What is a Solar PV panel ?

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A photovoltaic solar panel will convert sunlight directly into electricity There are no moving parts, exhausts, noise, or pollutants involved in the process. It is beyond the scope of this paper to explain the process in detail, but suffice it to say that light striking the front of a solar cell will produce a voltage and current.

A typical solar cell may be a 4 inch diameter wafer, about .01 inches thick. A group of these cells interconnected creates a solar panel. A typical solar panel can produce about 16 volts and 3 amps , or 52 watts, of DC power. Other module specifications are available, and such specifications will vary between manufacturers. Solar panels, in turn, can be interconnected in series or parallel to create a solar-array and any voltage-current combination required.

That's it! That's all you need to know about photovoltaic solar panels to contemplate a photovoltaic system.

But now it is necessary to control and utilize the resulting power obtained from the modules.

SYSTEM COMPONENTS

BATTERIES
Since P.V. panels produce power only when the sun is out, something must be done to provide power when the weather's bad or at night; batteries foot the bill. The panels basically power loads during the day, and the batteries provide load power when the panels cannot. The solar panels must also, of course, recharge the batteries so they(the batteries) can be utilized again.

Generally, lead-acid batteries are used in P.V. systems. While it is perfectly feasible to use a standard car battery in this application, it is wise to consult a knowledgeable source as to which battery is the best to use. There are many battery choices P.V. system. Factors to consider when choosing a battery are:

MODULE MOUNTS
If you want to, you can throw your P.V. modules on the ground or just lay them on your roof. However, such a practice isn't recommended for obvious reasons, especially after considering how much money you may spend. Module mounts perform several functions:

CHARGE CONTROLLERS
Generally , a P.V. system is sized so that more energy is produced than is consumed. If left to itself, this excess energy would overcharge the batteries, shortening their life. Charge controllers monitor battery condition and decide what to do with the power available from the P.V. panels. The charge controller function is equivalent to the system's owner watching the battery voltage all day and deciding when to disconnect and reconnect the P.V. panels to the batteries. This relatively boring job can be done automatically and indefinitely by a charge controller.

A charge controller can also prevent too much power from being removed from the batteries by automatically disconnecting loads or issuing visual or audible low-voltage warnings. Without such precautions, batteries can be damaged by deep discharge.

METERING
It is important to have some type of feedback to indicate what is happening within the P.V. system. The easiest method for accomplishing this is with meters. Basic things to monitor would be array current and battery voltage. These two measurements would indicate what the array is producing and the condition of the battery, I.E., state of charge.

LOADS
The end result of all of the previous work is to power loads. Loads can be items such as:

Since the P.V. system will be producing DC, only DC-type loads will operate directly from the batteries. If it is necessary to run AC loads, a DC to AC inverter will make the proper conversion. Several things to consider when choosing an inverter are:

SYSTEM SIZING
When utilizing a P.V. system, it is important to realize that one is dealing with a limited amount of energy. It is necessary to create an energy budget, that is, one must insure that over a certain period of time, at least as much energy is produced by the solar panels as is consumed by loads. Such factors as yearly average weather conditions, latitude, and load requirements enter into sizing requirements. It is a good idea to contact an expert to perform sizing calculations when installing a P.V. system.

CONCLUSION
That's about it for the basics. You now know what a photovoltaic solar system is and what it does. If you are contemplating the installation of a system, it is suggested that you do at least two things:

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