Importance of Module Mounting Structure in a Solar Rooftop System

With the beginning of slow but gradual phasing out of Fossil Fuels from our energy ecosystem, the Renewable Energy sources in a short span of time have gained tremendous popularity. Solar PV plants as distributed energy sources have changed the way people used to think about the power generation. Solar PV as ground mounted system have largely come up in rural or remote areas where land prices are higher. But the Solar Rooftop system has steadily gained popularity in urban areas as no or little investment on land purchase/lease is required.

With solar rooftop systems becoming popular, there is a need to give due importance to the non core segments of solar PV systems like Module Mounting Structure(MMS) and other Balance of Systems(BoS) in the same way as PV modules and Invertors have gained traction. The module mounting structure is one area which gets neglected a lot. While the importance is given to modules, invertors, cables and other electrical and electronic items, the quality of MMS is always a casualty in the price cutting decisions.

A sturdy and weather resistant structure is of equal importance to other systems in a solar rooftop if not more. The price of MMS varies significantly based on the type of roof, orientation and the weather conditions where the system is to be installed. The price range of MMS is Rs 2.5 to 4.5 per Watt. The importance of MMS for a Solar Rooftop system can be gauged from the fact that a sturdy MMS ensures the proper tilt angle. Generally the structures are placed in a way to have a tilt angle of 20 deg. But with solar PV calculators, the tilt angles giving the maximum output can be worked out.

Solar Rooftop
Solar Module Mounting Structure

If we take an example of a city Hyderabad ( Lat, Lon: 17.35, 78.45). The AC annual energy output for a 18 kW 20 deg tilted system would be about 27962 kWH while for 5 deg tilted system it would be 27185 kWH. A drop of about 3%. So if one doesn’t want to invest in a sturdy system to have a tilt angle of 20 deg, the solar array can be placed as close as to the roof surface, sacrificing on the efficiency but at the same time saving on the MMS. The chances of wind blowing the system will also get reduced if the solar rooftop system is placed close to the roof surface with hardly any gap between the rooftop and lower surface of the array. In case of inclined tiled roofs, the options on tilt angles are limited. The MMS has to be placed in line with the roof’s inclined surface.

Tilt angle plays an important role in determining the efficiency in case of fixed array solar rooftop system but at the same time giving too much of an importance to the system tilt angle and thus spending more on the MMS broadly seem counterproductive. So my advice would be to work out your costing with tilt angles, MMS and energy output combinations and then take decisions wisely.

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