Solar PV system sizing is an important part of the solar installation process. The correct size of your system is necessary to maximize energy performance. Now that you are familiar with On-grid and Off-grid Solar PV System, let us see how on-grid and off-grid connection affect the size of your solar PV system.
The off-grid connection has many disadvantages concerning the cost and efficiency of your system. Among the list of disadvantages of off-grid systems is that your electrical appliances are directly connected to the solar PV system. This means more worries when it comes to figuring out the size of your system. To calculate the right size of the system, you will have to consider the daily usage, appliance wattage and all that will lead to a series of confusing and complicated mathematics.
On-grid connection, on the other hand, adds the ease of calculating the size of your PV system to the list of many advantages. All that you require for estimating the size of your system with the on-grid connection is your electricity bill and a keen eye for detail. Your electricity bill has a value called ‘Sanctioned Load’ or ‘Connected Load’ whose 100-150% system equivalence is acceptable for installing Solar PV system. For example, if your sanctioned load is 10 kW, then in certain places you will be permitted to install a maximum of 10 kW solar plant whereas in some places you can extend the size up to 15 kW. This is highly dependent on the state’s policy and exceeding 150% of the connected load is not acceptable for the on-grid system.
Now that you have understood the role of grid-connectivity on determining the size of the system, you are just one step away from finalizing your system size.
Shadow analysis is the last and the final step of deciding the size of your system. To ensure optimum output from your Solar PV system, you should have ample shadow-free area to hold the system. A shadow-free area of 90-100 sq ft for 1 kW solar panels facing 15-18 degree south (depending on the city) is the right space and direction. Shadow analysis is the right way by which you can avoid hindrance from nearby buildings, trees etc. and get ample sunshine by setting the panels in the right position and angle. Using shadow analysis you can also estimate the maximum space that can be utilized and the maximum size of your system. Although you may have to pay upfront for the analysis, it has huge benefits if rightly done for decades to come.