Solar energy, or photovoltaics (PV), is a free renewable energy resource that can help businesses cut greenhouse gas emissions and their monthly energy bills.
PV cells convert sunlight into electricity by an energy conversion process. In most PV cells, photons in the sunlight hit the cells, where electrons are excited in the atoms of a semi-conducting material. Silicon is the most commonly used semi-conductor. The energised electrons result in the generation of an electrical voltage, where electrons flow to produce a direct (DC) electric current.
Solar PV systems are used on farms and other businesses, often in remote areas where connection to the electricity network is difficult or expensive. Solar PV systems can be part of a stand alone power system. These are not connected to the electrical distribution network.
Solar PV systems are also becoming increasingly popular in urban environments, where they can be connected directly to the electricity distribution network (grid-connected).
Solar PV systems work well in both rural and urban conditions. The best places:
- Get a lot of sunshine each year
- Have a generally clear sky, rather than cloudy.
Solar PV systems work best in north-facing places with year-round sun. They are usually installed on roofs but can also be placed on facades, conservatory roofs, sun shades, garages or specially-built stands on the ground.
Make sure your site:
- Faces north (south-facing panels are for the northern hemisphere)
- Is free from shade and exposed to good sun all year
- Has enough space – a typical 1 kW unit needs an area of around eight square metres.
If you are designing a stand alone power system you will probably need to combine your solar system with other generators, such as:
Estimating the cost of a solar PV system can be difficult because costs depend a lot on the site. Use this information as a guide only.
Typically, solar power costs somewhere between $6 to $9 per watt peak, so a 1kWp system will cost somewhere between $6,000 and $9,000. The cost of generating one unit (kWh) of electricity from a solar panel is calculated to be around 35c/kWh to 50c/kWh, although this can vary considerably.
The cost of installation and related equipment for stand-alone power systems, such as a battery bank, can increase the cost of the system significantly.
But the cost of solar power systems is expected to fall as production expands and technologies improve. At the same time, the price for grid electricity is expected to rise, so the cost-effectiveness of solar power should continue to improve.
More detailed information on generating your own electricity:
- Solar electricity generation
- Stand alone power systems
- Grid-connected systems
- Solar water heating systems.
See the EECA website for more information on Solar energy in New Zealand.