At one time photovoltaic (PV) solar cells only use was to power communication satellites. But now days PV is commonly used as a alternative source of power for remote locations. These can be remote communications repeater stations, or a weather station. But now day's this can be a home that is located hundreds of miles from the nearest power line. The cost to extend the power line out to your home could be quite expensive. Utility companies typically charge four or five figures per mile to extend a power line out to a customers location. This type of cash outlay will buy a substantially large solar system. In this case the customer could save quite a bit of money.
How did residential solar electric power get its start? Remote homes traditionally did not have electric power. The ones that did used a gas power generator to provide for their electric power needs. But the problem with generators is they are expensive, and noisy to operate. Then their is the problem of transporting large volumes of gasoline. The constant sound of the engine does get annoying in a relatively short period of time. So remote home owners started to look for ways of reducing the time the generator had to run. They discovered that they could use deep cycle batters to supply low voltage electric power, and run the generator only when the batteries needed recharging. Remote home owners then discovered they could use solar panels to recharge the batteries. The result was they needed to run the generator less often. And by adding additional panels they only had to run the generator rarely. This is how the first residential solar electric systems got their start.

In this picture you can see a example of some PV panels that are roof mounted. PV solar panels are manufacture in wide variety sizes by many different manufactures. The solar panels produce low voltage DC power. DC power is good for charging batteries, but you can't run your TV on DC power. So what you need is a device called a power inverter. This converts the DC power into 120 volt AC power. 120 Volts AC is what the typical home uses for lighting and appliances.
PV systems can be divided up into two categories. Battery bases systems. The other is battery less systems.

Battery based PV systems store the electrical energy in deep cycle storage batteries. While battery less systems store their energy on the power companies power grid.
This is battery box in battery based PV system. Energy is stored in these 16 golf cart batteries for later use. In this system the batteries power a 4000 watt power inverter. The inverter converts DC power into AC power for the house.

 

Major components.
In the picture to the right you can see a battery based system.

Solar Charge Controller regulates the charging of the batteries. It's job is to properly charge the batteries using power from the solar panels.

Inverter converts the batteries stored energy into 120 volt AC power when needed. Inverter maximum power output is rated in watts.

Circuit Breaker is used to provide overload protection, and to power down the inverter.

Battery less system along with PV disconnect pictured at the right.

The advantage is that system cost less. Their are also no costly batteries to replace. The system is also more efficient. Storage is unlimited, because the power is sent back to the power line. If your solar system is producing more power than what your home is using will cause your electric meter to run backwards.
The disadvantage is that when there is a power failure the system will stop working.

Now there is hybrid type systems that once the batteries are recharged it will begin to sell power back to the power company.
The advantages of PV power is it's clean,and quite. The disadvantages is the cost of installing a system is expensive. And pay back time is not very favorable. The good news is prices are going down as sales volume goes up. Total sales increases at rate of 20% every year. And also energy cost continue to increase every year at a accelerated rate. It is possible in some states to get government rebates, that also help reduce system cost.
As for the future of solar PV it looks very bright.