Solar panel is best to top up your backup battery as you know the generators are very noisy, costly and smelly. It is a simple power backup that reduce the battery cost. However, it will not run your fridge but it can also with some extra energy and power storage, it will also keep your mobile battery charged and it is also used as an emergency car starter.

However there is a limitation of every battery system which is, every power supply will eventually end. Theoretically, it has 13 days for out of time. But question is that what happens when in catastrophic situations is grid power is not restored at the end of 13 days?

Answer is simple, that store the sun's rays and keep your battery topped up with an electricity producing photovoltaic solar panel.

Here is the procedure to go for it:

Step 1: Analyze and Calculate your Needs

Solar panel's out put is measured in watts. Match the solar panel with the battery. Thumb rule is used to choose the panel with the same number of watts as the same number of amp hours in battery. For example, a 55- aH battery like Optima we can comfortably pair it with a 55 watt or little higher out put panel.

A flexible laminate amorphous panel can pump out 68 watt in full sun.

Step 2: Select the right solar panel

There are two main factors which are necessary during purchase the things which are portability and cost. The solar panels with low wattage output at 12 DC is correctly matching the voltage of battery. Flexible panels are great for backup powers because they can be easily folded and roll up according to your need. But they are little expensive. But the U.S company has the cheap solar panels near about US $189.

Step 3: Now, Collect the Remaining Parts

Normally, you need a charge controller, it stops the battery from becoming overcharged and finally damaged by limiting the output of panel. It can also perform neat battery tricks like in the event of low battery, it interrupts the power.

A Morningstar's Sunsaver 10 amp controller costs US $48. The charge controller should exceed the output of panel by minimum 25 percent.

Other parts which you will need are: 12 AWG automotive wire which is called 'primary wire', yellow color coded wiring spades, large ring terminals, butt connectors, two pigtailed automotive style fuse holders, two maximum 20 amp fuses and associated tools like prob voltmeter, crimper and wire stripper.

Step 4: Now finally, Hook these all Up

This is the order to do:

The Load

 First you should cut the alligator off the end of plus which we used on the battery projects. Then strip a quarter inch from the ends of the wires and join the fuse holders tail to the red and positive leas to the butt connector. Now, add one spade to the other end of positive fuse holder and one spade to the end of black lead. Attach the black lead to the negative end of controller labeled 'Negative load' and red to the positive end labeled 'Positive Load'.

Now, the plug should be connected to the charge controller.

The Solar Panel

Now, cover the panel with the shipping paper or roll it according to your need to avoid to meet the cable with each other and then hook the solar panel to the 'Solar' terminals on the charge controller. Here is no fused is required.

The Battery

Now follow the instructions of wiring technique as I mentioned earlier to make battery connections for the controller terminals labeled 'Battery'. Now add a fuse holder at positive wire within 6 inches of battery.

Step 5: Find a Sunny Spot 

Finally, you should place your solar panel at the location where it can get and store the maximum sun rays and avoiding shade and place the charge controller and the battery with next to each other in shade. Then insert the fuses, load circuit fuse should be inserted first then the battery circuit.

Now you can check it and charge your devices. It will work efficiently.