Frequently Asked Questions


Solar PV General

1. What are photovoltaics (PV)?

2. How do we get electricity from the sun?

3. Do solar panels work without direct sun?

4. How much carbon can I expect to offset through installing a solar PV system?

5. What is a kWh?

6. What is the difference between Power and Energy?

7. What does MPAN mean?



Legal & Commercial

8. I understand that REI and the participating School/Business/Organisation (YOU) enter into a Power Purchase Agreement (PPA); how does this work?

9. Who owns the solar PV system?

10. There is a mortgage or other charge on the property. Do I have to tell the bank and will they approve the installation?

11. I am a Commercial landlord and I have tenants in my building. Can I still take advantage of the REI Fully Funded Energy Scheme?

12. What happens if we move or sell our property?

13. What if we want to extend or develop our building?

14. I am a Commercial landlord. Do I, or my tenant, benefit from the discounted electricity?

15. What happens if we don’t use all the electricity the solar PV system generates?

16. How will this system affect my insurance costs and cover?

17. What happens if we need to repair our roof during the term of the lease?

18. What if we want to buy the PV system from you during the term of the lease and receive the Feed-in Tariff ourselves?

19. What if we have a fire, natural disaster or the system is vandalised?

20. How can I be sure that we will be charged accurately for the solar electricity we use?

21. What is the cost of electricity produced by the system and does it increase?

22. Do I need to change electricity supplier



Installation & Technical

23. Does my building need to meet a certain energy efficiency requirement?

24. Is my roof strong enough for solar panels?

25. Will our roof leak?

26. What happens if the system breaks down or develops a fault?

27. How much maintenance do solar panels need?

28. Why should we trust your Company to be able to offer this solution, for 25 years?

29. Can you fix solar PV panels to any roof?

30. Do I need planning permission?

31. Do I need to inform Building Control about the installation of a solar PV system?

32. Are solar PV systems noisy?

33. Won’t the installation process be disruptive to our business?




1. What are photovoltaics (PV)?

The word itself helps to explain how photovoltaics (PV) or solar electric technologies work. First used in about 1890, the word has two parts; ‘photo’ derived from the Greek for light, and ‘volt’, a measurement unit named after Alessandro Volta (1745-1827), a pioneer in the study of electricity. So PV could literally be translated into light electricity and that is just what PV materials do; they convert light into electrical energy.

2. How do we get electricity from the sun?

When certain semi-conducting materials, such as kinds of silicone, are exposed to sunlight, they release small amounts of electricity. This process is known as the ‘photoelectric’ effect. The photoelectric effect refers to the emission, or ejection, of electrons from the surface of a metal in response to light. It is this basic process that a PV cell uses to convert light into electricity.

3. Do solar panels work without direct sun?

Yes. Today’s systems work extremely effectively in the climate of north-western Europe. They are designed to maximise output from specific geographic daylight patterns and climatic conditions. Direct sunlight is not required, although orientation does affect performance. Even on cloudy days, there is normally enough so-called ‘diffused’ light for the solar PV panels to produce electricity.

4. How much carbon can I expect to offset through installing a solar PV system?

A 50kWp solar PV system in the south of the UK generates sufficient zero-carbon electricity to off-set approximately 20 tonnes of CO2 each year. That’s the equivalent to the average annual carbon emissions from the electricity of 12 homes.

5. What is a kWh?

A kilowatt-hour (kWh) is a unit of electrical energy. 1kWh is identical to 1 unit of electricity that is shown on your electricity bill. An electrical item having a power rating of 1kW will consume 1kWh for every hour it is operating at full power.

6. What is the difference between Power and Energy?

A kilowatt-hour (kWh) is a unit of electrical energy. 1kWh is identical to 1 unit of electricity that is shown on your electricity bill. An electrical item having a power rating of 1kW will consume 1kWh for every hour it is operating at full power.

7. What does MPAN mean?

MPAN (Meter Point Administration Number) is a unique number to the property. It is found on the electricity bill issued by your supplier. This is sometimes called a Supply Number but it should not be confused by your customer reference number. The full MPAN is 21 digits in length and should be printed in the format below on a recent electricity bill.



If an MPAN starts with ‘00’ then you can obtain a 12 month Half Hourly Data report (HHD spreadsheet) of all electricity used on site by emailing your Utility company.



Legal & Commercial

8. I understand that REI and the participating School/Business/Organisation (YOU) enter into a Power Purchase Agreement (PPA); how does this work?

The PPA is the agreement that delivers your discount of c.10-20% (depending on your current tariff) on the cost of all the electricity generated by the solar PV system which you consume on site. This agreement runs for 25 years.

9. Who owns the solar PV system?

REI and its Investors will own, monitor, manage and maintain the solar PV system that is installed on your roof.

10. There is a mortgage or other charge on the property. Do I have to tell the bank and will they approve the installation?

Yes. Before leasing your roof space we will seek consent from any lender who has a legal restriction over the property of your behalf. We have direct experience with most banks and as they are familiar with these schemes it is extremely rare for them to object.

11. I am a Commercial landlord and I have tenants in my building. Can I still take advantage of the REI Fully Funded Energy Scheme?

Yes. However, you will normally require approval from your tenant beforehand. If you are happy to share the benefit of the cheaper, clean, green electricity with your tenant, then there is little reason for them to object. Specific circumstances will apply and you should contact us for further information.

