Once a distant technology that just sat on roofs that a few green minded people used, solar power has become a trendy tool we can hold in our hands. Sunlight - solar energy - can be used to generate electricity, provide hot water, and to heat, cool, and light buildings.

A typical solar system will reduce the need for conventional water heating by about two-thirds. Often the plumbing from a solar heater connects to a houses existing water heater, which stays inactive as long as the water coming in is hot or hotter than the temperature setting on the indoor water heater. When it falls below this temperature, the homes water heater can kick in to make up the difference. Incorporating passive solar designs can reduce heating bills by as much as 50 percent. High-temperature solar water heaters can provide energy-efficient hot water and hot water heat for large commercial and industrial facilities.

Many large commercial buildings can use solar collectors to provide more than just hot water. Solar process heating systems can be used to heat these buildings. A solar ventilation system can be used in cold climates to preheat air as it enters a building. And the heat from a solar collector can even be used to provide energy for cooling a building. The Co-operative Insurance Building in Manchester has the largest commercial solar system in the UK. I think it looks very futuristic and cool!

You can generate electricity for a single building like the co-op but there is the potential in the future to generate enough power for a power plant. The author of a recent Christian Aid report, John McGhie, said that for $50bn (£26bn) the whole of sub-Saharan Africa could be turned into a solar-generated economy. And $50bn is exactly the same amount as the continent would have to pay on extra fuel bills from oil," he said.

Electrical retailer Currys is about to add a new item to its usual array of washing machines and other white goods - solar panels. Currys is taking a risk as the solar panels will cost far more than anything else the store sells. They say it will cost the average three bedroom household about £9,000 to buy and install solar panels - compared to £16,000 in specialist stores. There are also grants available through the Low Carbon Buildings Programme.

What other solar gadgets can you buy?

Well, Sharp, the world's number one solar cell producer, has just turned its hand to glass studded with LED lights and cells. Instead of generating enough electricity to run a home, it creates a psychedelic light show at night, powered entirely by the day's sun.

You can also buy solar chargers for iPods and phones. Other recent outlandish additions include a solar-powered tent, scooter and LED house numbers, while mundane ones like bike lights, torches and radios have been around for years.

People can also use captured passive solar heat to cook food. A basic cooker consists of an insulated box with a glass top. Heat from concentrated sunlight gets trapped in the box and can be used to heat food enclosed in the box. These have not been very popular to date.