Solar Photovoltaic Energy FAQs

What Solar PV Mounting Methods are available?

PV modules can be mounted on a roof, in a roof or on the ground.


This is generally the cheapest and most popular system. Different roof fixings are used for different types of roof, including flat roofs. Generally for a domestic pitched roof, brackets are fitted to the roof timbers at spacings of 1.2m apart, in rows. A connecting rail is fitted to the roof hooks, and the modules are clamped to the rail. On-roof solar PV design takes into consideration wind and snow loadings for the different locations.

The modules can be mounted in portrait or landscape format, depending on available space. We recommend 300mm clearance on all roof aspects to allow for wind loadings.

On-Roof Solar Photovoltaic Panels


This is generally a good option if constructing a new build and concerned about aesthetics. These modules are specialist modules with specialist roof flashings. The outputs of in-roof installations are slightly lower owing to reduced efficiency resulting from heat build-up within the module.

In-Roof Solar Photovoltaic Panels


We can install modules onto a frame. This can be either a specialist metal frame or a bespoke wooden frame. The frame is fixed onto the ground, using piles, concrete strip foundations or ballasted concrete.

Ground-mounted Solar Photovoltaic panel installation

Flat-roof system

We can install modules onto a flat roof using a frame or console bins. These systems are generally ballasted and do not penetrate the roof covering. We allow for local wind conditions and ballast accordingly.

How does Solar PV work?

The solar modules each have an open circuit voltage (VOC) and a short circuit current (ISC), and are fitted with a bypass diode on the rear of the module. This allows maximum power point tracking (MPPT) to ensure that the maximum power is extracted from the module. VOC * ISC = Pout (Power Output).

The modules are connected in series in strings, much like connecting batteries. The VOC of each module is added together and then multiplied by the ISC for that string. The ISC is proportional to the sunlight hitting the surface, so more sunlight = more ISC. The PV modules produce DC (Direct Current) power.

Please note: shading affects the performance of the module; and shading one module will affect the output of that whole string. So ensure that shading analysis is done before you buy solar PV.

MPPT tracking graph

What are the components of a Solar PV system?

A PV system comprises outdoor components and indoor components.

The outdoor components include Solar PV modules, the roof or ground mounting kit, DC cable and DC connectors.

The indoor components include DC cable, DC switches, Inverter, AC switchgear and meters, and consumer unit breakers. The inverter converts the DC power into AC (Alternating Current) power to be used in the property.

What types of solar PV modules are available?

There are two main types of solar PV modules:

Monocrystalline and Polycrystalline Modules


Mono, or one piece of silicon. In appearance, has a black surface with white or black diamonds. Generally of higher efficiency than Polycrystalline modules.


Many pieces of silicon. In appearance, has a blue surface with lots of horizontal and vertical lines. Originally these were considered of lower quality and efficiency, but the Poly modules have improved greatly over the last five or so years, and efficiencies are now close to those of Monocrystalline.

Other types of solar are thin film and also hybrid modules which use different technologies, such as the Panasonic HiT modules.

What are the Efficiency Ratings of Solar PV modules?

Modules are generally classed as being standard or high-efficiency. The output of the modules is rated in Watts Peak (Wp). A standard module is approx. 1.6m high by 1m wide.

At the moment, standard outputs are in the region of 300Wp. High-efficiency modules give higher outputs for the same physical area, such as up to 450Wp.

Contact Gregor about Solar Photovoltaic Installations

Are you interested in getting a solar photovoltaic energy system installed in your home or premises? Don’t delay, call Gregor today on 0117 935 2400, and ask to speak to our Renewables team. We look forward to discussing your solar PV needs with you and to booking you in for a survey if you would like one!

Return to main Solar PV page.