For a solar panel, I have saved one in my ebay wishlist, here it is 12 Volt, 50 Watt Solar Panel ( Solar PV ). 3, 5, 10, 20 watt panel available. | eBay
Though, I have been doing some online research for quite some time now, for a planned Alternative Energy source for my home, I don't have any practical experience with that, as I'm still doing some research, before making such a hefty investment into that. So, I'll suggest you to do some research before making an investment.
What I have found and understood till now, with some research for past 2 years is that the hardware is important. Here are a few points, that, I feel, everyone, thinking to work in this direction should consider
Things to buy-
1. A solar panel: It is the most important component of such a setup, and also, pretty expensive, as around 50-55 percent of the overall costs are of the solar panels.
a. The higher the wattage, the lower is the charging time and also, the larger is the battery bank. (You may get a maximum of 6 sunshine hours, that too depending on your location.)
b. The higher the voltage, the larger is the battery bank, as it can charge more batteries simultaneously. The voltage will decide the configuration of the connected batteries (either parallel or serial)
c. The solar panel, you choose, should preferably be of a minimum of 14% efficiency. The maximum, commercially produced solar panels have achieved is around 18 percent, so, don't expect to get too much. The less efficient solar panels may be cheap initially, but will not be cheaper than the ones with higher efficiency, in the long run.
d. The solar panels are divided into two types based on the materials used to manufacture the solar cells, of which the panels are made up of. The solar cells are either Monocrystalline, or Multicrystalline aka Polycrystalline. The monocrystalline cells are more efficient than the polycrystalline cells, so will practically produce more electricity per unit area, and thus will save you precious space, but are expensive than the latter.
e. Whichever solar panel you choose, the panels should contain reverse current blocking diodes, which are very important for protecting the panels getting damaged as a result of reverse flow of current through the panels.
2. The Solar Charge Controller
The Solar Charge Controller, is nothing, but a simple circuitry to harness the power from the solar panels and charge the batteries. While choosing a charge controller, you should keep in mind, the upgradeability. If you are planning to increase the panels, you should purchase a charge controller keeping in mind the capacity till which you're going to add the solar panels. Also, MPPT, (Maximum Power Point Tracking) is a good add on, if you're investing ample amount in such a setup.
MPPT as per Wikipedia, is:
Maximum power point tracking (MPPT) is a technique that grid-tie inverters, solar battery chargers and similar devices use to get the maximum possible power from one or more photovoltaic devices, typically solar panels, though optical power transmission systems can benefit from similar technology. Solar cells have a complex relationship between solar irradiation, temperature and total resistance that produces a non-linear output efficiency which can be analyzed based on the I-V curve. It is the purpose of the MPPT system to sample the output of the cells and apply the proper resistance (load) to obtain maximum power for any given environmental conditions. MPPT devices are typically integrated into an electric power converter system that provides voltage or current conversion, filtering, and regulation for driving various loads, including power grids, batteries, or motors.
Link to the Wiki article: Maximum power point tracking - Wikipedia, the free encyclopedia
3. Batteries: Since the setup is working during day time, you'll need batteries to store power for use during the non functioning phase of the system, i.e. during night. Deep Cycle batteries are better suited for this application. The battery bank, should be chosen, while keeping in mind, the other factors, including the solar panels, and the load the setup's going to serve.
Apart from these, there are a few other factors like the Wires, the distance between the solar panel, the charge controller and battery bank. Also, the intended use, may need you to buy an inverter, to convert the DC voltages supplied by the batteries to AC power for use in AC appliances.
These are some important things, which I could recall at this point of time. There may be some other things, that I might have failed to mention here.
So, I'll suggest, before making any investment (even the smallest one), give yourself some time to study, how a solar power generation system works, then try weighing the options available with you, and the usability of that system.
