Solar power is a source of renewable energy. By harnessing solar energy we help save on the planet’s limited and fast depleting energy resources such as gas, petroleum, oil and coal. It is non-polluting and helps in lessening the greenhouse effect. Solar energy installed in your house could save you thousands of dollars in your lifetime by eliminating energy bills. Not only that, the local utility company will even credit you for giving them whatever surplus energy you generate.
Solar energy has been in use in some form of the other since prehistoric times. But it was only after the steep rise in oil prices that all major countries started exploring possibilities of exploiting solar energy. Solar energy can be harnessed either by photovoltaic or thermal conversion. With the former the solar energy is collected through panels called Solar Panels.
 PV Solar Panel Factsheet
A solar panel is a photovoltaic module that consists of multiple PV solar cells assembled together for practical and useful purposes. The panels are typically flat, and are available in various heights and widths. The typical use of solar panels is to generate electricity for residential, commercial, institutional, and light industrial applications.
Here is some basic information about solar panels.
- In the panel, the cells are connected in a series to derive higher voltages (in Volts). For example, if a single solar cell produces a voltage of 0.5V, a panel needs at least 24 cells, connected in series, to generate 12V.
- Usually a panel has more cells (for example 28-40 cells) to compensate for voltage drops or for charging batteries.
- The current generated by the panel (in amperes) is larger when the individual solar cell has larger surface area.
- If needed, connecting solar cells in parallel will also provide more current.
 How Solar Panels Works
The power output of a PV panel will depend on four factors:
- Peak power of panel (measured in peak-watts or Wp)
- Light intensity
- Number of hours the panel is exposed to the Sun
- Angle of exposure to the Sun
 Components Used to Provide Solar Power
To generate common 120 volt AC power required for daily use using solar power, four components are required. They are Solar panels, charge controller, battery and inverter.
Solar panels charge the battery, and the charge regulator insures proper charging of the battery. The battery provides DC voltage to the inverter, and the inverter converts the DC voltage to normal AC voltage. For 240 volts AC power, either a transformer is added or two identical inverters are series-stacked.
Most solar power systems will need a charge controller which diverts power away from the battery to ensure that it is not overcharged. Most charge controllers also incorporate a low-voltage disconnect function, which prevents the battery from being damaged by being completely discharged. It does this by switching off any DC appliances when the battery voltage falls dangerously low.
 Solar-Powering the World
Today thousands of families in the US are getting their entire electricity requirement from solar energy. California has over 30,000 home and small-business systems installed. In 2006 it launched the "Million Solar Roofs" program at an initial cost of $3.3 billion with the aim of adding 4,000-10,000 MW of solar over the next ten years.
Kenya, where about 30,000 small systems are sold per year, has the world's highest household solar ownership rate. Japan, which went solar in the late 1980s, implemented a remarkably coordinated, well-designed solar development and dissemination effort over the next two decades.
 Solar Energy for Your Home
The initial cost of installing a solar system in your home can be quite high (around $10,000 to $100,000). But this is a one time cost and you need not pay any more bills once the solar power system is up and running. Many governments also offer solar power incentives such as tax credits and aid for as much as 50% of your installation fee.
If you want solar energy to power your house it is not very difficult provided the roof of your house has the right inclination to take advantage of the sun’s rays. Non-tracking PV systems should be inclined at an angle equal to the area's latitude to absorb the maximum amount of energy year-round. If you have a house with an un-shaded, south-facing roof, you need to decide what size system you require.
 Reasons for Going Solar at Your Home
The main advantage of installing solar energy in your home is that you get electricity in conjunction with electricity from your current utility. A PV system can also be a source of alternate electricity for utility grid outages.
Alternatively, a PV solar system can be a single source of electricity for remote homes. For example, a PV system can be an excellent source of electricity for off-grid homes at a cheaper cost – if connecting to the grid will necessitate large amounts of investment. Here are some reasons for going solar.
- Take advantage of clean and renewable energy
- Decreasing cost - benefit from the evolving technology
- Fulfilling social responsibility for environmental concerns
- Take advantage of ASI, Green tag – increasing the property value
- Take advantage of incentives, rebates and tax credits
- Powering an off-grid home
- Enjoying alternate energy without increasing property tax
 Solving Solar-Power Issues
You will need to store surplus energy in batteries for use at nights and on days which are not very clear. And batteries are very costly. Another alternative is to connect your house to the utility grid. This way you can buy power when you need and sell it to them when you have in excess.
Another problem is that the electricity generated by your PV modules is not compatible with what is used by the electrical appliances in your house. The electricity generated by a solar system is DC (direct current), while the electricity supplied by your utility (and the kind that every appliance in your house uses) is AC (alternating current). You will need an inverter, a device that converts DC to AC. Most large inverters will also allow you to automatically control how your system works.
Solar systems have a 25-year warranty from the manufacturer. The rest of the system has 5 years’ warranty and inverters 10 years.
