for a brighter future tomorrow
Solar PhotoVoltaic (PV) Systems
Frequently Asked Questions
Based on many years experience we have compiled a very comprehensive list of questions that we often get asked. If you cannot find an answer to your question please don't hesitate to contact us by phone or email.
Q. How much space on my roof do I need for a solar PV installation?
Our grid connected systems start from around 1kW peak power, this occupies about 8m2 on your roof.
Q. How much electricity does a PV system output?
For every kW peak power installed on a South facing roof the system will generate around 800 kWh. This reduces by around 20% for an East or West facing roof.
Q. How much does a Solar PV system cost?
Installed prices (including VAT) start from around £4500 – £6000 (inc VAT)per kW peak power. This does not include any grants.
After a grant systems start from £2500 per kW peak power installed (inc VAT).
Q. Do I need planning permission?
Our roof mounted systems do not need planning permission unless the property is listed or in a conservation area.
Q. Do I need to inform building control that I intend to install a solar system?
Yes, you should speak to building control about your intentions, and they will advise you if you need to take any further action with them. Be wary of any installer who advisers you not to contact building control.
Q. Will my roof be strong enough?
Most roofs are strong enough to take a solar installation without any reinforcement.
Q. Do I need to inform my electricity supplier?
For systems below 16 Amps output (approx 4kW peak power) we will inform them once the installation is complete. For systems larger than 16 Amps we will require permission in advance from the network operator.
Q. What is the payback for a solar PV installation?
We would expect a system to pay for itself about 5-6 times over 25 years of use. This is based on an annual fuel inflation of 12.9%, calculated by Ernst and Young and the governments new feed in tariff proposals.
Q. Can I export any of the electricity I generate?
Yes, all unused electricity will automatically be exported, your electricity company will normally fit an export meter or they sometimes authorise us to fit it.
Q. How much will I be paid for electricity I generate?
This varies massively from different suppliers. ‘Good Energy’ currently pay 16p per kWh for everything you generate even if you use it your self (therefore you benefit twice). Scottish and Southern Electricity will pay 28p per kWh for everything you export. Contact the supplier for further details. The Government plans to review feed in tariffs and legislate in April 2010 and it has been proposed they will pay 36.5p per kWh for everything generated. See government press release for further details.
Q. What is a kWh?
A kWh (pronounced ‘kilo watt hour’) is a specific amount of electricity. 1 Kwh is identical to 1 unit of electricity that is shown on your electricity bill. An electrical item having a rating of 1kW will consume 1kWh for every hour it is on at full power.
Q. What is a Renewable Obligation Certificate (ROC)?
The government created an obligation for electricity suppliers to generate electricity from renewable sources. You will receive an ROC from Ofgem for every 1000kWh that you generate from your PV system.
Q. What does the inverter do?
The PV panels generate direct current (DC), this is not directly compatible with the 240V alternating current (AC) that is used in your property. The inverter converts the DC power to AC power that can be used in your property.
Q. How does the electricity I generate get in to my wall sockets?
We connect the system to your fuse board (consumer unit). The electricity will automatically flow from there to wherever it is needed.
Q. Do I need permission from building control to install solar panels?
Building control have some specific criteria in determining whether your need to submit a buildings notice. We will discuss this with them and you on a case by case basis. Often a buildings notice is not required.
Q. Are solar PV tiles available?
Yes, PV tiles are aesthetically very pleasing and are becoming more popular, the installation cost will be higher than large ‘on-roof’ panels.
Q. Will I have electricity during mains power cuts?
For the safety of electrical workmen our standard systems do not operate during power cuts. We can offer an upgrade that enables the system to automatically disconnect your property from the grid and to provide power from the panels and a battery back up in your property during power cuts.
Q. Do I need a three phase electricity supply?
Systems up to about 10kW peak power can be accommodated on a single phase electricity supply. More than this will require 3 phases with the power split equally between them.
Q. Does your prices include for Scaffolding?
Surprisingly, many PV installers do not include for installing the necessary scaffold at your property. We include for scaffolding installation in all our prices unless there are specific reasons for us not to.
Q. Are there any grants available?
The low carbon buildings program offers up to £2500 for solar PV installations. Further significant grants may be available from your local council, please contact them for details.
Q. Are the grants difficult to get?
No, difficultly obtaining grants is a rumour spread by unapproved installers. The low carbon buildings program grant can be applied for on line and will usually give you an instant response. Once the work is complete they aim to send you the money within 3 weeks.
Q. What is the difference between monocrystalline and polycrystalline PV panels?
Monocrystalline panels tend to be slightly more expensive than polycrystalline panels, however monocrystalline panels are regarded as having a higher output per kW peak power installed. Polycrystalline wafer has a dark blue colour, monocrystalline wafer is black.
Q. Will PV systems be dropping in price dramatically over the next few years?
Many developments are taking place in the PV industry and popularity is increasing. However, we would expect prices and performance to change gradually rather than a dramatic change. We would also expect grants to reduce as the installed base increases.
Q. Is efficiency important with solar panels?
Usually not, the efficiency of a panel relates to how effectively it can convert the sun’s light. Given that the sun’s light is free a panel can simply be made larger to offset a lower efficiency. Only when suitable roof area is at a premium does it make sense to choose high efficiency panels, this will maximise the amount of power that can be generated from a roof.
Q. Whose panels do you use?
Typically we use high quality UK and Japanese manufactured panels from Sharp and Sanyo.
Q. What guarantees will I receive?
Panels have an output guarantee of between 20 and 25 years depending on manufacturer. Inverters normally have a guarantee of 5 years. Most other components and labour is guaranteed for 2 years.
Q. Are your panels approved?
We only use the very highest quality of materials. The panels we use meet all the required standards including TUV and MCS approval for government grants.
Q. Will an electrician fit the panels to the roof?
No, all roof work will be completed by our trained roofing specialists. Many companies use the wrong trades people to fit panels on roofs, we use our electrician for electrical work and our roofers for roofing work.
Q. How are the panels fixed to the roof?
We use rigid steel brackets that are fixed directly to your roof rafters. The brackets hook out from underneath your existing tiles. We do not drill tiles/slates or use mastic/silicone to weather proof your roof. These techniques do not have a long life span.
Q. How long will the installation take?
Installation normally takes 2-3 days.
Q. How much do the solar PV panels weigh?
Normally about 13kg per m2.
Q. Are the solar PV panels fragile?
Solar PV panels are very robust and can withstand the normal stresses subjected by nature.
Q. Can I heat water with solar PV panels?
Once the panels have created electricity you could connect this to an immersion heater to heat water. However, electricity is a very flexible form of energy and in most circumstances would be wasted being used to simply heat water. We would advise that home owners should heat water with solar thermal (water heating) panels.
Please note that these answers are designed to be appropriate for typical installations. The exact specification for your system will be detailed in your personal proposal.