12. What happens if we move or sell our property?

If you move or sell your property within the 25-year term, the Lease of the roof space and the Power Purchase Agreement are transferred to the new building owner and they will then continue to enjoy the benefits of the discounted clean, green electricity the system generates.

13. What if we want to extend or develop our building?

If your development plans necessitate the removal of the solar PV system, we will agree with you a period of time during which you are able to undertake the work, on the basis that the solar PV system is re-instated afterwards. We will undertake the removal and reinstatement of the system at our cost; the repair work to your roof is to be undertaken by you at your expense.

14. I am a Commercial landlord. Do I, or my tenant, benefit from the discounted electricity?

Either scenario is achievable subject to the terms of the occupational leases. Landlords can re-charge tenants for the solar electricity they use, or allow their tenants to take the full benefit. We can advise on a full range of options that are available.

15. What happens if we don’t use all the electricity the solar PV system generates?

At times of peak generation, if you do not have sufficient demand on-site, the excess power is exported to the national grid. Equally, when the solar PV system is generating less than your total demand on site, the shortfall is made up through importing electricity from the national grid as normal. Depending on the size of your roof and your electricity demand, you should reasonably expect to consume most or all of the electricity generated from the solar PV system.

16. How will this system affect my insurance costs and cover?

The system installation should not affect your insurance cover at all; however you will need to notify your insurer that you are having the system installed. REI insures the solar PV equipment itself.

17. What happens if we need to repair our roof during the term of the lease?

If your repair necessitates the removal of part or all of the solar PV system, we will undertake the removal and reinstatement at our cost. The repair work to your roof is undertaken by you at your expense unless it has been caused by the PV system itself, in which case we would be responsible for all work and costs.

18. What if we want to buy the PV system from you during the term of the lease and receive the Feed-in Tariff ourselves?

We can provide you with the costs of buying the system from us during the term of the lease. You can achieve an attractive rate of return on the investment no matter when you decide to invest.

19. What if we have a fire, natural disaster or the system is vandalised?

The all-risks insurance will cover any damage to the system that results from such an event.

20. How can I be sure that we will be charged accurately for the solar electricity we use?

Our remote monitoring meters are fully accredited (MID Class 1 & Ofgem approved) products that record consumption down to very narrow tolerances. All our clients have access via the internet, to the live generation data so they can see exactly what solar PV electricity has been generated and how much has been consumed on site.

21. What is the cost of electricity produced by the system and does it increase?

The starting tariff (in pence per kWh) is adjusted annually by reference to Retail Price Index (RPI) and is exclusive of VAT and other regulatory charges. Typically we are able to achieve savings of 10-20% against a client’s grid electricity tariff.

22. Do I need to change electricity supplier?

No. You will continue to pay your current supplier for any electricity you require that the system does not generate for you.



Installation & Technical

23. Does my building need to meet a certain energy efficiency requirement?

Yes. Normally your building must achieve an Energy Performance Rating of D or higher. If required, we will we able to arrange this for you but the solar PV system we install cannot be included in this assessment.

By 2018 it will be illegal to lease a property with a rating lower than E, so we recommend all property owners start to consider how they can improve the performance of their buildings and a solar PV system may be one such improvement.

24. Is my roof strong enough for solar panels?

The installed weight of solar panels is typically between 14-15kg m2 including mounting equipment. This minimal additional loading rarely causes structural issues, but to be certain we undertake a structural survey on every building ahead of the installation.

25. Will our roof leak?

Our accredited professional installation partners follow industry standard methodologies and use tried and tested products to minimise any risk of damage to roofs. The installation warranty and long term Operation & Maintenance contract we provide covers any problems that may arise after installation. We also work with roofing manufacturers to ensure that our installations do not compromise existing warranties.

26. What happens if the system breaks down or develops a fault?

Our remote monitoring equipment will alert us to a fault immediately and it is our responsibility to resolve the problem under the terms of our 25-year maintenance contract. To minimise the risk of any such issues, we only specify and install high quality equipment supported by long term warranties and guarantees.

27. How much maintenance do solar panels need?

Solar panels have no moving parts and need very little maintenance at all. We monitor our systems continuously and arrange for the panels to be maintained when necessary to ensure optimal performance. In our experience, our panels are typically cleaned every 2 years.

28. Why should we trust your Company to be able to offer this solution, for 25 years?

REI and its Investors are experienced developers, owners and operators of electricity generating solar PV assets. The business relies on the continued high performance of our clients’ solar PV systems over the long term.

29. Can you fix solar PV panels to any roof?

There are a wide variety of fixing solutions that allow installation of solar PV to most roofs, including flat roofs. Pitched roofs should face between South East and South West and all roofs should be free of shading and structurally sound.

30. Do I need planning permission?

Unless your building is listed, planning permission for the installation of solar PV panels is not normally required below 50kWp. We will be able to confirm to you whether your building requires any planning consent and where required, REI will obtain any planning permission documentation at no cost to you.

31. Do I need to inform Building Control about the installation of a solar PV system?

Yes. We would liaise with Building Control and outline the planned installation in conjunction with the undertaking of a structural survey.

32. Are solar PV systems noisy?

Solar PV systems have no moving parts so the only noise is an occasional slight hum from the inverters.

33. Won’t the installation process be disruptive to our business?

No. Most installations will be completed within 3-5 days and there is often very little need for work inside your building that would cause any disruption to your normal working practices. You should expect everyone to take an interest in the installation though as it is an exciting change to your building.