𝐓𝐘𝐏𝐄𝐒 𝐎𝐅 𝐒𝐎𝐋𝐀𝐑 𝐒𝐘𝐒𝐓𝐄𝐌𝐒 :
𝐆𝐑𝐈𝐃 𝐈𝐍𝐓𝐄𝐑-𝐓𝐈𝐄𝐃 𝐒𝐘𝐒𝐓𝐄𝐌
A grid inter-tied solar power system is directly connected to the home and to the traditional electric utility grid. Grid inter-tied systems allow the homeowners to get power from either the home electric system or the utility grid. Switching between the residential system and the grid is seamless.
The prime advantage of this type of system is the ability to balance the system production and home power requirements. When a grid inter-tied system is producing more power than the home is consuming, the excess can be sold back to the utility in a practice known as net metering. When the system is not producing sufficient power, the home can draw power from the utility grid.
Grid inter-tied systems are the lowest cost type of residential solar electric system, due to having fewer required components.
Net-Metering has been operational in Pakistan since 2016 through the framework developed by NEPRA (National Electric Power Regulatory Authority), and subsequently implemented by the regional DISCOs (distribution companies) through a one-window operation.
A HYBRID solar power system is also connected to the traditional utility power grid and adds battery-backup to the system. The addition of a battery backup enables the system to balance production and demand and protects against power outages.
Solar electric system production depends on the available sunlight. When sunlight is abundant, production can exceed demand. When production exceeds demand, the excess power can charge the batteries, which store the electricity. When the system is producing less electricity than demanded by the home, the batteries can make up the shortfall.
HYBRID systems are also connected to the utility power grid. This enables the homeowners to draw from the grid during periods of excess demand and to sell power to the grid when there is excess production.
While grid inter-tied systems offer more flexibility, they are not without disadvantages. Charging and discharging batteries reduces the overall efficiency of the system and these systems are more complex to design and install and therefore more expensive.
𝐎𝐅𝐅 𝐆𝐑𝐈𝐃 𝐒𝐘𝐒𝐓𝐄𝐌
An off-grid residential system is for the areas where there is no electricity or short falls. Without a connection to the utility grid, batteries are essential to balance periods of excess production and excess demand.
To protect against shortfalls of power when the solar system is under-producing and the batteries are discharged, System is connected to the grid to just import power for sharing the load. The grid is used as a power source during periods of prolonged excess production or unusual demand.