A solar panel (photovoltaic module or photovoltaic panel) is a packaged interconnected assembly of solar cells, also known as photovoltaic cells. The solar panel is used as a component in a larger photovoltaic system to offer electricity for commercial and residential applications.
Because a single solar panel can only produce a limited amount of power, many installations contain several panels. This is known as a photovoltaic array. A photovoltaic installation typically includes an array of solar panels, an inverter, batteries and interconnection wiring.
Photovoltaic systems are used for either on- or off-grid applications, and for solar panels on spacecraft.
Types of Solar panel systems
System1.GRID TIED
Components:Solar panels,Inverter,Net Meter,Circuit Breaker
Grid tied systems work by connecting your solar energy to the electricity grid.You generate solar power and sell the excess power back to the grid.
The advantages of this system is that it is cost effective and you can sell your power when you aren't using it.The disavantages are that you cannot store your solar power.So if there is a power cut,you will only have power if it is sunny outside and your solar panels are making power.
System 2.OFF GRID POWER SYSTEMS.Components:Solar panels,inverter,circuit breaker,batteries,charge controller,backup power
Off grid systems mean you are not connected to the grid-you live in a remote area.These systems are more expensive as you will need storage for your power in the form of batteries.Off grid systems also require a backup power source.You wiil need backup power if you have many rainy days in a row that use up your stored battery power.
Backup power can also be useful for unexpected heavy power usage-for instance if you have many people to stay at one time.
System 3.GRID TIED WITH BATTERIES
Components:Solar panels,Inverter,circuit breaker,batteries,charge controller,Backup power,Net metering.
The grid tired with batteries system is when you are connected to the grid and you have batteries to store your solar energy.
This is a system where you get the advantage of selling excess power to the grid.Yo also have emergency backup power for when the grid goes down.
If you live off the grid-solar panels are usually a better investment than power cabling to connect to the grid.As a rule thumb-if you live more than 1 mile away from the grid,the cost of connection will be about the same as the cost of a solar system.
Deciding the best type of system for your home
A solar system gives you "free power",unlike the grid,where you are paying for power by the watt.If you live on the grid there is one thing to consider-do you get frequent power cuts?If you do get frequent power cuts,then a grid tired system with batteries will provide emergency backup power for when the grid is down.
Otherwise,a grid tired system will give you the benefits of solar energy and bill savings,without the added expense of batteries.Batteries add approximately 20-30% onto the cost of a grid tied system.
The Advantages of Solar Power
The major benefit of using solar power is that it is free to use, and for all practical purposes an unlimited resource. I believe that the last estimate of the remaining life of the sun was five billion years. Imagine not having to pay the increasing cost of electricity for years – solar panels are guaranteed for their output for 20 to 25 years, and are expected to last much longer before needing replacement.
Solar power is quiet and non-polluting, and produces no greenhouse gases. You can enjoy your life, at least in your house, knowing that you are not contributing to global warming. The fact is that you are reducing the pollution caused by conventional electricity production by not requiring it for your house.
When you decide to go solar, you also have the advantage that the Federal government and other institutions are willing to provide major help with the costs. This is in the form of tax incentives, grants and rebates. In some States, the financial assistance in the form of grants and rebates can amount to more than half the costs.
Laws have been passed that allow you to store your excess electricity with the utility company, and use it later, when the sun isn’t shining. This is called the “net metering” law, and it’s available in most areas, and being implemented in others.
If you use solar power for your heating, whether by a direct heating system or by generating electricity with solar panels, you have the advantage that you won’t run out of heating oil or propane by forgetting to order it.
An often overlooked benefit of installing a solar system is the increase in the value of your home. A study some years ago suggested that you add more than $20 to your home value for every dollar saved each year. Saving say $100 per month in electricity bills would therefore increase your home’s worth by $24,000, which might even be enough to pay for the installation, after rebates. In fact, the increase in value should probably be more than that, as the original calculation was based on higher mortgage rates than currently enjoyed, and on an assumed stable energy cost.
Finally, solar can do what the utility companies cannot. If you want to live in a remote place where the utility company doesn’t exist, you can do so – as long as the sun shines there during the day!
Solar Powered Home
As you’re interested in solar power for your home, have you ever wondered what would be the ultimate solar powered house, if you were to design it from scratch? First, we probably want to agree on what would constitute the ultimate solar powered house. Let’s say that we want to have a house that is cool in summer, that is warm in winter, where we can do all the things that we currently do – use computers, watch television, cook meals, etc., and we want to spend the least we can on conventional energy, if anything. Obviously, in the real world there has to be a trade-off between capital cost and energy saving or convenience, but for the ultimate house we can safely ignore this practicality.
What things are going to be important in designing this house and its solar systems? Ease of use would come high on my list, as I don’t want to have to run around changing the settings of things with any change of weather or other circumstance. I don’t want too much “high tech”, because that gives you more things to go wrong, and it’s harder to find the problem and fix it. I’m also concerned about where the house ought to be. If we put it in Arizona, we get lots of sunshine, but we do have a pretty hot summer (over 110°F), and the nights get cold in the winter, typically having a 30-40°F “diurnal swing”, which means the difference between the peak daytime and lowest nighttime temperatures. On the other hand, if we site the house in Massachusetts, we could be facing a much colder winter, with temperatures barely above freezing.
