Solar Electricity using photovoltaic cells

A solar cell or photovoltaic (PV) cell is a device that converts sunlight directly into electricity by the photovoltaic effect. Their construction is completely different to solar panels for hot water which use pipes to collect the heat from the sun. Solar cells are made from very fine layers of silicon which produce electricity when the sun strikes their light absorbent material. This is achieved via a chemical reaction that produces electrons generating an electric current.

The most common application for a PV cell is a Solar Powercalculator and anyone who has used one will know that they work in very low light. You don’t need direct bright light but ambient light is acceptable. Solar cells have many applications from road signs to aeroplanes to Solar Power cars to satellites to domestic properties.

Solar power system

The term ‘Solar Revolution’ is basically the idea that one day all our electricity will come from the sun. More and more households are taking advantage of this ‘free’ electricity by placing solar cells on the roof of their properties that are wired into their electric system. Solar cells not only generate free electricity for the home owner but when you produce more than you use, you can sell it back to the electric companies so it actually make you money. The production of solar photovoltaic (PV) cells around the world has risen five fold since 2002 and increased by 40 percent in 2007 alone as prices of solar panels has decreased.

A question most people have when considering a solar power system is how many solar panels will I need to power my house? To calculate the area of solar panel required you need to know

  • 1) How much power the house consumes on average.
  • 2) Where the house is located (to calculate mean solar days).

The average amount of solar radiation falling on each square meter of earth is around 1000kWh per year - of this, it should be possible to collect between 20% (depending on the efficiency of the cell) Therefore, 5 square meters of solar cells are required to produce 1000kWh of electricity.

The oil industry uses price per barrel as its unit of price measurement. The solar energy industry typically uses price per Watt Peak (Wp) as its primary unit of measurement. The prices for high power band (>125 watts) solar modules has dropped from around $27/Wp in 1982 to around $4/Wp today. The kWp need to be translated to kWh (a measure which takes account of solar conditions) to calculate the cost of the system.

Some simple examples are that a 1kWp System will produce approximately:

  • 1800 kWh/year in Southern California
  • 850 kWh/year in Northern Germany
  • 1600-2000 kWh in India and Australia

In time, a residential Solar electricity system will pay for itself and possibly make you money and has the added bonus that your energy is from a green, environmentally friendly source which helps reduce your carbon footprint.