A solar charger employs solar energy to supply electricity to devices or charge batteries. They are generally portable.
Solar chargers can charge lead acid or Ni-Cd battery banks up to 48 V and hundreds of ampere-hours (up to 4000 Ah) capacity. Such type of solar charger setups generally use an intelligent charge controllers. A series of solar cells are installed in a stationary location (ie: rooftops of homes, base-station locations on the ground etc.) and can be connected to a battery bank to store energy for off-peak usage. They can also be used in addition to mains-supply chargers for energy saving during the daytime.
Most portable chargers can obtain energy from the sun only. Some, including the Kinesis K3, and GeNNex Solar Cell 2 can work either way (recharged by the sun or plugged into a wall plug to charge up). Examples of solar chargers in popular use include:
- Small portable models designed to charge a range of different mobile phones, cell phones, iPods or other portable audio equipment.
- Fold out models designed to sit on the dashboard of an automobile and plug into the cigar/12v lighter socket to keep the battery topped up while the vehicle is not in use.
- Flashlights/torches, often combined with a secondary means of charging, such as a kinetic (hand crank generator) charging system.
- Public solar chargers permanently installed in public places, such as parks, squares and streets, which anyone can use for free.
A solar panel can produce a range of charging voltages depending upon sunlight intensity, so a voltage regulator must be included in the charging circuit so as to not over-charge (over voltage) a device such as a 12 volt car battery.
Solar chargers on the market
Portable solar chargers are used to charge cell phones and other small electronic devices on the go. Chargers on the market today use various types of solar panels, ranging from thin film panels with efficiencies from 7-15% (amorphous silicon around 7%, CIGS closer to 15%), to the slightly more efficient monocrystalline panels which offer efficiencies up to 18%.
The other type of portable solar chargers are those with wheels which enable them to be transported from one place to another and be used by a lot of people. They are semi-public, considering the fact that are used publicly but not permanently installed. A good example of this kind of portable solar charger is the Strawberry Mini device.
The solar charger industry has been plagued by companies mass-producing low efficiency solar chargers that don't meet the consumer's expectations. This in turn has made it hard for new solar charger companies to gain the trust of consumers. Solar companies are finally starting to offer high-efficiency solar chargers. When it comes to permanently installed public solar chargers, Strawberry energy Company from Serbia has invented and developed the first public solar charger for mobile devices, Strawberry Tree. Due to a built in rechargeable battery which stores energy, it can function without sunshine or at night. Other companies such as Voltaic Systems, Poweradd and others have started to push better products onto the market as well.
Portable solar power is being utilized in developing countries to power lighting as opposed to utilizing kerosene lamps which are responsible for respiratory infections, lung and throat cancers, serious eye infections, cataracts as well as low birth weights.  Solar power provides an opportunity for rural areas to "leapfrog" traditional grid infrastructure and move directly to distributed energy solutions.
Some solar chargers also have an on-board battery which is charged by the solar panel when not charging anything else. This allows the user to be able to use the solar energy stored in the battery to charge their electronic devices at night or when indoors. An example of a mobile charger is by Germany-based company Changers, who created a separate charger and battery system that is mobile. You can disconnect the battery from the solar panel and take only the battery with you when it is fully charged.
Currently, foldable solar panels are coming down in price to the point that almost anyone can deploy one while at the beach, biking, hiking, or at any outdoor location and charge their cellphone, tablet, computer etc. As advances in the technology continue to be made, new products will be able to be expand into third world countries faster than ever before. Recently, billionaire Elon Musk unveiled a new battery system that may allow off-grid systems that rely solely on solar power to recharge them to be deployed anywhere on the planet, thus possibly ending the need for strictly grid-based energy systems.
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