Hybrid Solar for Commercial Buildings: Keeping Key Loads On

For many businesses a power cut means lost sales, stopped work or lost data, not only darkness. A hybrid solar system adds batteries to the panels and the utility connection so that the essential loads keep running when the supply fails.

The key to a good design is to decide first which loads are essential, and then size the battery and the inverter for those.

Key takeaways

• A hybrid system keeps chosen loads on through a power cut and still lowers the utility bill.
• Essential loads are put on a separate backup board.
• Battery size follows from the essential load and the hours it must run.
• A generator can still be part of the plan for long outages.

Choosing the essential loads

Walk through the building and ask what must not stop. In a shop it may be the till, the card machine, the lights and the CCTV. In an office it may be the computers, the network and a few lights. In a showroom or clinic it may include refrigeration or small medical devices.

• Point-of-sale and card machines.
• Servers, network equipment and computers.
• Lighting for safety and work areas.
• CCTV and alarms.
• Refrigeration for stock that spoils.

How the system is arranged

The hybrid inverter feeds a backup distribution board with the essential loads. In normal times the panels and the utility supply the whole building and charge the battery. When the utility fails, the inverter isolates the building from the grid and runs the backup board from the battery and the panels.

Sizing the battery and the inverter

Add the power of the essential loads to find the inverter size, and multiply by the hours of backup you want to find the energy the battery must supply. The battery must have more rated capacity than that, because only part of it is usable. Air conditioners and large motors start with a high current, so they need a larger inverter, or they are left off the backup board.

Hybrid with a generator

Where outages are long, a generator can supply the building while the batteries are kept for the short breaks and for the time the generator takes to start. Mixing the two needs a proper changeover arrangement, which we design with the system.

When to call us

We can list your essential loads, size the battery and the inverter and quote the complete system. Use the quote page, read about commercial solar, or see the batteries and inverters we supply.