Solar, battery backup and UPS: choosing the right combination for your workplace

A twelve-person office loses power. The laptops stay on, but the Wi-Fi router and the small server holding shared files switch off. Staff can’t open those files or send email.

The next morning, staff offer three suggestions: “We need solar.” “Get a UPS.” “Buy a battery inverter.”

Each could help, but they do different jobs. Knowing the difference makes it easier to choose what the office needs.

What each part does

• Generate

  Solar panels

  Turn sunlight into electricity. They produce less electricity on cloudy days and none at night.

• Store

  Battery

  Holds energy for later. It has to be charged, and it needs time to recharge after use.

• Convert

  Inverter

  Turns electricity from panels or a battery into the form used by office equipment.

• Cover the gap

  UPS

  Uses its own battery and inverter to keep connected equipment running when power goes off.

Solar panels are also called PV panels. PV is short for photovoltaic: turning sunlight into electricity. A battery stores energy from solar, the mains or another source for later use.

Panels and batteries supply direct current (DC), which flows in one direction. Mains sockets supply alternating current (AC), which changes direction. An inverter changes DC into AC for office equipment.

A UPS, or uninterruptible power supply, can keep equipment running for a short time when the power goes off, giving staff time to save their work and shut down safely. How long it lasts depends on the UPS and the equipment connected to it. If the office’s battery backup already keeps those devices running, it doesn’t need a separate UPS for the same job.

Will solar panels keep the office running when power goes off?

Having solar panels on the roof doesn’t always mean the lights and computers will stay on when power goes off. The system needs to be set up to supply the office when there’s no power from the mains. At night, the panels produce no electricity, so the office needs a battery with enough stored energy to keep the chosen equipment running. Cloudy weather can also mean less solar power is available to recharge it.

You can also have battery backup without solar panels. The battery charges from the mains while power is available, then supplies the office when power goes off. With a suitable inverter, either setup can take over quickly enough to keep computers and network equipment running without a separate UPS.

Power and energy: what’s the difference?

Power, measured in watts (W) or kilowatts (kW), is how much electricity equipment uses at once. Energy, measured in watt-hours (Wh) or kilowatt-hours (kWh), is how much is used or stored over time. Picture a water tank: power is how fast water flows out; energy is how much the tank holds.

The inverter or UPS must be able to power all the connected devices at once. The battery needs enough energy to keep them running for the time needed. How fully charged it is and its condition also matter. The system uses some energy itself, so the power rating alone won’t tell you how many hours the backup will last.

When backup power takes over

A suitable battery backup system can take over so quickly that computers, routers and servers stay on when mains power goes off. In that case, a separate UPS isn’t needed to keep them running.

Some systems leave a brief gap before battery power takes over. If that gap makes equipment restart, a suitable UPS may help. It can also keep equipment running while a backup generator starts.

The installer checks that the backup can supply enough power and take over quickly enough for the equipment connected to it.

Three options to discuss

The manager could discuss these options with an installer.

• Choice A

  UPS for essential equipment

  Main job

  A suitable UPS keeps equipment running for a short time when power goes off, giving staff time to save work and shut down safely.

  In this office

  The Wi-Fi router and the small server.

  Worth asking

  How long will it keep the equipment running? Will any devices restart as it switches to battery?

• Choice B

  Battery and inverter backup for selected equipment

  Main job

  Keeps selected devices running for the time the system is sized to cover.

  Charged by

  The mains, when it’s available. No solar needed.

  Worth asking

  Which devices will it power, and for how long? Will they stay on as the backup takes over? How quickly can the battery recharge?

• Choice C

  Solar panels with battery backup

  Main job

  Panels generate electricity by day and a battery stores energy for later. A suitable inverter can keep equipment running when mains power goes off.

  Depends on

  Enough sunlight to charge the battery, enough stored energy, and a system set up to supply the office when mains power goes off.

  Worth asking

  Will the connected equipment stay on when power goes off? How long will the battery keep it running?

When a small change may be enough

If the office has no battery backup and staff only need time to save files and shut down, a suitable UPS for the router and server may be enough. The laptops already have their own batteries. If an existing battery backup keeps everything needed running, there’s no need to add a separate UPS for the same job.

Keeping those files available for several hours needs more stored energy. Battery backup, with or without solar, could help. Our article on what should stay running during an outage explains how to decide which equipment matters.

What an assessment looks at

An assessment checks what needs power, how much it uses, how long the power stays off and how quickly the battery can recharge. It also checks whether devices stay on as the backup takes over and, if solar is wanted, space and sunlight for panels.

You don’t need to design the system. Tell us what stops working and how long the power usually stays off. Read about our solar and backup power service, or get in touch to talk about your workplace.