cost of electricity – although it is now included in a higher cost per unit for the first 250 units (or there abouts depending on your supplier).
Thus
• many people (tending to have small systems) do not have an export meter
• most companies will estimate what you use and therefore they are likely to underpay
For small generators power companies tend to estimate annual generation.
Powergen charge and pay the same rate per unit of electricity for import or export of electricity. However they would not say to ID how they would estimate the amount generated until after the contract was signed.
Powergen’s estimate of electricity generated was based on: ~
• number + size of panels and which way they face, and the
• average annual electricity consumption used in a house of the size involved (based on number of bedrooms)
ID was making just £20 / yr ‘profit’ on this basis.
Npower (to which ID changed) assume that you export 50% of what generate. They also charge and pay the same rate for import and export of electricity. They also require the generator to let them have the generation figures from the check meter.
ROC’s (Renewable Obligation Certificates) are available as a government subsidy on the generation of electricity from renewable sources. It is available on every complete MWhr (megawatt hour) / 1,000 kWhr (kilowatt hours) that is generated in each year of generation. At present this is worth £44 per ROC.