Quick Answer
A Hybrid System can work with a small battery bank, but careful consideration must be given to the size and configuration of the system, as well as the critical loads that need to be supported.
System Configuration and Battery Size
A hybrid solar system typically consists of a grid-tie inverter, a critical loads panel, and a battery bank. While a small battery bank can be used, it’s essential to size the system correctly to ensure that the battery bank can provide enough reserve capacity to support critical loads during grid outages or periods of low solar irradiance. For example, a 3.6 kW grid-tie inverter with a 3.6 kWh battery bank may be suitable for a small residential home with minimal critical loads.
Islanding and Transfer Switching
When the grid is lost, the hybrid system must be able to transition to island mode and automatically switch to battery power without causing a blackout. This requires a transfer switch and an islanding inverter that can rapidly transition between grid-tie and island mode. The transfer switch should be designed to handle the voltage and current surges associated with the transition.
Critical Loads Panel and Battery Sizing
The critical loads panel should be designed to prioritize the most critical loads, such as lights, refrigerator, and medical equipment. The battery bank size should be determined based on the maximum demand of the critical loads and the desired backup duration. For example, a 3.6 kWh battery bank may be sufficient to support a 1 kW critical load for 3-4 hours during a grid outage. To determine the correct battery bank size, calculate the maximum demand of the critical loads and use a 3:1 to 5:1 discharge reserve requirement to determine the required battery capacity.
Find more answers
Browse the full Q&A library by topic, or jump back to the topic this question belongs to.