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A List of Frequently Asked Questions

Based on many years experience we have compiled a very comprehensive list of questions and benefits of solar panels in homes that many of our customers frequently ask. If you cannot find an answer to your question please don’t hesitate to contact us by phone or email.

How much power does a PV system output?


How much does a PV system cost?

£4,000 – £13,000

Will I be eligible for the FIT?

Carbon Legacy are approved MCS installers so our installations are eligible for all government incentives andachievee a D rating on your house EPC.

Do I need planning permission?

Our roof mounted systems do not need planning permission unless the property is listed or in a conservation area.

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.

Will my roof be strong enough?

Most roofs are strong enough to take a solar installation without any reinforcement.

Do I need to inform my electricity supplier?

For systems below 16 Amps output (approx 3.7kW 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. For systems 4kw and bigger. we will arrange this permission.

What is the payback for a solar PV installation?

We would expect a 4kW system to pay for itself within 10 years. This is based on an annual fuel inflation of 6%, calculated by Ernst and Young and the governments current feed in tariff rates. With the new FIT- Initial return on investment is around 5-6%% with some of our customers achieving as much as 12%- tax free if they have high base loads.

Can I export any of the electricity I generate?

Yes, all unused electricity will automatically be exported, your electricity company can fit an export meter or they can pay you based on estimated export rates (usually 50%). Sometimes the electricity supplier can authorise us to fit the export meter. Please do not confuse the export meter with the gross generation meter which we fit as standard on all our installations.

How much will I be paid for electricity I generate?

The Feed in Tariff currently pays 4.32p to 4.53p depending on the size of your system. See OFGEMS web site or ask us for the current rates.(FIT paid for all the electricity generated even if used in your own property).

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.

What is a Renewable Obligation Certificate (ROC)?

The government created an obligation for electricity suppliers to generate electricity from renewable sources. This system has now been replaced with the Feed in Tariff (FiT).

What does the inverter do?

The solar electricity 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.

How does the electricity I generate get into 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.

Do I need permission from building control to install solar panels?

A buildings notice is generally not required as we are approved installers and registered as ‘competent people’. However, different building control offices deal with these products differently so we would recommend that you confirm this with your local office.

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.

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. If you would like to know more about this feature, please visit our Nedap Powerrouter Page

Do I need a three phase electricity supply?

Systems up to about 10kW peak power can often be accommodated on a single phase electricity supply, however we do need to seek permission from your Distribution Network Operator (DNO). More than this will require 3 phases with the power split equally between them.

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.

Are there any grants available?

The Feed in Tariff is treated as a Public subsidy. If you receive any other Public grants then it will reduce your FIT. Private donations/funding do not affect the FIT.

What is the difference between monocrystalline and polycrystalline PV panels?

Monocrystalline solar electricity 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.

Will the price of PV come down dramatically in the next few years?

Many developments are taking place in the PV industry and popularity is increasing as shown by the 900,000 UK PV installations. However, we would expect prices and performance to change gradually rather than dramatically. The government is interested in maintaining a consistent return on investment for systems installed now and over the coming years. On this basis we would expect government incentives to reduce as the cost/performance ratio improves.

Is efficiency important with solar panels?

Often 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. Carbon Legacy can offer high and standard efficiency modules. The highest current efficiency panel manufacturer is SunPower of the U.S.A – they have a stunning range of aesthetically pleasing panels on the market which Carbon Legacy is an Authorised Partner and installer.

Whose panels do you use?

A list of our solar p.v suppliers can be found within the Solar PV Range Tab in the navigation menu – but we only use German and American panels. We have tried and tested other manufacturers which many other energy installers use, but have found most of, if not all Chinese solar panels are inferior to the precision and quality of German made SolarWorld and American made SunPower.

What guarantees will I receive?

Panels generally 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 usually guaranteed for 5 years. Check your quotation for specific details.

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 incentives.

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. This system allows two individual assessments on completed jobs by independent specialists in their field.

How are the panels fixed to the roof?

For standard roofs we use rigid aluminium or stainless steel brackets that are fixed directly to your roof rafters or roof lathes. The brackets hook out from underneath your existing tiles. For slate roofs we use a MCS approved Roof Limpet system and metal roofs use a short rail screw mounted systems. All come with 10 or 20 year warranties.

How long will the installation take?

Installation normally takes 1 full working day, but this could extend up to 3-4 days depending on size of installation and weather conditions.

How much do the solar PV panels weigh?

Our suppliers panels range from anywhere between 13-16Kgs per square meter.

Are the solar PV panels fragile?

Solar PV panels are very robust and can withstand the normal stresses subjected by nature – including up to 50mm-55mm hail stones impacting at 60mph.

Can I heat water with solar PV panels?

Once the panels have created electricity you can send this to an immersion heater to heat water. Where you are not using batteries to store and use surplus day time electricity generation in the evening then we can fit intelligent immersion controllers such as a Solar Cache. This will proportionally divert as much or as little surplus power is available until your hot water tank is up to temperature ready for you to use later.