Solar energy is slowly becoming a huge part of Indian households, and last year’s increased time at home has only cemented its growth. For example, financing in renewable energy projects and the decrease in solar module costs drove the solar prices in the country to an all-time low in 2020. In turn, this has encouraged more people to install solar power systems into their homes, and it is a trend that will likely continue in 2021.
However, there’s more than one type of solar power system available on the market. As an electrical engineer, it’s your job to be familiar with what they are. So below is a brief overview of the three main types.
An on-grid system is the most common type of solar power system available. If the house can’t use all the generated energy, an inverter sends the excess to the public grid. The inverter uses net ties to complete its PCB design. Net ties allow it to convert direct current (DC) into alternating current (AC) — the type of electricity that home appliances and the public grid use — without flagging any violations in the hardware. The public grid then calculates the amount of current it receives and converts it into electricity bill credit.
However, on-grid systems can’t generate electricity during a blackout. After all, blackouts are caused by damages to the public grid. If the inverter still fed power to the grid, it would risk the safety of the people repairing it.
On the other hand, an off-grid system is not connected to the public grid and therefore needs a battery bank to store the excess power. It has two inverters in its layout: the solar inverter and the battery inverter. The solar inverter supplies AC to the property. Meanwhile, the battery inverter is there to catch excess AC not converted by the solar inverter and stores it in a battery bank. Incidentally, having a battery bank means that the homeowner can continue to have electricity during a blackout.
However, since an off-grid system is not connected to the power grid, the homeowner won’t have electricity once their batteries have been depleted. To make an off-grid system work, it needs multiple high-capacity banks in reserve.
A hybrid system is essentially an off-grid system with a failsafe. It still has a battery inverter and battery banks, but it’s also connected to the public grid. Hybrid systems can be built in two ways. The first is to use the battery bank as its main energy source. As long as the battery bank has power, the house will not pull energy from the public grid. The second way is to use the public grid as the main energy source during the day (while the solar panels collect energy), and the battery bank at night. The first is a lot more cost-efficient as it’ll rarely pull energy from the public grid, but the second option is ideal for homeowners that would like the assurance that there will still be power in the battery during a blackout.
Every solar power system needs a different set of components and cable layout. The decision will ultimately be up to your client, however, so it’s important to be familiar will all three.