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Want free energy outdoors? Stick these portable power solutions where the sun does shine
With energy prices soaring, more of us are looking for all the free electricity we can get. While even the best portable solar panels and chargers aren’t powerful enough for heavy-duty jobs such as heating a water tank or running large appliances, they can easily keep phones, tablets and laptops charged up, using nothing but sunshine.
Though battery technology keeps improving, our gadgets are becoming more power-hungry, meaning the battery life of the average phone lasts just a single day. That means it’s more essential than ever to carry a back-up solar charger or solar panel when camping, going off-grid, or travelling in the great outdoors with your favourite tech.
Advances in technology mean today’s solar panels are smaller, lighter and more efficient than ever. Chargers that were once too big to carry can now be folded down to fit inside a travel case or hang from the back of your pack while hiking. So long as you’ve got enough sunlight, the best solar chargers can indefinitely extend the life of your phone, your headphones, and even your laptop.
Some solar chargers can be plugged directly into a phone to charge it, but because most panels don’t actually store any energy it’s best to connect solar chargers to a separate battery pack and charge your devices from that. Many solar chargers come with battery packs for just this reason.
Solar chargers are most often seen when camping in remote spots, attending festivals and touring through the wilderness, but they’re also used to keep the batteries of cars, motorhomes and boats from going flat when they’re not being used. Anyone with a campsite outhouse or an off-grid shed not connected to mains power can use relatively cheap solar panels to keep a portable power station ticking over too, meaning there should always be free juice in the tank when you need it.
We tested these solar panels and chargers during the summer months in the UK. Performance is reduced to about 20 per cent during the winter months, as, even on a perfectly clear day, the sun is lower in the sky and therefore weaker. Thanks a lot, science.
We tested a range of solar chargers for different use cases, from large, fold-out models capable of powering multiple devices at once, to portable power banks with convenient built-in solar panels. We trialled them under the changeable weather conditions of south England, as well as while camping and at a festival in Portugal (admittedly our tester had access to wall power, but for the purposes of review they went as long as they could without). These are the ones that really shone.
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The Goal Zero nomad 20 is a flat and highly portable solar charger designed for backpackers and campers who want to travel light but need something more than a basic 5W panel. Half-a-metre wide when unfolded and weighing less than a laptop, it has an adjustable kickstand for aiming it directly towards the sun when placed on the ground. The rugged plastic frame has an attachment point on each corner, so you can strap it to a backpack or secure it firmly in place wherever it needs to be.
We liked that the USB output is on a lightly flexible arm, which helps prevent wear and tear on your charging cables. You can also chain multiple panels together with the included 6ft-long chaining cable to speed up charging.
This ultra-thin 5W solar panel is an all-in-one solution and, unlike other solar chargers in our list, has an integrated 2,200mAh battery pack embedded on the back. That’s about enough to charge your phone once, which is all you need in an emergency.
It has a simple wire-loop kickstand that can be threaded through a backpack strap, hooked from a tree branch or used to prop the panel up on the ground. Eyelets on the bottom corners also prevent it from sliding out of the sunlight as you walk. We liked the incredibly simple sundial on the corner of the device, which allows you to accurately aim the panel directly into the sunlight for maximum efficiency.
The Ecoflow 220W is a dedicated solar panel that produces roughly ten times the wattage of the next best entry in our list. This does make it less portable, but also way more useful for charging the specialist batteries needed to power small appliances at campsites, off-grid rental lodges, caravans, and for emergency home backup should your electricity ever fail.
The solar panel is bifacial, meaning it’s got a second 155W panel on the reverse side. This allows it to pick up a small amount of bonus current by absorbing some ambient light in bright conditions, which creates a more even power distribution in changeable weather conditions and so less wear on the device it’s charging.
We tested the 220W panel with Ecoflow EF3 Delta power station, a 14kg beast of a battery that features four USB-A ports (two fast-charging), two USB-C ports and four three-pin plug sockets. The station can be slow-charged by solar panel, or by mains power in less than two hours.
The hefty 28W output of this BigBlue solar charger enables it to deliver a consistent charge even in cloudy conditions, making it ideally suited for replenishing battery packs, smartphones and tablets while camping and hiking. The four-panel charger includes a digital ammeter for monitoring amperage and the ability to detect the voltage and resistance of the battery it’s connected to, preventing overcharging or damage to electronics.
It folds down to less than the size of a sheet of paper, but can be easily attached to the top loop of a backpack when unfurled to charge up to two devices while you walk.