 Portable Solar Power
Portable solar power is best suited for use by for hikers, photographers, emergency workers, campers, mountaineers, backpackers, bicyclers, horse-back riders, and anyone who will be away from the power outlets. These devices can run or charge laptops, cameras, cell phones, batteries, lights, and other electronic equipment. They can also be used as home or car emergency kit. You can purchase portable
 The Future of Solar Energy
A 2008 combination of nano and solar technology has made it possible for solar electric generation to be even cheaper than burning coal. Nanosolar, Inc. has developed a way to produce a type of ink that absorbs solar radiation and converts into electric current. Photovoltaic sheets are produced by a machine similar to a printing press, which rolls out the PV ink onto sheets approximately the width of aluminum foil, and a hundred times thinner than existing solar panels. This is what has driven their costs down so dramatically.
Work is underway in the US on solar nanotechnology to make solar energy cheap and affordable to every household. It makes use of an infrared technology which makes solar energy work on cloudy weather too.
A Colorado State University unit AVA Solar Inc is expected to begin mass production of low-cost, high-efficiency solar panels. These solar panels would provide energy at almost the same cost as traditionally generated energy. The 200MW factory, which is expected to go on stream next year, will power 40, 000 US homes.
 Solar City in China
In China, Rizhao City, which means City of Sunshine in Chinese, solar water heaters are used in 99 percent of the households in the central districts, and over 30 percent in the suburbs and villages. More than 6000 households have solar cooking facilities in the area. More than 60,000 greenhouses are heated by solar panels in nearby areas.
In total, the city has over a half-million square meters of solar water heating panels, the equivalent of about 0.5 megawatts of electric water heaters.
This was achieved with the encouragement of the government which financed extensive research and development, and the initiatives of solar panel industries
 Solar Railway Station in Taiwan
The Taiwan Railway Administration is planning to install 13,000 square meters of solar panels on the west side of the Taipei Railway Station to generate 300 kilowatt-hour of electricity daily. Though it will be only a fraction of the total power requirement at the station, even a small saving of 5-10% will add up to a sizable amount in the long run.
 Solar Energy in Developing Countries
A United Nations Environment Programme (UNEP) solar photovoltaics (PV) pilot project in India provides several hours of uninterrupted lighting every night to 100,000 people living in poverty-stricken rural regions. Other countries like Algeria, China, Egypt, Ghana, Indonesia, and Mexico are inspired by the success of this project to improve energy access in their countries.
The UNEP project encourages local and national banks to finance small loans of $300 to $500 for installing a solar PV module storage battery, charge controller, interior wiring, and switches and fixtures with the capacity to power two-to-four low-watt compact fluorescent lamps (CFLs) and a DC fan.
 Solar Powering the US
A Silicon Valley solar power company, Asura, is gearing up to generate enough solar energy to meet the power needs of all Americans. The solar farm, which is to be built in California’s Mojave Desert, is also working on a solar storage technology to store energy for use during night time. The company is backed by a $40 million funding from Silicon Valley venture capital firms
 Solar Panels in Space
The US, Japan and some European countries are working on concepts and plans for building solar power plants in orbit that would beam electricity down for use on Earth. This is required as the earth has cycles of day and night and the solar panels don’t operate in the night or in cloudy weather. In orbit the solar panels can be so positioned that they receive constant sunlight.
Though this concept has been discussed since the 1960, nothing concrete has materialized as yet
 Common Questions on Solar Energy Installation at Home
What is a solar energy system?
There are two kinds of solar energy systems. For home use: solar water heating and solar electric. A solar water heating system preheats the water that goes into your existing water heater. This reduces consumption of gas or electricity normally required for heating water. With generation of electricity from the solar energy system you purchase less electricity from your power company.
What are the benefits of using solar energy?
It gives you full energy independence — energy is captured right where it is used, at your home. It is pollution free and safe for health and environment
Does solar add value to my home?
The value of your solar investment rises as your energy costs go up. Larger families can make higher savings. A 2kW photovoltaic system can trim 15 percent or more off your electric bill. Its resale price also adds value to your home.
What size system do I need for my house?
Biggest use of solar energy in homes is for heating water which can save 2,000 - 2,800 kilowatt-hours (kWh) (100 - 140 therms of gas) per year. That’s 60 percent of the energy used to heat water in an average home. Regarding electricity production, 1 kW of solar electric panels optimally oriented with minimal shade will produce approximately 1,000 kWh per year.
Is my house good for solar?
Though solar works best on south-facing roofs, east or west oriented low-slope roofs may also be good enough. Shading from trees, buildings, chimneys or roof gables should be avoided.
Can I install the system myself?
Your system must be installed by an eligible contractor.
 News and Current Research
- A colorful approach to solar energy: Dyed-glass breakthrough channels energy into solar cells 
- Solar Power
- Portland Online
- Renewable Energy Access
- Solar Power for Developing Nations
- Solar Energy in Taiwan
 Additional Information
- See video on How do people use solar power?
- See a film on Spray On Solar Power Cells on You Tube.
- Renewable Energy Access
- Guide: Get Your Power from the Sun