When planning a solar photovoltaic (PV) installation it is important to understand the drivers behind the decision to install renewable power generation.
For some corporations solar PV and renewable power can form part of their Environmental plans and Corporate Social Responsibility programs and these can be important drivers within a commercial or public sector environment. For others it is about maximising revenue generation from available or leased roof-space such as on a datacenter, hospital or farm building. Within a domestic setting, solar PV installations provide an opportunity to reduce energy costs and demonstrate some eco-friendly credentials.
There is nothing to stop a solar PV installation from simply earning revenue from Feed-in-Tariff (Fits) FITs. Energy generated within the solar PV system can simply be exported to the National Grid. The generated electrical power, can also be used by the site, to reduce its electricity costs and feed into the entire site supply or dedicated systems. A combination set-up is normally adopted by most organisations.
In terms of a developing Smart-Grid, feeding solar PV generated power into the National Grid is one step towards this but in remote and rural areas, it can be more productive to deploy energy storage battery packs. These can store all or some of the generated electricity for later use (at night) by lighting and electronic systems including security, alarms, communications and small IT systems, when ‘normal’ electricity supplies may be sporadic or not available.
The amount of solar PV generated power is dependent upon the solar installation size and this is very often a function of the roof space and budget available. Typical PV solar panels are sized at 285-300W and are connected into a solar array which for a domestic installation can be up to 4kW. Larger solar farms and solar parks can reach sizes of several hundred kVA or even MVA.
When selecting the best location for a solar PV array, a south facing roof, angled at 30° from the horizontal is conserved to give the most optimum performance. The area for the solar panels should also be free of shade through out daylight hours and the roof itself capable of supporting the solar PV structure. Depending on its location, it may be prudent to install lightning and surge protection as part of the installation, and this is particularly relevant in rural and remote areas.
A basic solar PV system itself will consist of photovoltaic panels (cells) arranged in series and parallel strings into a solar array. The panels themselves will typically be roof mounted either directly through roofing brackets or to an angled framework. Each solar panel is inter-connected via a DC cable and connector (especially designed for solar PV panels) and a cable run taken to a DC isolator before a solar inverter. There should also be an AC isolator on the output of the solar inverter. The entire system including the solar inverter may also be remotely monitored over an SNMP or internet-based connection.
Small scale solar PV systems within a domestic environment can connect to the National Grid through a G83/1 relay (sub 4kW), whilst larger PV systems (above 4kW) on a corporate office or datacenter or leased farm roof will require connection through a G59 relay. Installation and connection should be made by an MCS (Microgeneration Certification Scheme) accredited installer and NICEIC certified contractor. They will complete the paper work required for approval of the installation by your local District Network Operator (DNO) for connection and FIT revenue generation.