FAQS

Frequently Asked Questions for Grid Connected Solar Rooftop Systems

Q. What is a Solar Rooftop System ?

In a solar rooftop system, the solar panels are installed on the roof of any premises that includes residential, commercial, institutional and industrial buildings.

Q. What is a Solar Rooftop System with Storage (Battery-bank) facility ?

A roof top system can optionally have storage (Battery-Bank) facilities. The electricity from solar and grid is stored in battery-bank, under normal conditions. In the event of grid shutdown or unavailability of solar electricity (such as bad weather), power is delivered through battery for specific duration.This can also be useful to deliver solar electricity after sunset (i.e. evening or night). In the region where grid is unavailable, then battery-bank must be installed with solar power system.

Q. What is working Lifespan of Solar PV System ?

Solar PV System is a static system i.e. it does not consists of any rotating or moving parts. So it is not prone to any kind of mechanical damage caused due to the friction, which is very common in generator or a motor. A Solar PV System can easily last for 20 to 25 years and can even work for a longer period if maintained properly (i.e. kept clean and no physical damage occurred).

Q. How Solar PV System is better compare to Diesel Generator as a backup system ?

Though the initial capital cost of a PV System is higher than a DG System, a DG System accounts for high recurring fuel cost and maintenance cost. While a PV System doesn’t require any fuel and its maintenance is very minimal and easy. It only requires dusting and cleaning of PV panels on regular intervals. Apart from this a Solar PVV System is environmental friendly and clean energy option for a backup system.

Q. What kind of maintenance schedule do I have to follow to keep the Solar PV System in a healthy Condition ?

A Solar PV System requires very minimal maintenance from the owner and is very easy to maintain. Regular cleaning of the Solar Arrays should be carried out, so that the system works at its full efficiency. Further intermittent checks should be done to ensure that there is no shading over the Solar Array because of obstruction. Apart from Solar Arrays, all other components of the system should be kept in a shaded area. These small steps can result in a healthier and longer life span of your Solar PV System.

Q. If the Solar Arrays are the only electricity producing unit in the system, then why do I need other components to make the system work? Doesn’t it add to the cost of the system ?

Yes, it is true that the only electricity-producingunit in the system is the Solar Array. But the electricity generated by the Array is in D.C. form and have to be converted into A.C. form so that it used by the consumer. Also to safeguard appliances, premises and consumers and avoid any damages, a safe and appropriate flow of the electricity must be implemented. Hence additional components are added to the system that provide protection and ensure better reliability.These components add marginal costs to the system.

Q. What happens to the power production on an overcast day ?

A Solar PV System doesn’t require direct sunlight to be able to work, though direct sunlight gives the maximum efficiency. The system continues to work even during the overcast conditions but the over-all efficiencies get marginally reduced, typically to 70%. But in a place like India that receives more than 300 sunny days per year, overcast conditions is not a major concern.

Q. How much do I have to invest for a Solar PV Rooftop System ?

The cost of a Solar PV Rooftop Setup depends on many factors such as the connected load, type &total available roof area, etc. The good quality grid connected solar PV System estimated to costs Rs. 0.8 Lac per KW, while a battery connected system costs around Rs. 1.25 Lacs per KW.

Q. If I invest in a Solar Rooftop Setup, in how much time will I make my money back ?

In a Solar Rooftop System, the major investment is its installation cost.It has a minimal maintenance cost and no fuel cost. A 5 KW Solar PV System has average pay back period of 4 to 5 yearsapproximately. The life span of a PV System as high as 20 to 25 years, hence 70 to 75% power produced by it may be considered as the free electricity.

Q. How much Roof Top Area do I require to install a Solar PV System ?

It is mandatory for a Solar PV Setup to have a shade free area duringentire time of the day. The Solar Panel Efficiency defines the area required for Solar PV System. Generally, a Solar Panel with 15% efficiency requires 100 sq.ft. of shade free roof area for ?KW. While a Solar Panel with 12% efficiency needs approximately 125 sq.ft. of shade free roof area for ?KW.Another factor that defines the area requirement is total weight of Solar Panels array and roof’s load bearing capacity. For very old and poorly built buildings the Panels have to be scattered in a larger area so that the construction can withstand their weights.

Q. Does the ambient temperature effects the efficiency of a Solar PV System ?

Counterintuitive to the belief amongthe people, an increase in the ambient temperature around the Solar PV System results in decrease in efficiency of the system. It is to be noted here that though PV Systems work on the energy from the sun, they work on sun’s light energy and not on its heat energy. The increase in temperature may result in lesser output voltage produced by the system, which in turn results in the decreased efficiency of the system.

Q. How does shading affect the performance of a Solar PV System ?

Shading has a very large impact on the performance of a Solar PV System. Since a Solar Panel is made of large number of Solar Cells, shading on a small part of it can have a cascading effect as the energy produced by the rest of the Solar Panel may be consumed by the part which is under the shade. Therefore, it is mandatory to install the system in a shade free area.

