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What Is A Bimodal Solar System And How Does It Work? | Solar Energy USA Blog Archive

What Is A Bimodal Solar System And How Does It Work?

Posted on Thursday, June 16th, 2011 at 2:47 pm by Solar Energy USA

Cumming, Georgia residential bimodal solar installation:

A bimodal solar system is a PV system that can operate in either grid-connected or stand-alone mode, and uses battery storage. The key difference in the bimodal system is the inverter setup, which draws DC power from the battery system instead of from the solar array. In the case of a bimodal system, the array simply acts as a charging source for the battery system. The main goal of a bimodal solar system is to charge the battery bank with solar power from the sun and store it as an emergency source of power. Power is drawn from the batteries, inverted to AC, and then sent to power your home’s loads. Excess energy is sent back to the power company via the grid.

Bimodal system components and layout

Should the utility grid have an issue causing it to go down, a transfer switch automatically disconnects the bimodal solar array from the utility and tells the inverter to supply AC power sourced from the battery bank.

The massive bimodal inverter which converts DC power from the sun into AC (usable household form)

Bimodal solar systems are popular for homeowners and businesses where a back-up power supply is required for critical loads such as computers, refrigerators, water pumps, or lighting when a utility power outage occurs. With a bimodal system, the AC power from the inverter is routed to an isolated subpanel that serves only the critical loads.

Critical panel for critical loads

The ability of these systems to provide back-up power is a significant and main advantage over standard grid-connected systems, despite the extra costs (which come mainly from the batteries).

Battery bank showing some of the 40 batteries that will be used in this 7.36kW bimodal solar system

Back view - Cumming, Georgia 7.36kW bimodal solar roof installation

This particular Georgia homeowner wanted a 7.36kW bimodal system connected to specific critical loads (a refrigerator, an A/C unit, a computer, a few lights, and a freezer). A total of 32 solar panels were used along with 40 batteries for emergency storage.

As you can see from this recent residential solar install, a bimodal system is one of the most complex of all solar designs.

To learn more about solar please see our Solar 101 page or contact us for a free consultation.