Best solar chargers 2021

Keep your battery topped up with these solar chargers

Many of us are using our cars less these days but are relying on the battery to power devices which keep running even when the car is switched off, such as alarms, trackers and dash cams with parking modes. Even a clock could drain enough power over time to mean you hear the dreaded click when you try to start the engine.

In an ideal world we’d all keep our cars topped up using a mains-powered battery charger, but in reality not all of us have access to a plug. 

The solution could be to use the sun to keep your battery in tip-top condition with a solar-powered charger. Place one in the windscreen and it could ensure you always have enough juice to keep your gadgets running and still churn the starter motor when you turn the key.

Which of our eight chargers puts the others in the shade?

How we tested them

The price of these solar chargers varies hugely, so we scored them on their performance in variable light conditions by measuring the output to a partially discharged 12V car battery. We also gave points for the ease of connection and features that ensured the battery was not overcharged. We also checked to ensure that they wouldn’t actually drain the battery when it was dark. Finally, we took the price into account using the best online sources. 

Top tips

Before you buy a solar charger, work out what is the  best for your situation and vehicle. If you want to keep the panel and wiring inside the car you’ll need to make sure you have a 12v socket which stays live even after the ignition is switched off. You can check this by plugging in a powered device and turning the car off. Be warned though – some models have a delay, so also check if the power is still there once you’ve locked the car. 

If the power is cut off from the socket, then you can use the on-board diagnostics (OBD) data port fitted to most cars in the past 20 years. The only other alternative is to run wires from the battery to the panel – but make sure that the cables aren’t cut when you close the bonnet and that the door seals won’t leak if you’ve got wires against them.

Verdict

None of these chargers is perfect, and if you are expecting the same performance as a plug-in battery charger, you’ll be disappointed, even in the sunniest weather. The Photonic Universe panel looks like it’s been made in a shed, but it offers a decent combination of performance and price. The OptiMate is easier to use and more powerful, but you pay for it. If you have a smaller battery and just want to keep it topped up, the identical AA and Halfords pair will do a decent job at a reasonable price.

  1. Photonic Universe 10W Solar Trickle Charging Kit 
  2. OptiMate Solar 20W 
  3. AA Car Battery Solar Charger / Halfords 2.4W Solar Maintainer

Photonic Universe 10W Solar Trickle Charging Kit

  • Price: £44.99 
  • Output: 10W 
  • Connections: Clips
  • Rating: 5/5 

BEST BUY Photonic Universe’s chargers aren’t designed to be thrown on the dashboard for occasional use and can instead be permanently fixed to the outside of a vehicle or building. This 10W kit has a total of five metres of cable, meaning you could leave it on your garage roof to charge a car inside, even if you’re not connected to the mains electricity. 

If we were being unkind we’d say it looks a little like a school science project, but it’s certainly effective at keeping a battery charged, on top of which it’s half the size of other chargers despite having a greater output, and isn’t a bad price either. 

Buy now from Amazon

AA Car Battery Solar Charger

  • Price: £25.95 
  • Output: 2.4W 
  • Connections: Clips, OBD
  • Rating: 4/5

RECOMMENDED Like the very similar Halfords equivalent (see page 92) the AA-branded panel looks like pretty good value, because it’s among the cheapest on test but has a reasonable 2.4kW output. 

It also has an OBD plug attachment as standard, making it far easier to install in a car that doesn’t have a permanently-live 12v socket. 

The blue LED flashes excitedly the more sunlight it sees, which is good for reassurance that the panel is actually working and gives you an indication of the best place to catch the sun. The output isn’t huge though, even in bright and direct sunlight. 

Buy now from Amazon

OptiMate Solar 20W – Automotive Package

  • Price: £139.99 
  • Output: 20W 
  • Connections: Clips, clamps, OBD
  • Rating: 4/5

RECOMMENDED The OptiMate is a big investment and is physically large, but it claims to incorporate the same sort of clever technology that it uses in its well-known battery chargers. That means it will monitor the state of the battery and deliver the appropriate charge to top up or even rescue an apparently dead battery.

The kit includes an OBD plug which makes it far easier to connect and LED lights on the control unit indicate the state of charge and how the OptiMate is treating it. It worked well when connected directly to the battery, but the OBD link seemed to confuse it. 

Buy now from Amazon

Halfords 2.4W Solar Maintainer

  • Price: £25.00 
  • Output: 2.4W 
  • Connections: Clips, socket
  • Rating: 4/5

RECOMMENDED ThIS Halfords product looks like a twin to the AA offering, but isn’t quite identical. In fact, the differences go a little deeper than the 95p discount.

This panel does without an LED indicator and the OBD connector, which might well suit your needs better. For example, the flashing light could attract unwanted attention if your car is parked on the street and will take a tiny amount of power, which could otherwise be directed to your battery. If you have an older classic or inaccessible OBD socket you might prefer the Halfords 12v plug too. Otherwise, the performance and specifications are the same. 

Buy now from Halfords

Halfords 6W Solar Maintainer

  • Price: £39.99 
  • Output: 6.0W 
  • Connections: Clips, socket
  • Rating: 3.5/5

The top-spec Halfords charger looks remarkably similar in every way to the Ring Battery Maintainer, except for a little branding and a £20 price difference. 

The first thing that strikes you about them both is the sheer size of the panels, because they are bigger than a sheet of A3 paper. That means there are more cells to absorb the sun’s rays, but it’s twice the size of the more productive Photonic Universe unit. 

This means you won’t be able to mount it to the windscreen with sucker pads and might struggle to fit it on a smaller dashboard.

Buy now from Halfords

Powoxi Solar Car Battery Trickle Charger 3.3W

  • Price: £28.98 
  • Output: 3.3W 
  • Connections: Clips, socket
  • Rating: 3/5

Powoxi makes some of the best-selling solar chargers on Amazon, and it appears to be decent value, with a tough casing and large suction pads to attach the unit to a window. 

A blue LED illuminates to show it is receiving power from the sun and the claimed output is reasonable enough at 3.3kW. In reality, though, the output didn’t actually match that of the supposedly less-powerful AA and Halfords chargers in this test. 

While it might keep a battery topped up if there is a light load, such as a clock or alarm, it would struggle to trickle charge a dead battery.

Buy now from Amazon

Sealey 1.5W Solar Power Panel

  • Price: £23.94 
  • Output: 1.5W 
  • Connections: Clips, socket plug
  • Rating: 2.5/5

The Sealey has the lowest output of any charger here at a measly 1.5W, which means it wouldn’t be able to power a small LED bulb. 

Nevertheless, it may just be enough to keep a battery charged over a very long period if the only load is something small, such as a clock. Unfortunately, in overcast conditions the wattage produced barely registered on our meter. 

The upside is its tiny size; it’s only a little bigger than a sheet of A5 paper and has a soft frame to prevent it damaging your car’s trim. There are better chargers that cost only a little more though.

Buy now from Amazon

Ring Solar Power Battery Maintainer

  • Price: £59.90 
  • Output: 6.0W 
  • Connections: Clips, socket
  • Rating: 2.5/5

Ring’s 6.0W charger must be made in the same factory as the Halfords Solar Maintainer because we couldn’t spot a difference in the look or performance in the two products except for some branding. 

That means it’s big, frill free with no flashing LEDs and just basic clip and socket connectors. That might be all you need and it’s a decent enough product, but the Ring is £20 more expensive with no more features.

That makes it impossible to recommend, unless you find it somewhere on a special offer that brings the price down to the level of the Halfords unit.

Buy now from Amazon

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