How to choose a solar charger - buyers guide.

OK, so you have decided to buy a solar charger, but which is best for your needs?

Don't really know what features to look for? Well, that depends on what you want from it. Do you want to use it indoors on a sunny window sill? or do you intend to leave it in your backpack to use outdoors? Ecopia solar chargers are versatile enough to be used anywhere but they do have varied features for special uses like the SBC06 solar charger that has suction pads that stick to a window.

Does it have a charging socket? As an example let's say you want to use a solar powered charger to charge a digital camera. Whether you can use a universal solar charger to charge it depends on the charging system of the camera. Does it have a power charging socket or do you need to remove the battery to recharge it?
If it is recharged via a charging socket then it can be charged by a universal solar charger. Cameras that require the battery to be removed and charged externally can only be solar charged by certain types of solar battery chargers.

Solar charger voltage

Will the solar charger have enough power? Look at the nameplate data on the original camera charger. The nameplate data are the technical specifications engraved or stamped on the charger. All electrical devices should have this information.

On a typical digital device's charger you will see something like INPUT AC240V 50Hz 2A / OUTPUT DC4V 200mA. We are only interested in the output specifications.

In our example of the camera the output from the charger is a direct current (DC) voltage of 4 volts and the output current is 200 milli-amps (mA) or 0.2 amps (1000 milli-amps equals 1 amp).

The output from the charger is the electrical power that is fed to the battery charging circuit through the input socket. Therefore if we want to substitute the original charger for a universal charger like a solar charger then we need to ensure that the output voltage is at least 4 volts.

It can be higher, say 5 volts or even 6V, but not much more because then it might damage the battery or burn out the charging circuit.

An output voltage lower than 4 volts would not have enough power to energise the camera's charging circuit.

The output current (amps) is not as critical a parameter, it is more of an indication of how rapidly the battery would be charged. As a rule of thumb if the output current is halved then it would take twice as long to charge up a battery and if the current were doubled it would take half as long, all other things being equal.

Excessive current will overheat of the battery during charging and should be avoided because overheating will shorten the life of a battery. But it is unusual for a solar charger to supply excessive current so you should select a solar charger with a higher output current.

Solar charger connectors

Will the solar charger have the adapter tips you need? The next consideration when selecting a solar charger is to provide a proper connection from the solar charger to the camera's charger input socket. We need a suitable power plug adapter for the digital camera.

The connector adapter ensures the positive and negative leads of the solar charger's output cable connect with the positive and negative terminals of the charger socket on the camera.

Most cameras have a charging socket that accepts a round pin plug of about 4 mm diameter so measure the diameter of the connector on the original charger and choose an adapter that matches it.

A good solar charger will have an assortment of connectors for various devices and others can bought if the one you require is not packaged with the solar charger.

Larger Solar chargers

What if the battery is charged externally? If you need to remove the camera battery to be charge it with an external battery charger will requirea larger portable solar charger that can generate 12V and an inverter to change the 12VDC to get 240VAC.

An inverter is a type of transformer that changes DC current into AC current. They are used in larger solar power systems to provide AC electrical power to household appliances from the DC supplied from the solar panels.

Inverters come in various sizes and types, you will only need a small one to power the charger via its AC plug.

Some devices may also be supplied with a car charger which can plug into a solar panel with a cigarette lighter (CLA) socket.

Now that you know the solar charger requirements for you application it's time to see what is available.

The usual personal solar charger has an output voltage of about 5 volts and output current of about 500mA. This will allow you to charge most mobile phones and Ipods.

Some mobile phones require a bit more voltage, for instance some motorolas will only accept a charging input of 5.5 volts or more, but generally speaking just about all solar chargers will charge up any mobile phone if you have the right power connector adapter for the phone's charging port.

Solar chargers and portable solar panels are available in many designs and sizes for various applications.

The latest solar chargers will enable you to recharge mobile phones and other personal devices like Ipods and MP4 players. These handy solar powered chargers enable you to use just one charger to replace the jumble of chargers and cables cluttering up your home.

Solar chargers range from pocket-sized solar cells with internal batteries that are suitable for charging mobile phones and personal devices to larger portable solar panels designed to charge up an external battery to provide power for portable appliances when traveling or camping.

Choosing the right Solar charger

When choosing a solar charger bigger is better.

A large solar panel will generate more electrical current and charge up a battery faster than a small solar panel.

Similarly a larger storage battery in the solar charger will hold more charge and enable you to get more charges out of it.

Therefore a larger solar module will charge up the solar charger's battery quicker and a larger solar charger battery will hold more charge and provide longer use before having to recharge it.

This is the general rule of solar voltaic power generation; when selecting any solar power system from the smallest pocket sized charger to the largest solar power installations bigger is always better.

A solar charger with a 2 watt solar panel will product twice as much current as a 1 watt solar panel and a battery with a capacity of 4 amp hours (Ah) will hold twice the charge of a 2Ah battery.

Check the output volts
Another important consideration when selecting a solar Charger is the output voltage.

Types of solar charger

Most mobile phones require about 5 to 6 volts to recharge so the solar charger needs to be able to supply the required voltage.

Some solar chargers output voltages are adjustable to supply different voltages to charge up a variety of portable devices.

Therefore you may need a charger that can supply 9 volts to charge up some digital cameras, but only need 5 or 6 volts to charge your mobile phone.

Larger portable solar panels supply 12 volts.

This is the same as a car's CLA socket so these portable solar panels are suitable for electronic devices and small appliances that can be charged or powered via a 12 volt CLA supply.

MPPT Solar chargers

Its interesting to note that some solar chargers don't have internal storage batteries. For instance the Soldius solar charger does not, instead it has advanced electronics for direct charging, called MPPT technology, a first for small solar chargers.