Contact Chelsfield Solar and Chelsfield Electrical for solar electrical installations

Is your roof suitable for solar PV?

We install solar PV systems in the SE of the UK. This covers London, the Home Counties and the rest of the SE area up to North Oxford, Cambridge and Colchester area.

Orientation

Southerly facing aspects are optimum and the drawing below shows how the orientation will have an effect on the output of a solar PV system. This assumes an unshaded pitched roof of 30° to 40° (standard pitched roof).

Solar PV suitability

To check the orientation of your roof, two useful web sites are Google Earth or Local Live , These are both free but for Google Earth you need to download their software. Local Live does not need any software to be downloaded although it can be a little slower to load the pages.

Google Earth http://earth.google.com/
Local Live http://local.live.com/

Size

The size of the roof will dictate how much solar PV will fit and therefore how much electricity you will be able to generate. Different PV technology requires various areas but for a system connected to the national grid, the smallest area a PV system will take up is approx 7m2.

Positioning of solar PV

Penetrations such as chimneys, pier walls, dormers, veluxes and soil vent pipes will have an effect on where the PV could be positioned. Depending on the orientation of your roof, shading from chimneys and dormers can be significant so we tend to avoid the areas directly beside these as shading may substantially reduce the overall output of a PV system.

Pitched Roofs

PV panels or tiles should not be placed right up to the hip, ridge or eave of a roof. This is due to a number of reasons such as rain run-off should still be able to fall into the gutter (retrofit systems sit slightly higher than the roof tiles) and wind turbulence is greater at the roof edges and sides. The pictures below give an indication of the size of roof and how PV can be positioned.

Roof before solar PV

Plan of Solar PV

Solar PV installation

Roof before PV installation

PV Layout

Completed installation

Roof Tile Types

There are many different roof tile coverings and your tile type will make a difference to the fixing method - this is applicable for a retrofit system added on top of the existing roof covering. With a slate roof, the fixings will always need to be made from the underside of your roof whereas with all other tile types the fixings are made from on top of the roof.

Flat Roofs

There are a number of different methods of securing a PV array to a flat roof but it is generally easier to install to a new flat roof or one that is being re-weatherproofed.

One method is to build the PV array on an ‘A-frame’, which would be secured to the roof structure. For an existing flat roof, access may be required from the underside which may cause an issue if there is a plaster boarded ceiling as small access holes would need to be made in it. Fixing pads would need to be installed on top of the roof and weatherproofed by your roofer - we will provide details and drawings showing what is required. We would then install the PV array to the pads. Another method of fixing to a flat roof that does not require penetrating the existing covering is to have a ballasted system but we would need confirmation that the structure is capable of taking the additional ballasted weight, which is approx 70kg per unit (one unit per PV panel).


'A-frame' fixed to structure	Ballasted units	'A-frame' structure

Dimensions

We can give you an accurate estimate if you can supply some dimensions - even if it is pacing out the approximate width of the roof. We can estimate the remainder of the measurements from the photo you send of the most southerly facing aspect. The more information you can give us, the more accurate the initial estimate will be.

Please complete our Online Assessment Form or download an Assessment Form (Word doc) and enclose a photo and/or a dimensioned sketch of the most southerly facing aspect for a specific estimate for your own property.