Solar electricity

You can cut your greenhouse gas emissions and energy bills for your business by using a free and renewable energy source, solar energy.

How solar PV cells work

Photovoltaic (PV) cells convert sunlight into electricity. The amount of electricity a solar PV system generates depends on the intensity of the sunlight it’s exposed to. It still produces electricity on cloudy days, but less than with direct sunlight.

Solar PV systems can be part of a stand-alone power system. However, they’re becoming more popular in urban settings, where they can be connected to the electricity distribution network.

Key solar PV system components

PV systems usually include:

  • PV panels, cables, and mounting or fixing hardware
  • an inverter and controller
  • batteries, back-up generators, and other components for off-grid situations
  • special electricity meters (for grid-connected systems).

Energy output of solar PV systems

Each solar PV panel is rated on its peak electrical output. For example, a panel with a 75W peak rating (75Wp) will have an output of 75W under test conditions. A well placed panel usually generates 2.5 to 5 times its rated power output per day. So a 1kWp panel can produce 2.5kWh (kilowatt hours) to 5kWh per day, or between 880kWh and 1750kWh per year.

Panels are typically available from 5 Wp to 300 Wp. A typical domestic solar PV system would be 1,000 Wp to 3,000 Wp, so you’ll have to buy a number of panels and connect them in an array to get the energy output that you need. You’ll need even more panels for a large commercial array.

Where to place PV panels

Solar PV panels are suitable in both rural and urban conditions. Panels are usually installed on roofs but you can also place them on facades, conservatory roofs, sun shades, garages or specially built stands on the ground.

Make sure your site:
●    faces north
●    is free from shade and exposed to good sun all year
●    has enough space - a typical 1kW panel needs around 8m2.

Cost to buy and install solar PV systems

As a rule, your site will need will need 8 sq m for a typical 1 kW unit. If you’re designing a stand-alone power system, you may need to combine your solar system with other generators, such as a small wind turbine, hydro system or biodiesel generator. 

The cost to install and buy equipment for stand-alone power systems, such as a battery bank, can increase the cost of the system significantly. However, we expect costs to fall as more systems are installed and technology improves.

Stand alone power systems - ENERGYWISE website