Okay, enough of this teasing. Take a look around you; do you like what you see? If you do, consider this your (potentially) ultimate solar powered house. No moving, finding new jobs and new schools for the kids, nada. Your own house can also be your ultimate solar powered house; it just needs a little work.
Start by looking at your energy use. Have you changed your light bulbs to compact fluorescent yet? Unlike our hypothetical case, you’re going to have to pay for the solar installation, so you’d better keep down the load and the size. Consider also turning off items that have a “standby” command, as they still use electricity in this mode. If you have an older home, look seriously at the insulation to see if it can be improved, and replace leaky seals round doors and windows. Then just go for it. Review the available information, pick your system, and make sure you qualify for all the rebates and grants. Make your home your ultimate solar powered house!
Solar Water Heaters
You’ve left a garden hose in the sun, and nearly scalded yourself when you turn it on? Well done, you’ve discovered solar water heating! Well, actually, you didn’t discover it, as solar water heaters have been used for at least a hundred years. It’s an appropriate use of the sun’s power, making use of it for our needs.
The modern solar water heater is little different from the types first used. The modern solar collector is often made up of a series of pipes fixed to a backing plate, painted in a dark color, and covered with glass which may have a special heat-trapping coating. This is called a flat plate collector, and it can go on the roof, like a photovoltaic, or electric, solar panel, although it is a bit thicker and may be heavier when full of water.
As with conventional solar power, before you install a solar water heater you may want to check on reducing the requirements, by installing water saving faucets, etc., to keep the size down and the performance up.
Solar water heating can be installed with a few variations on the theme. One version involves using an additional pre-heating tank to be heated by water circulated through the collector, and this tank supplies the incoming water for your regular water heater. The normal water heater will then, by the usual means of gas or electricity, additionally heat the water as necessary to the required temperature as set on the thermostat. Another means is to have a water heater with an internal pipe coil through which the solar heated water flows, heating the stored water indirectly. Most methods involve using an electric water pump, although in some circumstances you can arrange for natural circulation (that is, hot water rises) to circulate the water. Generally this doesn’t work, as the hot water is on the roof, and thus needs to go down, not up.
There are a couple of things to watch for when planning a system, although it really is basically as simple as described above. It is possible that the water in the collector can get too hot, and make the stored water hot enough to scald you. You will need to have a method of avoiding this. Often this is done by mixing the too hot water with the incoming mains cold water to produce the correct temperature before delivery. The other potential problem is the water freezing in the collector. This can be overcome by what is called a “draindown” system, where the collector is drained in cold weather, or by using antifreeze with the indirectly heating system.
Solar Powered Air Conditioning
Of course, there is a slight problem. By its nature, sunlight is more inclined to produce heating than cooling. We shouldn’t allow this to deter us, after all, it’s just a matter of engineering.
Conventional air conditioning requires electricity to power the unit, which includes a compressor to provide the work necessary for a refrigeration cycle. In a conventional air conditioner, the cooling is achieved by refrigerant evaporating inside the piping – evaporating cools a substance down, as it takes the heat from its surroundings to enable it to vaporize. The refrigerant is a high pressure liquid going into the evaporator, where it is allowed to expand and evaporate. The evaporator piping is actually in a unit that blows air into the room, so it cools the air. Refrigerant is just a chemical designed to evaporate at the best temperature and pressure for the cycle to work. When the vaporized refrigerant gets to the next part of the cycle, it is compressed with the compressor, which makes it hot and at high pressure. It goes into a condenser unit (the outside part on a split air conditioning system) where it gives up heat to the outside air, which makes it liquid again. The high pressure but cooler liquid goes back to the evaporator, where it evaporates again.
So one way to provide air conditioning with solar power is to generate electricity, and use that power to drive a conventional air conditioning system. But there is a problem because the whole traditional air conditioning system with the compressor described above is very power-hungry!. A typical 9,000 BTU air conditioning unit for a small room consumes about 850 Watts of electricity. That's a lot of electricity (and pretty expensive) to generate with solar panels! However, there are two alternatives:
Evaporative cooling: In places with dry climate, you can use solar panels to power evaporative cooling systems for your house. These consume much less energy to operate but they do not work in humid climates.
Absorption cycle: There is an alternative refrigeration cycle, and a Spanish company has just incorporated it into a small unit that can be used for a house. If you have an RV, you may be familiar with the refrigerator which is powered by propane gas. Refrigerators that run on natural gas have also been available for years for residential use, but never became very popular. These use a different sort of refrigeration cycle, and it uses the chemical lithium bromide as a substitute for the compressor. This is actually a chemical absorbent, so the refrigeration cycle is called an absorption cycle.
The company has designed all this into a unit, where the heat for the absorption cycle is provided by hot water, which is generated by a solar collector. There’s just a minimal electrical requirement to run the unit, and you can have cooling from heat!
