Going off the grid | Two ways to keep Wi-Fi on during load-shedding

WITH an energy expert agreeing that load-shedding is here to stay for the next few years, we need to find a way to keep connected. Many homeowners are turning to technological solutions to keep their Wi-Fi up and running when the lights go out.

Among the technological solutions to these power-outage problems are devices like the inverter and UPS (uninterrupted power supply).

To find out more about these devices, Berea Mail contacted Dr Katleho Moloi, an energy expert and acting HOD for the Department of Electrical Power Engineering at the Durban University of Technology.

What is an inverter?
As the name suggests, this device works to invert the power supply stored in a battery to run appliances that are usually plugged in and powered by electricity. It is important to note from the outset that power stored in a battery is stored as direct current (DC) while electrical power is alternating current (AC).

“In simple terms, an inverter is a device that converts direct current (DC) to alternating current (AC),” explained Moloi.

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Inverters typically work in conjunction with solar panels or batteries.

“The energy we get from the sun is DC, and all home appliances use alternating current, so we cannot power these appliances with a DC source. An inverter is a compact device – there are a lot of components inside which convert DC to AC, including capacitors, diodes and switches. This is necessary because you can only store power in DC form – you can’t store the electricity supplied by Eskom because it is AC,” said Moloi.

Home Wi-Fi is also powered by AC, which means that power stored in DC form must be inverted to keep Wi-Fi devices working during load-shedding – although fibre connections present some challenges.
“Fibre connection will be difficult to supply with an inverter device because the fibre link (outside the home) is powered by AC. That is why cellphone reception and internet connectivity are weaker when there is load-shedding where the tower is located – because towers use AC. They have some backup power supply in a DC battery, but when the battery depletes, connectivity is lost,” said Moloi.

Inverter prices in a nutshell 

• Inverters range in price. An inverter is typically priced in the R2000 range while batteries are around R3000 each. An inverter that delivers 720W should keep laptops and Wi-Fi running or keep a TV and streaming service operational. This is priced in the R9 000 – 10 000.

What is a UPS?

A UPS (uninterrupted power supply) utilises multiple backup power sources to ensure the power supply is not broken.
“This is utilised when designing systems for a hospital, for example, where there is a critical load and the power supply cannot be interrupted. With UPS, if you lose the main line – you have other power sources available – such as solar or wind power, and a generator – just as there are multiple streams or rivers carrying water into the ocean – UPS cannot have a single power source,” explained Moloi.

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A UPS is a compact device which may include a solar panel and inverter.
“UPS is a very good option for someone with a fibre connection because UPS has multi-connection points with AC or DC options. The current design gives you flexibility, whereas an inverter does one thing – convert DC to AC,” said Moloi.

UPS costs in a nutshell

A UPS with a 12-volt 100 AH battery is priced in the R9 000 range. A 1KVA device (with about 800W capacity), using a lead acid battery, is priced in the R6 000 range. A similar device using lithium batteries is priced in the R10 000 range, and these batteries would recharge faster. To power a TV, average laptop and Wi-Fi for a few hours, a 600W device should be sufficient, although UPS devices can range from about R3 000 for a device with a 500W capacity. The energy needed would depend on the type of devices being powered as laptops and TVs differ in energy consumption.

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