Household use of solar photovoltaic (PV) panel systems has grown significantly in India this decade behind increased awareness of the risk of dangerous climate change, the reduced cost of systems and a range of government incentives to encourage use of the technology. Solar power systems are now an affordable option for Indian households looking to reduce their power bills and generate their own clean electricity. With the increased range of products and suppliers on the market, being an informed consumer has never been more important. This guide provides an introduction to solar PV systems so you are better equipped to make choices about a product that is right for you. Towards the back of the guide there are a series of questions you can ask your installer, electricity retailer and distributor to ensure you have all the information you need to make smart decisions.

Solar Photovoltaic (PV) panels are generally fitted on the roof in a south direction and at an angle to maximize the amount of sunlight that hits the panels. Solar PV panels on the roofs of homes and businesses generate clean electricity by converting the energy in sunlight. This conversion takes place within modules of specially fabricated materials that make up the solar panels. It is a relatively simple process that requires no moving parts. In most cases solar panels are connected to the mains power supply through a device called an inverter. Solar panels are different to solar hot water systems, which are also mounted on household roof-tops but use the heat from the sun to provide hot water for household uses. The technology to convert sunlight into electricity was developed in the 19th century, but it was only in the second half of the 20th century that development accelerated behind the need to provide reliable supplies of electricity in remote locations

The cost of solar panels has continued to change over the past decade behind different government incentive schemes and increased diversity in the panels, inverters and suppliers on the market. Being an informed consumer is increasingly important. Similar to buying a car or a computer, you’ll want to be sure that your system is a sound investment that best meets your needs at a reasonable price.

It is important to be clear on what you want from your solar PV system. Are you after a system that will partially offset your energy consumption for 5-10 years before requiring a system upgrade? Or do you want a system that will completely offset your household’s electricity use for the next 25 years? Like buying a second-hand car as opposed to a brand-new sports car, these two solar PV systems are both sound investments depending on your needs, but will vary significantly in price.

• Government rebates and support schemes (these vary in each state)
• Location
• Number of panels
• Orientation of panels
• Type of panels
• Type of inverter
• System design and configuration
• Transportation costs for equipment and parts
• Contractor installation costs
• Removal of trees or other shading
• Type of roofing (for example, tiled or tin)
• Height of roof
• Site preparation needs (for example, condition of roof or ground)
• Structural engineering, architectural, and other professional services (for commercial systems)

• The physical unshaded area available for the installation of your panels
• How much you are prepared to spend
• What portion of your electrical consumption you wish to generate.

To work out what size solar PV system you require, you need to analyze your household’s daily electricity consumption. Your monthly or quarterly electricity bill measures your household’s electricity consumption in kilowatt hours. From this figure, you can calculate your average daily electricity consumption, and the average amount of electricity your solar PV system needs to produce to cover your electricity needs. This process will be completed by your accredited designer during the design and specification stage, as part of their load analysis.

Solar PV panels come in different wattages. The main issues are your budget and whether the solar panels will physically fit in the space you want to install them. Each solar panel is approximately 1 meter long and 0.8 meters wide. A 1kW solar panel system will require around 8-10m² of roof space, and a 1.5kW solar panel system requires around 12 m². This will vary depending on the type of panel installed on your roof.

There are three main types of solar panel available, each with their own benefits. During the design and specification stage, your accredited designer will help you choose which type is the best to suit your needs:

Solar PV panels produce most power when they are pointed directly at the sun. In India, solar modules should face South for optimum electricity production. The orientation of the panels will often have a greater effect on annual energy production than the angle they are tilted at. A minimum tilt of 10° is recommended to ensure self cleaning by rainfall. For grid-connected solar PV power systems, the solar panels should be positioned at the angle of latitude to maximize the amount of energy produced annually. If your roof’s slope is not ideal, your accredited designer can create an appropriate mounting frame to correct the orientation and elevation of your panel. Failing this, the designer can advise you on the difference in energy output for different tilt and orientation.

The amount of energy in sunlight that a solar PV panel receives over a day is expressed in peak sun hours. As the amount of energy generated by a panel is directly proportional to the amount of energy it receives from sunlight, it is important to install panels so they receive maximum sunlight. Our accredited designer will calculate the amount of energy generated by the solar PV panel from the peak sun hours available. Peak sun hours vary throughout the year.

Solar PV panels should ideally be in full sun from at least 9am to 3pm. They should not be placed in shaded areas and be kept free from dust and dirt. Even a small amount of shade from things like trees, roof ventilators or antennas - will have a large impact on the output of a panel, as it changes the flow of electricity through the panel. Shading or dirt on just one of the cells in a solar panel results in a loss of power from many cells, not just the one that is shaded.

The amount of electricity a solar PV panel can generate is reduced as temperatures increase. Solar panels operate best at ambient temperatures up to 25°C. However, if the ambient temperature is higher, the panel’s output declines.

Following the design and specification you may request a quotation for the design and installation of the system. The quotation could provide specifications, quantity, size, capacity and output for the major components, including:

• Solar PV modules
• Solar Batteries
• Solar PCU/Inverter
• Cables and Junction box
• Mounting Frames
• Structure
• Any additional metering
• Data-logging
• Travel and Transport requirement
• Other equipment needed
• Any trench digging
• System user manual

The quotation should also specify a total price, together with proposed start and completion dates. The quotation should form a basis for your contract with the designer/installer. In addition, a contract for the supply and installation of the power system should be included with the quotation.

• An estimate of the average daily electricity output (in kWh)
• The estimated annual production
• The estimated production in the best and worst months
• The responsibilities of each party
• Warranties and guarantees, including installer workmanship schedule of deposit and progress payments.

When signing a contract with your designer/installer, you need to be informed. Important questions to ask include:

How many systems has the designer/installer completed?
How many systems similar to your system has the designer/installer completed?
When was the last time the designer/installer completed a system? New products are constantly entering the market. A designer/installer who has completed several recent installations will probably be up-to-date on the newest products and the latest regulatory issues.

What kinds of warranties come with the products?
Which warranties are your responsibility and which are the manufacturer's?
How long have the equipment manufacturers been in the PV industry? Long warranties are meaningless if the manufacturers aren't around in five years.

What performance guarantees do you get for the system as a whole?
How will you know if your system is performing to its maximum potential on a day to day basis?
Does the designer/installer provide some kind of optional service agreement?
If problems arise with your system, what services will the designer/installer provide and for how long?
Will the designer/installer be readily available to troubleshoot and fix problems?
If something goes wrong, who is responsible for repair or replacement costs?
Who is responsible for maintaining the system?
If you are responsible, what kind of training will the designer/installer provide?
Will basic system safety issues be explained?