Inverters and batteries for shops: sizing for power cuts

For many shops and small offices, a power cut means lost sales — the billing machine stops, lights go off and customers leave. An inverter with the right batteries keeps essentials running. The key is sizing it for what you actually need, not guessing.

List what must keep running

Walk through the premises and list only the essentials during a power cut:

• Lights and fans
• Billing computer, printer and card machine
• Internet router and CCTV recorder
• Any freezer or display fridge that must stay on

Note the wattage of each item (it is usually on the label or in the manual). Items with motors — fridges, pumps, some coolers — draw extra power when they start, which matters for sizing.

Inverter capacity: how much load at once

Inverter capacity is usually stated in VA. It decides how much load can run at the same time.

• Add up the wattage of everything that will run together.
• Leave a margin rather than running the inverter at its limit.

Air conditioners usually need a much larger system; if you want an AC on backup, tell the supplier upfront.

Battery backup: how long it lasts

Battery capacity (in Ah) and the number of batteries decide how long the backup lasts.

• More load means shorter backup.
• Tell the supplier your typical power-cut duration in your area, so they can suggest capacity.

Choosing batteries

• Tubular batteries are common for long power cuts and last well with basic care.
• Flat-plate batteries are usually cheaper but may not last as long under heavy use.
• Lithium batteries need little maintenance and are compact; ask about their warranty and compatibility with your inverter.

For lead-acid batteries, ask about water topping and keep them in a ventilated place.

Sine wave matters for electronics

Ask whether the inverter gives a pure sine wave output. Computers, printers and some appliances run better and quieter on it.

Installation, safety and warranty

1. Ask for proper wiring so only essential circuits run on backup.
2. Place the system in a ventilated, dry spot, away from where customers walk.
3. Ask separately about warranty on the inverter and the batteries — they differ.
4. Ask whether the supplier offers service visits.

Mistakes to avoid

• Adding extra appliances later. Plugging a heater or a larger cooler into an inverter sized for lights and computers overloads it.
• Mixing old and new batteries. In a battery bank, a weak old battery drags down new ones. Replace them together.
• Keeping batteries in a closed, hot corner. Heat shortens battery life; ventilation matters.

What to include in your enquiry

• List of appliances to run on backup with wattage
• Typical power-cut duration and how often cuts happen
• Battery preference (tubular, flat-plate, lithium) or ask for advice
• Whether installation and separate wiring are needed
• Your location and required date

Compare suppliers in inverters, UPS and batteries, or post your requirement with your load list.