Q. What is Net Metering? How can I be benefited from it ?

Net Metering is a policy that allows the unused power produced by the Solar PV System to be fed to the Grid to which the system is tied to. This allows the system owner to get concessions on his electricity bills as the amount for units fed to the grid will be deducted from the amount of units actually consumed by the owner and the billing will only be done for remaining part of the units.

Q. What will happen in a situation when the power in the grid is out ?

A typical Solar PV System is designed to shut down if the power in the grid is out. This is done so that in case of maintenance any personnel don’t get electrocuted because of the power fed to the grid by the Solar PV System. But systems can be designed that can redirect power to a battery backup system from the grid in case of a power failure in the grid.

Q. Are there any Government rebates that I get for the installation of a solar PV System ?

To promote the use of Solar Power in India,there are several schemes from the Central& State Government of India thatoffers rebates to owner.MNRE (Ministry of New and Renewable Energy) provides 15% capital expenditure subsidies to residential households and 30% to educational,health & NGO institutions, post installation of Solar PV system.For commercials and companies Accelerated Depreciation is available under the Income Tax Act for Rooftop PV Systems. This allows savingof tax on income and reduces net costs of Solar OV systems. Apart from that there are other incentives and rebates that are provided by the individual State Government that are specific to each state.

Q. Why should I setup a Solar PV System at my premises ?

Setting up a Solar PV System at your premises provides youself-sustainability and you are not depended on the grid to supply you the required electricity. In longer run, you are substantially saving on your electricity bill generating your own power. Further you can sell electricity to already power deficit grid in the country and play important role in fulfilling the electricity requirement of the country. Also a PV System is a clean and environmental friendly for Power Generation. To sum up, it is a reliable, economic, social and environmental friendly form of Power Generation.

Q. While buying Solar Panels online, should I take my desired output rating equivalent to the KW (peak) rating given in manufacturer’s specifications ?

KW (peak) rating in the manufacturer’s specification is actually the output that a Solar Panel will generate in the optimum conditions which isachievable in a lab. Under practical situation to achieve peak output is improbable.For practical purpose, Solar Panels actual KW rating needs considering of 15-20% lesser than peak ratings. So Solar Panels with a higher rating are always considered during installation.

Q. While looking for Solar PV Systems online, I found a system of 1 KW output of Solar Array and 5 KW rating of Inverter considered as a 5 KW system. Can it really produce 5 KW ?

The output given by a Solar PV System is determined by the output received from its solar panel. Though an Inverter of 5 KW rating can be installedwith 1 KW Solar Array but its output will never exceed 1 KW as it is the maximum output that can be produced by the Solar Panels. However in future additional solar panels can be added to generate 5KW, as Inventor can work up to 5 KW rating.

Q. If I buy a Solar PV System online, how will I get to install it ?

Small Solar PV Systems available online that serves the purpose of powering small equipments generally comes with a ready to install kit and guide. But it is recommended to hire a professional help for the installation of a large PV System as there is a risk of faulty installation and may results in fatal accidents.

Q. Does the Solar Products comes with a Warranty against the manufacturing defects ?

Solar Products from reputed companies generally comes with a manufacturer’s warranty, though the warranty time period differs forevery component and from each company. A battery generally comes with 2-3 years warranty, while inverter generally has 5 years warranty. The warranty period for solar panels can goes up to 25 years.

Q. What is an Output Warranty? What Output Warranty should I expect from a Manufacturer ?

An Output Warranty is the Guarantee provided by the manufacturer that a certain percentage of output would be generated by its Solar Panels over Specific period of time. An Output Warranty may last up to 25-35 years post manufacturing of the Panels. For a good quality Solar Panels, the Output Warranty is expected to be 90% of the output for first 10 years of the manufacturing and 80% of output from 11 to 25 years.

Q. What Product Certification should I look for while buying Solar Products online ?

Product Certifications should be checked before buying any solar products online to ensure better functioning of the product. The major standard certificates for components are as follows. For panels- IEC 61215/IS 14286 (design qualification and type approval), IEC 61730 (safety); for Inverters- IEC 61683/IS 61683 (efficiency), IEC 60068-2 (environmental testing); for Charge Controllers- IEC 60068-2 (environmental testing); for Junction boxes- IP 54, IP 21 etc.

Q. How do I decide the Output Rating of the Solar PV System that I want to buy online?

The output rating of the PV system should be known beforehand while buying any component online. The total mVA value of the components that needs to be connected should be determined and then divided by the power factor it gives. This gives the KW rating of the system. The system of approximately double the value of the KW rating should be brought, to account for high startup currents of the equipments and losses in the system. It is always recommended to consult correct professionals, before buying Solar PV System.

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