Solar chargers convert the sun's energy into DC current in order to charge batteries. They can be mounted to a fixed structure or portable. When mounted to a fixed structure they are generally referred to as solar panels, and they are often connected to the electricity grid so they can supply electricity to the grid when there is too much to use immediately or store in the batteries they are connected to. However, portable solar chargers are not connected to the grid and are used solely for charging batteries or devices such as cell phones and laptops. They can usually be used even in low light conditions (although the charge rate will usually be slower), and are becoming increasingly popular for providing back-up and emergency power when travelling, camping or on the road. They are generally trickle chargers, which means that they charge batteries slowly and the risk of overcharging (which causes damage) is small.
It is fairly easy to make one's own solar chargers, and instructions for how to make a battery charger (pictured left) can be found in this solar battery charging guide, with more information on making a range of types of chargers available here. However, for those solar power users wanting a more elegant and easily portable solution, such as that shown to the right, there is a wide range of ready-made solar chargers available online.
Portable solar chargers have been developed for a range of applications and devices, from charging car and boat batteries to keeping laptops and cell phones operational while away from grid electricity. However, it should be noted that the smaller wattage chargers, which are generally smaller in size, charge batteries more slowly than the larger and more expensive chargers, so when buying a charger it is advisable to work out the best compromise of price, size and charge speed for your requirements. Another factor to consider is whether the charger contains batteries of its own or not. If it does, it will charge up those batteries and can then be used at any time to charge your device, but if it doesn't contain batteries, it can only be used when there is sufficient sunlight.
There are many online suppliers in South Africa, such as Sustainable.co.za, the green shop and those listed here. Some are specific to particular devices, while others, such as the one sold by iwarehouse.co.za, come with a range of connectors for different devices. Some are rigid and others are flexible, and the smaller chargers can be attached to backpacks for charging while hiking, or placed on the dashboard of a car or anywhere that receives direct sunlight. It is even possible to buy a gadget which measures the intensity of the light and tells you how good the conditions are for charging. Prices range from as little as two or three hundred rand for the smallest chargers, up to several thousand rand for the bigger ones.
Other sources and useful links:
Solar Phone Charger Blog: http://www.solarphonechargerblog.com/