Solar backup for home offices and online classes

For most households a power cut is an inconvenience. For someone working from home, or a child in an online class, it can mean a dropped meeting or a missed lesson. The good news is that keeping a work corner running takes far less power than most people expect, because the things that matter, a laptop, the Wi-Fi and a light, use very little. This guide shows how to work out what you need, and when rooftop solar with a battery is the right answer.

What a work corner actually uses

These are typical ratings for common equipment. Your own figures are on each device’s label or charger.

So a laptop, the router, one light and an ordinary fan come to roughly 120 to 170 watts. Two laptops for a parent and a child add another 50 or so. An air conditioner, at 1,200 watts or more, is a different matter, and is usually left off the backup circuit.

How much battery you need

The same rule of thumb we use for any backup applies:

Battery size (kWh) ≈ watts on backup × hours of backup ÷ 1,000, plus about 20% margin.

A small battery covers a lot of work. For comparison, the usable energy of a common home-inverter bank of two 150 Ah tubular batteries is a little under 2 kWh, and a 5 kWh lithium battery gives about 4 to 4.5 kWh. Our guide to how long a solar battery lasts in a power cut works through more examples.

Three ways to keep working

1. Your existing home inverter. If you already have one, check that the work corner’s sockets, light and fan are on its backed-up circuit, and that the batteries are healthy. For many homes, that alone covers a normal cut.

2. A small UPS for the router. A home inverter takes a moment to switch over when the supply fails. A laptop on its own battery does not notice, but a router or desktop computer can restart, and a video call drops while the Wi-Fi reconnects. A small UPS on the router and modem avoids that.

3. Rooftop solar with a battery. A hybrid solar system cuts the electricity bill through net metering, and during a daytime cut the panels keep charging the battery and running the backed-up circuits. This is the option for homes with long or frequent cuts in working hours, or where the old inverter’s batteries are due for replacement anyway. Our guide to connecting solar to an existing home inverter compares it with keeping the inverter you have.

Practical tips

• Put only what matters on backup: the work sockets, the Wi-Fi, a light and a fan. Leave geysers, irons and air conditioners off it.
• Keep the router on the backup circuit, not on an ordinary socket. It is the most common thing people forget.
• Charge laptops fully before expected cuts, and keep a phone hotspot as a fallback for the internet itself, which can fail when the cut reaches the provider’s equipment.
• Choose a BLDC fan for the work room. It uses about half the power of an ordinary fan, which doubles the time the same battery lasts for that load.
• Test the backup once a month, by switching off the main supply for a few minutes in working hours.

How we size it

We ask what you need to keep running, for how long and at what time of day your cuts usually come, then size the battery and choose between keeping your inverter and a hybrid system. Lithium or tubular is a separate choice, compared in our guide to lithium or tubular batteries. Our battery backup page has the details of hybrid systems.

Common questions

How big a battery do I need for work from home?

For one laptop, the Wi-Fi, a light and a fan, about 150 watts, a battery of about 0.5 kWh covers three hours and about 1.1 kWh covers six. Add about 50 watts for each extra laptop, and work it out with watts × hours ÷ 1,000, plus 20% margin.

Will my Wi-Fi stay on during a power cut?

Only if the router is on a backed-up circuit or a small UPS. Even then, the internet can fail if the cut also reaches your provider's equipment in the area, so keep a phone hotspot as a fallback.

Is a home inverter enough for online classes?

Often, yes, if the laptop, the router, a light and a fan are on its backed-up circuit and the batteries are healthy. A router can restart when the inverter switches over, so a small UPS on the router keeps a class from dropping.

Does solar keep working in a power cut?

An ordinary on-grid system does not; it must switch off when the grid fails. A hybrid system with a battery keeps the backed-up circuits running, and during the day its panels keep charging the battery.