Solar powered outlet: three ways to get power outdoors without running a cable

People search for a solar powered outlet for all sorts of reasons: a socket by the patio, power in a shed with no cable to it, a pump for a pond, somewhere to charge tools at an allotment. The answer is the same in each case. You need something that collects energy in the day, stores it, and turns it back into mains power when you plug something in. There are three ways to get that.

Three ways to do it

1. A portable power station with a solar panel. This is the simplest by far. The power station is the battery and the inverter in one box, with outlets on the front. You connect a folding or rigid panel to its solar input and plug things in. There’s no wiring to do, and you can carry it indoors for the winter or use it as backup in a power cut. Popular 1 kWh models include the Jackery Explorer 1000 v2 ($589 list, on sale at $509 when we checked), the Anker SOLIX C1000 Gen 2 ($699.99) and the EcoFlow DELTA 3 Plus ($799 list, $719 on sale). Makers also sell them in bundles with panels, often called solar generators. Our guide to solar generators for the home compares them.

2. A fixed off-grid system. For a shed, workshop or cabin you use often, panels on the roof feed a charge controller, a battery bank (usually 12 V or 24 V lithium iron phosphate) and an inverter, with outlets in weatherproof boxes. It takes more planning than a power station, but it’s permanent and can grow with you. It’s also proper electrical work. Check whether your local rules need a permit or a registered electrician, especially for anything wired into a building.

3. Small DC setups. For lights, phone charging or a small pump, you may not need mains power at all. Solar USB power banks, 12 V lights and solar fountain pumps skip the inverter, so less energy is wasted, and they’re much cheaper.

What a solar outlet is not is a panel plugged into an outlet on your house. That’s plug-in solar. It feeds your home’s wiring, it doesn’t give you a separate socket, it switches off when the grid goes down, and it’s only allowed with certified kits where the law permits it.

How much will you use?

Add up what you’ll plug in. These are typical figures; the label on each device gives the real wattage.

Two numbers come out of this: the energy you need each day, and the most power you’ll draw at once. The second one sets the inverter size. A power station rated at 1,500 W can’t run a 1,800 W saw, however full its battery.

How much panel do you need?

This depends on where you live and when you want it to work. We ran the European Commission’s PVGIS model for 100 W of panel tilted at 35° toward the south. The figures are the average energy per day in each month.

PVGIS 5.3, 100 W of panel, 14% system losses. A panel laid flat, propped at a poor angle or partly shaded makes less.

The method is simple. Divide your daily energy by the figure for your worst month, multiply by 100, then add about 15% for the losses in charging and discharging the battery.

Example: a shed in London using 0.3 kWh a day.

• For summer use only: 0.3 ÷ 0.41 × 100 = 73 W, plus 15%, so a 100 W panel.
• All year: 0.3 ÷ 0.12 × 100 = 250 W, plus 15%, so about 300 W of panels.

The same shed in Baltimore, all year: 0.3 ÷ 0.29 × 100 = 103 W, plus 15%, so about 120 W. A 150 W panel gives some margin.

The gap between summer and winter is much smaller in the US than in Britain. In London, a year-round setup needs about three times the panel of a summer-only one, and in Manchester about four times.

How big a battery?

The battery covers the night and the days when it’s too cloudy to recharge. The US Department of Energy’s guidance for off-grid systems says battery banks are typically sized to cover one to three days of use.

battery size (Wh) = daily use (Wh) × days to cover ÷ 0.85

The 0.85 allows for inverter losses, as in our other calculators. For the shed using 0.3 kWh a day and two days of cover: 300 × 2 ÷ 0.85 = about 700 Wh, so a 1 kWh power station is plenty. A garage freezer at 0.8 kWh a day for two days needs about 1.9 kWh, a 2 kWh unit. Our battery size calculator does this for you, and you can add your own appliances.

Keeping it safe

• Protect mains outlets outdoors. In the US, outdoor outlets on a house have needed GFCI protection for decades, according to the Consumer Product Safety Commission. In the UK, Electrical Safety First advises using an RCD with all outdoor electrical equipment, and a plug-in RCD if your fuse box doesn’t have one. Apply the same standard to a solar outlet.
• Keep power stations dry and shaded. Most aren’t waterproof. Put the box under cover, out of direct sun, and run only the panel cable outside.
• Mind the cold. Lithium batteries shouldn’t be charged below freezing unless they have a built-in heater. If the station sits in an unheated shed, check its charging temperature range.
• Use outdoor-rated cables, and don’t run them through doors or windows where they can be pinched.
• Never connect a solar setup to your house wiring without a proper transfer switch or inlet fitted by an electrician. Feeding power back into the wiring can endanger anyone working on the lines.

Which one should you choose?

• Occasional use, or you also want backup for power cuts: a power station and a folding panel.
• A shed or workshop you use every week: a fixed system, or a power station that stays in the shed with a rigid panel on the roof.
• Lights, phones or a fountain: small DC kits. They’re cheaper and waste less energy.

For specific models at each size, see our best portable power stations.