16 May 2023
Aditya Singhania, Director-Engineering, Navitas Solar
Among all the renewable energy sources, solar PVs have gathered much acknowledgement as it requires less maintenance and the system installation is quite easy. Solar rooftop PV installations are one of the most popular setups used in India nowadays being economical and apt for the space available in the country. India has taken massive target of installing 500 GW of renewable energy out of which 125 GW is already installed including 66 GW of solar. In solar rooftop installation, there are many factors to consider like site evaluation, preliminary design, required load calculation, precise design, installation and cost estimation. In this article, we shall try to understand some of the aspects.
PV SYSTEM DESIGN:
1. Site Evaluation
The site evaluation is the primary step to be followed which enables a PV designer to roughly estimate the electricity requirements for the whole building, whether it is residential, commercial of industrial. It also gives an estimate about rooftop area which is an important factor to design the rooftop solar plant.
The next step of site evaluation is to determine dimensions of the structure of the solar system which can allow a designer to calculate actual shadow free area to maintain reasonable power generation. Next step is to determine optimum location of a solar inverter and distribution box so that DC cable will not be too long as longer DC runs will increase losses. Next step is to find optimum location of net meter for local grid to calculate AC run from the inverter. Generally, a net meter is placed at the ground level of a building, so the site evaluation must incorporate structure height to calculate the length of cables required to travel from the rooftop to the meter.
2. Preliminary Design
After the site evaluation, a PV designer makes a structure in design tool like AutoCAD, Google Sketch up etc to virtually simulate the building and provide a tentative placement of the solar panels considering shadow and other constraints like tilt angle and direction. This provides the approximate number of panels that can be mounted on the rooftop which enables the designer to quote the maximum power output which can be extracted from the panels.
3. Load calculation
This step involves the calculation of the actual load utilized in the building and extracting precise kWh(units) which are essential for the building. This can be calculated by a simple calculation which involves summary of all AC loads utilized in a day, determining peak hours of utilization and duration of utilization of the equipment. Normally, estimation of the typical load is achieved by using electricity bills of the building. For easy calculation, output watts of an equipment are multiplied by no. of hours which gives watt hour or a unit. For example, an AC utilizes 1500 W of power and it runs approximately for 6 hours a day, so the unit will be 1500*6=9000 wh=9 kwh/units. Similarly, the load calculation is done for the whole building with every connected load.
After the load calculation, a simulation is run to determine the rough estimate of no. of panels, strings required as well as cost estimation. PVsyst, Helioscope, SAM are some of the well-known tools for this.
4. Design
In this step, the process designer designs the whole set up. Drawing with actual dimensions, optimum placement of panels keeping in mind the shadows and space available, calculation of the number of strings in an array, determining the size of inverter with net meter and distribution box, AC cables and DC cables etc.
5. Cost Estimation
For any energy generation plant, each equipment has their own cost and per unit of electricity generation is kept in mind for targeting the profit. Costing of the system includes cost of panels, inverter, mounting structure, cables, distribution boxes, installation etc. Degradation factor is also considered to calculate total number of units generated over 25 years and from that cost of unit of electricity generated is computed.
It is evident that Rooftop solar system is one of the best methods of power generation systems to exist in this era considering cost analysis. The cost is fairly cheaper compared to electricity produced by non-renewable sources. The way solar PV system is adapted in metro cities as well as tier-2 Tier-3 cities nowadays is commendable. Awareness among the consumers play a huge role. As an energy consumer, it is very important of us to be familiarized to this technology so that we can leap forward to a greener world. Navitas Solar, a leading module manufacturing company provides best Solar EPC services. Renowned Solar provider Navitas Solar considers all the factors while designing a solar power plant. With Navitas Solar, it will be easy for the solar seekers in India to move forward in adopting green energy, contributing to the National Solar Mission.
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