What kind of a solar power system should I install for my home? Should I install a system with batteries or without batteries?

As a home-owner a key decision you need to make when going solar is to decide whether you should opt for a system with batteries (hybrid solar system) or without batteries (grid-tied solar system). The table below provides a brief comparison of the two types of systems and their relative benefits:

Comparison: Hybrid solar power system vs Grid-tied solar power system

Reduction in Electricity Bill

In case of a hybrid solar power system, the electricity bill savings are as a result of grid power consumption being substituted by solar power. Grid power is only consumed when the solar power is insufficient to power the loads connected to the solar inverter. In case of a grid-tied solar power system, the electricity bill savings are mostly due to the electricity bill being adjusted to the extent of the solar units exported to the grid and you are only charged for the net units consumed from the grid. Thus the utility grid acts as a virtual reservoir of the solar energy being exported by your home and your entire consumption is adjusted against this. This adjustment normally takes place under a net metering policy &continued savings from a grid-tied solar power system is dependent on effective implementation of the same.

Back-up power during grid outages

The storage battery bank in a hybrid solar power system is sized to provide the necessary back-up to connected loads during a grid outage. In case of a grid-tied solar power system, technical reasons &safety regulations mandate that the system shuts down during a power outage (a feature known as anti-islanding), so, your home will be without power even though the solar panels on your roof are capable of producing power.

Approvals required from Utility Company

There are no approvals required from the Utility or Distribution Company (DISCOM) for installing a hybrid solar power system. Approval is only required where the system is designed with a bi-directional solar hybrid inverter with grid-export feature.

All grid-tied solar power systems require the installation of a bi-directional energy meter & approval from the Utility Company. This often increases both the cost & the time required for such systems to be operational as the paperwork & understanding of the local representatives of the Utility Company varies from place to place.

Utilization of solar energy

In case of a grid-tied solar power system, if there is a power cut during sunshine hours i.e. when the solar panels are generating energy, the energy would be un-utilized as the gird-tied inverter shuts off the solar system (anti-islanding mode) resulting in a lower return on your investment in the solar panels.

A well-designed solar hybrid system ensures the solar capacity; inverter capacity & the battery storage capacity are optimized to ensure maximum utilization of the energy generated by the solar panels. In addition, a hybrid system is able to utilize the solar energy generated, either to supply loads or charge the battery independent of grid power availability.

Appliances utilizing solar energy

In case of a grid-tied system, solar energy is fed into the mains of the distribution board & will be utilized by all the loads that are running at that time.  As a result this is the simplest & lowest cost system to install as there is no separate internal wiring/changes required to distribute the solar power internally.

Because a hybrid solar power system also doubles up as a source of back-up power it is required to separate the loads that will consume back-up power onto a separate wiring circuit – These loads are typically called “connected loads”, or, “essential loads”.