Running a Small Office with an Inverter [12V Power in a Box Hybrid Inverter]

By Neil Vorster

generators, home off the grid, inverters, loadshedding, Office off the Grid, ups, UPS Inverters

Power Requirements and Inverter Solution

Running a small office without interruption of your telephones and internet connectivity during loadshedding events using the Hybrid Power in a Box Uninterruptable Power supply Inverter.

Office Reception Requirements

To establish your requirements we start with a load audit.

How much power do you need and for how long?

1 PC  - 50Watts

1  WIFI router – 7 Watts

1  Fibre internet box – 10 Watts

1 Cellphone charger – 7 Watts

Inverter fan – 30 Watt

Total requirement is 104  W

Capacity : Power in a Box –Small office and student model  12V UPS, 1200VA 

The 12 V Battery has a capacity of 80Ah ( 80 Amp Hours) , but being a deep cycle lead acid battery, you don’t want to use more than 50% of the battery’s capacity to ensure a long battery life.

Therefore you only have 40 Ah available in your 12 V Battery  40 X 12 = 480 Wh ( Watt Hours)

For 2 hours of backup you can therefore run 480/2 = 240 Watts.

For 4 hours of Backup you can run 480/4 = 120 Watts.

Your office reception uses less than 120 Watts, so the Power in a Box can cope with 4 hour loadshedding events.

Solar addition

If you want to be able to remain running with blackouts lasting a day or more, we recommend adding a single 200W solar panel to your Hybrid UPS inverter. (Simply put the solar panel facing full sun, and plug it in to the power points provided on the Inverter)

A 200W panel will give you 200 W for about 5 or 6 hours on a sunny day. While the sun is shining, your panel will run your load (of approx. 100W ) while charging your battery. After sundown, you will have 4 more hours of backup on the battery.

The system is designed for extreme flexibility  to take up to 700W of solar power in multiple panels if required, and extra batteries can be added to increase your electrical load and storage capacity.

Phase 2  

Office/Training room / sales room requirements

10 laptops (40 - 50 W each) = 400 - 500 W

Inverter fan 30 W

Total requirement = 430 – 530 W

Capacity : Power in a Box –Small office model 24V UPS, 2400 VA model 

The 2 X 12 V  Batteries = a 24 V battery with a capacity of 80Ah.

Therefore you only have 40 Ah available in your 24 V Battery 40 X 24 = 960  Wh

For 2 hours of backup you can therefore run 960/2 = 480 Watts. Ie 10 Laptops for 2 hours

For 4 hours of Backup you can run 960/4 = 240 Watts.  Ie 5 laptops for 4 hours

Solar Addition

2 Solar panels of up to 350 W each ( 700 W total )  can be added to supply more than the 480 W required to run 10 laptops while recharging  your batteries.

Power in a Box Prices  - March 2023 

Power in a Box – Home office and student  12V UPS, 1200VA   R5 999

Power in a Box – Small office model 24V UPS, 2400 VA  R8 999

200W solar panel R3 000

This video provids an Introduction to small office Power in a Box an dincludes the elementary calculations required to size your unit.


About the author

Property Investment Coach
Off The Grid Power consultant
BSc Eng - (Wits) 1985

Neil Vorster

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