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Solar Rooftop PV Plant Installation

Solar Rooftop PV Plant Installation

A guide to starting solar rooftop installation business in India

The Indian government has set its sights on having 175GW of non-hydro renewable capacity (made up of 60GW onshore wind, 60GW utility-scale solar, 10GW bio energy, 5GW small hydro and 40GW rooftop solar) by 2022. At present, this figure stands at just 60GW.

India is accelerating development of renewable energy projects to provide cheap, reliable and clean power to its 1.3 billion people. The country’s per-capita on-grid electricity consumption increased by 22 per cent over the four years ending March 2017 due to increased industrial activity, higher uptake of electrical appliances by residential electricity users and addition of new consumers to the grid—according to a report by Bloomberg New Energy Finance (BNEF).

Majority of the capacity in the 2022 target—a total of 135GW—is utility-scale (wind farms and solar parks, in particular). The BNEF report estimates that India will need to invest $83 billion to build this capacity. The good news is that, because of falling capital costs per MW, that figure is $19 billion less than BNEF’s previous estimates.

But some of the most interesting activity will be in small-scale solar, that is, rooftop solar installation. According to BNEF, rooftop solar in India will grow inevitably with or without the support of power distribution utilities. India will need to invest $23 billion over the next five years to meet its 40GW rooftop photovoltaics target by year 2022.

The cost of electricity from solar rooftop PV has halved in the last five years due to fierce competition in the market and drop in equipment prices. In contrast, average retail electricity rates have increased by 22 per cent during the same period. This has made rooftop PV cheaper than commercial and industrial grid tariffs in all major states of India.

However, BNEF expects residential sector PV growth to pick up rapidly post-2021. At the moment, its attractiveness is being held back by the requirement of high upfront capital expenditure, shortage of financing options, and the fact that grid electricity is cheaper for residential consumers with low consumption.

BNEF experts also indicate that net metering is a far more important enabler for residential small-scale solar than business-scale projects.

Annual solar rooftop PV installations in India; India’s financial year is from April to March
Fig. 1: Annual solar rooftop PV installations in India; India’s financial year is from April to March (Source: Bloomberg New Energy Finance, industry surveys, Ministry of New and Renewable Energy)

Homeowners usually draw less power during the hours when their PV panels are producing, making self-consumption much harder. Solar projects also have a big and untapped potential to power irrigation pumps and reduce the use of back-up diesel generators. Huge growth of rooftop solar presents business opportunities in rooftop solar system installation.

This project report provides a brief overview of solar rooftop PV plant installation service. Thus it acts as a guide on how to start a business in this area.

Components required

Components of a solar rooftop system are the same anywhere in the world. That said, however, some components make more sense for some regions than others.

For regions such as India and Africa that are keen to use rooftop solar as a source of backup power during grid power outages, batteries could be required at least in select cases. For developed countries such as USA and the European Union where grid outages are rare, batteries are usually not required as backup, with grid supplying the deficit power.

Block diagram for a grid-connected solar rooftop PV plant
Fig. 2: Block diagram for a grid-connected solar rooftop PV plant

Similarly, some regions of the world require use of trackers for rooftop solar as their rooftop areas are smaller than required to meet their power needs. For some other regions, trackers might not make a good business case.

Process flow for a grid-connected rooftop PV plant
Fig. 3: Process flow for a grid-connected rooftop PV plant

Key components of a rooftop solar plant include:

Solar photovoltaic modules (panels)

There are two kinds of modules, viz, thin-film and crystalline. Rooftop solar plants predominantly use crystalline panels because these are more efficient and therefore better suited to rooftop installations where space is a constraint. Panel efficiency and capacity rating are two important parameters of solar panels.


Inverter determines the quality of AC power you get, and also the kind of loads that can be powered with solar. Different inverters support different levels of starting current requirements, which affects the kind of machinery that can be run on solar power. Inverters are also the only major component of the solar plant that are replaced during the lifetime of the plant.

Mounting structures

Solar panels are mounted on iron fixtures so that these can withstand wind and panel weight. The panels are mounted to face south in the northern hemisphere and north in the southern hemisphere for maximum power tracking. Panels are tilted at an angle equal to the latitude of that location.

Proper design of mounting structures is crucial for the power plant performance as the power output from the PV plant cannot be maximised if the mountings buckle and panels are not optimally oriented towards the sun. In addition, improperly mounted panels present a ragged appearance that is not pleasing to the eye. Mounting structures should also allow sufficient air circulation to cool the PV panels as rooftop PV plant output falls with temperatures rising above 25°C.