Solar System Types

Grid-tied solar systems

Grid-tied, on-grid, utility-interactive, grid intertie, and grid backfeeding are all terms used to describe the same concept – a solar system that is connected to the Utility power grid.

Grid-Tied Solar System is signified by the absence of battery backup. There is no battery involved and in case of Power Grid outage or load shedding, there is no power supply from solar panels.

The obvious advantage is that such system does not involve any repeated expenditure on expensive batteries. Such Grid ties solar systems are best in areas where there is very less no load shedding at all.

In Pakistan, such areas exist in affluent areas under DESCOs where electricity is constantly supplied and there is very less load shedding and in private societies like Behria Town, DHA and other private housing societies and buildings that have their own power generation units.

Off-Grid solar systems

Off-Grid Solar system is defined as a solar system that is completely disconnected from the Utility power grid.

Off-Grid Solar System is signified by the presence of battery backup. Number of batteries is calculated on the basis of daily power usage of all or essential power devices present in the system.

The solar plates generate the power during the daytime and batteries take over at sundown.

The system is installed in remote areas or where there is no power grid nearby as well as in cases where the customer needs to isolate some of the load from the available power grid.

Hybrid solar systems

Hybrid solar systems combine the best of grid-tied and off-grid solar systems. These systems can either be described as off-grid solar with utility backup power, or grid-tied solar with extra battery storage.

If you own a grid-tied solar system and drive a vehicle that runs on electricity, you already kind of have a hybrid setup. The electrical vehicle is really just a battery with wheels.

In a hybrid solar system, energy generated from the solar panels is first used to service the home’s electrical loads (flow #1).

After the home’s energy needs have been supplied, solar power is used to charge the solar battery (flow #2).

If there is still a surplus of solar energy, it will be exported to the electric grid in return for credits (flow #3).

The system pictured above shows an AC-coupled lithium battery, but hybrid systems can also be designed using either lithium, dry or lead-acid-based DC batteries.

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