A Basic Introduction to Solar PV Systems
It's a tempting prospect for most home owners to harness the power of the sun to get free energy. Many of us have thought about heating and powering our home for free, and selling the excess energy back to the power companies. On the surface it seems like an easy decision to make, but there are several terms and concepts that need to be understood first.
The term Photo-voltaic or PV essentially means a process that turns daylight into electrical energy. This is the type of system built into a solar panel. Solar panels are also known as Modules. They are made from a layer of silicon cells that are interconnected and form an electrical circuit. This layer is sandwiched between a black glass sheet that faces towards the sun and a base made from a polymer resin material. When the panel is exposed to sunlight, the circuit is energized and electricity is produced. Solar panels are usually 60-cell modules for domestic applications, while larger facilities tend to have a slightly larger 72-cell model. If multiple panels are connected together they will feed into a combiner and from there into a charge controller.
Generally solar panels are located on a roof to maximize exposure to the sun. Any natural light will generate electricity even on a cloudy day, but direct sunshine will generate more. The electricity generated by the solar panel is DC or Direct Current. In order for the energy to be used safely, it needs to be converted into AC or Alternating Current. The device used to change from DC to AC is called an inverter and it is generally located inside the roof space underneath the solar panels. The inverter is fed DC from the charge controller. There will also be a need to install a pair of isolator switches or circuit breakers into the system. These switches should be located both before and also after the inverter for additional safety.
Once the system is ready to generate power it's a good idea to install a battery bank unless your county offers a decent Net-Metering program. This series of deep cycle batteries will most likely be located in the loft space with the rest of the system. There are a few different types to choose from. RV or Marine batteries are designed for small recreational systems and they will be of little use in a domestic capacity. A better choice is a heavier industrial battery. These are Lead Acid batteries and can still considered to be deep cycle due to the thicker plates inside. There are three options that are ideal for a Solar PV system, they are Flooded, AGM or Gel types. Of these three, most professionals would agree that AGM or Absorbed Glass Mat batteries are superior, although they are the most expensive.
Whichever type of battery is chosen, they will have to be wired up together. How they are wired up will effect how they perform. As a rough guide if they are wired in parallel, it will increase power. If wired in series it will increase voltage and if wired in series and parallel it will increase both. The type of wiring required will differ depending on the requirements, but most domestic users would usually wire their system up in series and in parallel.
On a day to day basis you won't be going into your loft space to check the system, unless of course there is a problem. The main method of interacting with your solar PV system will be via a PV Generation Meter. This unit is usually wireless these days and will be located wherever you need it in your home. The meter will provide up to date information on the kW currently being generated, and if your home is connected to the grid, how much excess energy is being exported.
Now you understand the basic components necessary for the effective implementation of a Solar PV system. A system like this will require further research and planning to install but, at least now the terms will be more familiar. With a little regular maintenance a Solar PV system can prove to be a great investment as it will last for many years to come. (Solar customers save around an avg. of $100,000 over a 30period)