Domestic Solar PV

Greenshop Solar is a long established renewables company delivering efficient, high quality systems in Gloucestershire, Wiltshire, Worcestershire and Oxfordshire, from its base on top of the Cotswolds, at Bisley, Stroud. Over 20 years experience of developing systems and pioneering new technologies have made Greenshop Solar the leading Gloucestershire installer.

Greenshop Solar is MCS Approved giving our customers access to the full range of  Feed in Tariff - FiT, and Renewable Heat Incentive - RHI payments. Our team are happy to offer solutions for Grid Connect and Off Grid systems, storage and even battery back-up systems.

If shading has proved to be a problem we can provide a range of inverters from Solar Edge that optimise the output from each panel, this minimises the effects that shading one panel has on the whole system. If you have shading issues on your existing PV installation we can install panel optimisers that maximise the output from each panel and negate the output reducing effect from the shaded panels. This can generate thousands of extra kwhrs and be worth thousands of pounds over the life of the system.

Another issue is energy security, when the grid electricity supply fails the PV system shuts down, an alternative is a different type of inverter and batteries that act as a backup supply. The length of time the backup supply will last is dependent on the number and size of the batteries and the size of the load. These systems can support the whole building or just "priority loads". It is important to secure a supply for the heating controls, the fridge/freezer and lights. If these continue in times of power cuts life is not too difficult.

Your first step - for domestic installations read "Brief Introduction to PV" below.

What a PV system gives to the customer is the satisfaction that they are producing some of their own energy and they can also, now, or in the future, upgrade to a storage, or backup system giving a degree of energy security and control over their supply. What ever system you install you will be lowering your carbon footprint.

Another thing to consider is the exported electricity, at the moment for domestic systems the government “deem” the value at 50% of the total generation figure. In reality if you have a 4kw peak system the likelihood is that you will be exporting 75%+ during the day because you will probably only be running the fridge and freezer so you are loosing out. We could fit a power diverter to heat hot water, this will divert the exported energy and that improves your use of your own generated energy and saves money. We have slight reservations about the fact that the carbon saving would be greater if solar thermal was heating your water and the electrical energy went back into the grid for others to use. Having said that, until you are paid the full export rate for exporting the energy the best financial saving is to use the energy. Storing the surplus energy in a battery for later use is a better way because it saves the energy for your use, and is more carbon efficient.

A system designed and installed by us...


A Brief Introduction to PV

A quick introduction and guidance into having a Photovoltaic (PV) system installed based around a 1kwp (the peak output) system:-

1.  A 1kwp system will cost around £2,000
2.  A 4kwp system will cost between £4,500 and £8,000 depending on the ease of installation and the make of panel and inverter specified. A 4kwp system will produce around 3800kwhrs a year in the south of England (Energy Saving Trust) but this will vary from year to year depending on the weather.
3.  1kwp will cover about 7 square meters of roof area with the lower cost panels and about 5 square meters with more efficient (and more expensive) panels.
4.  1kwp system in Gloucestershire will deliver about 850kwhrs of electricity in a year.
5.  A typical system will take 2 days to install and commision
6.  A typical house will use 3500kwhrs/year of electrical energy
7.  The system should ideally face South to target the maximum anual generation, but east to west will be OK – see tilt and orientation guide. Alternatively you may wish to target a morning, afternoon, or winter load so panels facing in different directions or at a steeper angle will ensure generation to meet target load times. As an example panels inclined at a steeper 55 degree angle south facing, will produce much more energy in December and January than panels set at 30 degrees. These days with a much lower Feed in Tariff rate it make more sence to target your load so additional panels facing east/west and/or a steep angle south facing provide energy at targetted times. 
8.  The ideal roof pitch to give maximum annual generation is 30-35deg, traditional pitches of 45º and 55º make only a few % difference in annual output  – see tilt and orientation guide. As said earlier you may wish to target a higher output in winter rather than the maximum annual figure, for this a steeper angle is better to catch the lower sun angle. Again see Tilt & Orientation chart >>

9.  Space is needed in the house for the inverter and the total generation meter - see picture.
10.  The total generation meter is the energy generation reading that gives you your FiT payment for the energy generated.  – see picture.
11. The system is fully automatic and will generate electricity when the sun shines.
12. When the electricity supply fails generation stops, so your system does not electrocute the man on the wire repairing the supply! Then it automatically starts working again after the grid supply returns and becomes stable. The system can be adapted to provide a backup supply in the event of grid failure. This involves a different, or additional inverter, more wiring and batteries.
13. Installing a solar PV system on a roof is a “Permitted Development” (excluding Listed Buildings) provided it is less than 200mm above the roof and complies with the General Permitted Development Order. AONB’s are not “Conservation Areas” in “planning terms” so even in AONB's solar panels on the roof are a permitted development. In “Planning Conservation Areas” solar systems do not need planning permission if they are on the roof, however if they are on the walls and can be seen from the highway Planning Permission will be required.
14. The installation price guidance above takes into account scaffolding, but not any building specific problems or any electrical wiring changes that may be required to your particular building.
15. The Feed in Tariff (FiT) currently gives an income from a typical 4kwp system facing south of about £170 per year under the scheme, plus a further 4.91p/kwhr for everything that is exported. PLUS some of the electricity generated will be used by the building at the time of generation which avoids paying for imported mains supplied energy - saving further money. Considering only the FiT (not the electricity used) as a return on capital this represents approximately 5-10%. This FiT payment rate is currently guaranteed by the government for 20 years.

Payment is index linked and TAX FREE under current legislation.

With the current Feed in Tariff payment rate of 4.18p/kwhr at the 10kwp and under rate, and with the cost to buy in electricity currently more, typically 15p/kwhr, it now no longer makes sense to limit your system size to 4kwp to maximise your return, if you have room for more panels. Each kwhr of electricity generated saves 0.526kgs of CO2. This CO2 figure varies daily depending on the generation mix in the grid supply.

Large systems - please contact us to talk through your project.