Solar Power System Design 101 (Volts)
One of the three basic measurements to understand regarding very basic electricity, and how it relates to solar power system design, is Volts. The other two are Amps and Watts.
Think of volts as pressure. When you open a water faucet or hose, the reason that water flows out is because it is under pressure. Volts is the basic unit of measurement for electrical pressure. There are technical definitions that precisely define the volt, but for the sake of keeping it very simple, just remember that it is ‘pressure’.
Photovoltaic solar panels are available in a variety of voltages. A typical solar panel is actually made up of an array of smaller individual solar cells which are are wired together (internally). Depending on how they are internally connected will provide a given ‘voltage’ at the output (with full sunlight shining on the panels of course).
Batteries also have a voltage rating. They too are often configured with multiple individual internal ‘cells’ that combine to present a given voltage output. The typical typical heavy duty deep-cell battery used in solar systems is ’12-volt’ (the same voltage as a typical car battery, although a solar power system battery is a different type of battery than an automotive battery). Actually, a fully charged ’12-volt’ battery of this type is more like 12.8 volts. There also are heavy duty deep cell batteries that are rated at 6-volts that are sometimes used in solar power systems. The batteries themselves can be connected together (battery bank) in ways that result in higher voltages (series-connection), or even lower voltages (parallel-connection), each with their own advantages and disadvantages (to be discussed in a follow-on article).
A voltage measurement (the number itself) requires that there are two points or sources of reference. To measure water pressure (pounds per square inch), the number is typically referenced to ‘zero’. To measure electrical voltage, the number is referenced to some point in an electrical circuit (which can be zero, or something else). When measuring battery voltage and solar panel voltage, we are measuring between 2 locations, typically positive and negative (red and black). The negative or ‘black’ terminal is usually the ‘zero’ potential, or reference point. Also, when measuring batteries and solar panels, we are making a ‘DC’ measurement (as opposed to ‘AC’). Without getting into it (another article), ‘DC’ stands for Direct Current, and is the type of electrical circuit that is found in the front end of solar power systems. Some systems will convert the ‘DC’ to ‘AC’ at the very end, in order to provide the same type of circuit that is common in most homes and appliances used within the home.
In order to measure volts, you need a volt meter. There are lots of them available.
‘Fluke’ has always been a top brand name. Even Radio Shack makes some decent meters. It is an absolute essential tool when working with solar panel electrical systems.
So, the very basic intention here is to get across that…
VOLTS is like PRESSURE. Simple as that.
Survival preparedness and self-reliance is a life style that encompasses many things, including the topic of energy. One of my many interests is alternative energy, namely, solar power. This article along with others in this titled series, is intended to provide simple, basic, easy to understand instructions, methods, tips, and examples for those who are interested in a series of helpful ’101′ type information in this area. Remember though… electricity can be dangerous. Consult a professional. Do your own due-diligence regarding any information contained within this page