Solar Power – Frequently Asked Questions


Solar photovoltaic (PV) cells are able to generate direct current (D.C.) through the absorption of energy from sunlight. Solar modules are comprised of an array of many semiconductor cells. Each cell has been chemically doped to produce two characteristically different boundaries (a base and an emitter), creating an internal electric field within the cell. When sunlight is incident on the cell, a portion of it’s energy is absorbed within the semiconductor material which can cause the excitation of electrons, knocking them free from the atoms. The built in electric potential of the cell will force these electrons to flow in a certain direction. This forms a current, and by placing metal contacts on the top and bottom of the PV cell, this current can be drawn off for external use. 

Multiple PV modules are arranged in a string, whereby the extracted D.C  is fed into an inverter that converts this into usable alternating current.

The size of the system will be determined through consultation with the client and will accommodate for many different factors such as their targets, projected future growth, budget, available footprint, current consumption and local grid constraints.

A detailed energy analysis is a foundation to the system design and it will ensure that we specify a system that will work well with the client’s usage profile, ensuring the greatest commercial return. 

Fundamentally, the financial return of a solar PV project is dependant on 3 main metrics: the lifetime cost of the system (CAPEX and OPEX), the cost per kWh that you pay for grid electricity (including inflation) and finally, the lifetime forecasted generation of the PV system. 

In reality, these elements are influenced by micro-factors and so we take a dynamic approach to financial modelling. Each project will be modelled on a bespoke investment calculator that allows sensitivity testing on all elements. In turn, this allows the client to become comfortable with the investment they are making. 

Most commercial roof-mounted PV systems fall within Permitted Development Rights (PDR) if they are below 1 MWp.

For a ground-mounted system (>9 sq m), or if your premises are in a National Park or Area of Outstanding Natural Beauty (AONB), then planning will be required.

It is still possible, however, listed building consent will need to be obtained prior to the commencement of any work. It should be noted that listed status makes a difference – Grade I is the most difficult to obtain consent for, followed by Grade II and then Grade III.

The location of the solar photovoltaic array also plays an important role. If the array is on the front roof aspect of a listed building (especially Grade I), it makes it less probable that consent will be granted.

On average the additional load of solar modules combined with the mounting equipment equates to around 13 to 14 kg per m2. Most modern buildings are suitable for solar PV, but we will still complete a full structural assessment, accounting for factors such as wind and snow in the region, to ensure the roof can take the additional loads.

There is no evidence to suggest that solar PV systems pose a greater risk than any other electrical equipment. However, it is highly important to ensure that all PV systems are correctly designed and competently installed by companies certified by the Microgeneration Certification Scheme (MCS). 

To help minimise associated risk in the case of a fire, we ensure that all systems have clear signage that makes the presence of a PV system obvious with indicators for safe isolation procedures. Access to site-specific schematics will also allow technicians and firefighters to quickly identify key elements of the system.

Silicon, extracted from silicon dioxide and silica sand, is the 2nd most abundant raw material on the planet. As a result, around 95% of commercial solar panels use silicon as the base semiconductor. Some alternate materials such as perovskite, cadmium telluride (CdTe) and Gallium Arsenide (GaAs) have seen increasing development over the last few years but still fail to compete on a commercial scale.

Developments in different technologies and manufacturing techniques over the years have enabled us to extract more and more power from solar cells. Efficiencies for single-junction silicon cells can be as high as 23%, approaching the theoretical limit of ~30%. Hence, when taking into account practical concerns such as light reflection, spectrum losses and light blockage from electrical contacts on the front of the panel, there is not much room for improvement. 

In terms of optimising technical design, we are constantly reviewing emerging technologies and module spot pricing to find a balance between lifetime performance and commercial return. We only specify Tier 1 modules which have a highly regarded reputation within the industry for quality and service. Tier 1 suppliers are more dependable when it comes to honouring product warranties and performance guarantees and also invest heavily in quality control to minimise defects in their production line, allowing for greater commercial return when it comes to full lifecycle system design.

We provide responsible and qualified project management for all phases of activity on each project. Our management team, operations and engineer consider the health and safety of all stakeholders to be the highest of importance. Along with our in-house capabilities we pay a retainer to an external health and safety organisations who conduct audits, site visits and advise on any complicated projects.

Detailed and job specific rams are produced and adhered to for each project along with task-specific Toolbox Talks. These are communicated at the pre-start meeting/ induction and continuously updated throughout the project. Each team has at least one SSSTS qualified engineer and a number of health and training certs including, but not limited to: Working at Heights, Working on Scaffolding, Asbestos Awareness, IPAF licences, Electrical Risks, Working on Roofs, hand tools, access and egress, COVID 19, manual handling and NEBOSH Level 3.

Our in-house project management team is governed by our ISO 9001 accredited Quality Management System that ensures our processes are constantly scrutinised and improved in continuous management meetings to improve operational efficiency and enhance customer satisfaction.

Energy Gain UK only specifies ‘Tier 1’ solar modules with European insurance-backed 25-year performance guarantee. The inverters we specify have a standard 5-year warranty that can be extended to 20 -years. Mounting equipment is warrantied for 20 years and we will guarantee our workmanship for 2 years as standard. 

One of the unique benefits of solar PV is that due to the lack of moving parts, general maintenance and operating costs are very low. We offer an Operations and Maintenance (O&M) contract which enables us to remotely monitor your array at all times, allowing our technicians to adjust parameters for maximum performance. If any component is underperforming, we can act swiftly, eliminating the risk of lengthy downtime.

The performance of a solar PV system should be monitored over time. This can be automated via monitoring software linked to the inverter and/or the generation meter. Trend analysis can be used to look for changes in performance which cannot be accounted for by normal changes in light levels. Larger systems can use reference cells and pyranometers to monitor light levels and the output can be used to give an indication of performance independent of light levels. A reduction in performance can relate to various factors such as system damage, new shading, and soiling of panels

If you have any more questions that have not been answered here, please get in contact and one of our consultants will be happy to help.