Decathlon’s Trek 500 is a 10W solar charger with a single USB port, ideal for keeping battery packs topped up while on the move or camping. A respectable power output places this versatile panel somewhere in the middle of the range, delivering more energy than a small trickle charger but less than a larger and more expensive solar panel.
The dual-panel design packs away neatly into a fabric pouch and can be firmly strapped to a backpack with the help of included carabiners and eight anchor points. A reliable charging solution that straddles the gap between low-and-slow panels and more serious hardware, the trek 500 suits casual campers and long-distance walkers.
A folding solar charger with 28W output in optimal skies, this four-panel BigBlue solar panel can recharge three low-draw, 5V devices at the same time through its three USB-A ports. Powerful enough to slow-charge tablets and other high-drain mobile devices, this solar charger has a flexible design that’s useful for hanging from your back as you walk, from your tent as you camp, or from a window frame for household power. It comes with carabiners for attaching it to a rucksack or frame.
This is a 25,000mAh battery pack with a fold out four-panel solar cell, which produces enough photonic juice to trickle-charge the pack’s power reserves over time. These super-portable chargers are limited by physics, that old killjoy, so don’t expect the rinky-dink panels to kick out enough energy to be able to run a laptop or survive entirely off-grid. They’ll charge the battery pack to full given a few days of bright, sunny weather.
Still, if you’re after a rugged outdoor power bank with a built-in LED torch that can top itself up in the background while you’re setting up camp and wrestling bears, this is a convenient and useful little gadget to have in your pack.
If your car battery has a tendency to run dry when left idle for too long, you need a solar-powered car-battery maintainer. Even in the photon-averse British weather, a solar panel affixed to the inside of your windscreen can trickle enough charge into the battery to keep it refreshed and ready to go.
This 10W solar charger can be placed inside your car, but it’s waterproof and durable enough to be positioned outside for better efficiency. It clamps directly to the battery using crocodile clips or can deliver charge via your cigarette lighter if the car’s electrics allow it. The power output is rated for charging larger batteries, such as those found on boats, barges and trucks.
Before buying a solar charger, it’s important to factor in what kind of trips you will be using it for. Typically, there are three things worth considering – output capacity, surface area and the flexibility of the panels.
While performance varies from model to model, most models can last upward of three years, with some of the more premium designs claiming to last an impressive 25 years.
Yes, but the amount of energy harvested by the panel will be greatly reduced, especially if the glass is tinted or has UV light-blocking properties. According to Sol Volatics, a website that provides advice on solar panel installations, the efficiency of a panel can be reduced by up to 50 per cent, depending on the thickness and cleanliness of the glass. So yes, a solar panel left in a car on a sunny day will continue to work, but it’ll charge up a battery far less quickly than when outside in direct sunlight.
Portable solar chargers are best used to power small electrical items, such as smartphones and portable battery packs. They can be perfect for topping up the batteries of devices you might take on a camping trip, but generally aren’t much help when it comes to feeding more power-hungry products, such as televisions, portable fridges and kettles.
Some portable solar panels, such as the Ecoflow 220W (£399, Hampshiregenerators.co.uk) highlighted earlier, cost much more than others, are significantly larger, and therefore will harvest more energy. Such panels can, eventually, fill up an equally large portable battery pack capable of running anything with a domestic three-pin plug, but how quickly the battery charges will depend on weather conditions and how much sunlight the solar panel is exposed to.
Also, don’t forget that a solar charger with a higher output, measured in watts, will charge up a battery more quickly. So the 220W panel from Ecoflow will charge a phone more quickly, in the same sunlight, than one rated at a lower wattage.
As ever, it’s complicated. The energy harvested by the solar charger costs absolutely nothing, so yes, if a smartphone or portable power bank is charged exclusively from a solar panel, that energy will have been free. However, you have to factor in the initial purchase cost of the charger, before working out whether using the panel will save you money.
The long-term answer is yes, but only once you have harvested enough energy to have saved more money than the panel cost in the first place. A top tip is to carry an empty portable battery each time you use your solar panel. That way, even once all your devices are charged up – while out hiking on a camping trip, for example – you can top up the spare, empty battery whenever the sun is shining, so that free energy will be ready to use later.
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Obviously, solar panels don’t work without sunlight to power them. If you live somewhere with reduced or zero sunlight during the winter months (which includes the UK and parts of North America), you’ll see a dramatic downturn in solar panel energy output when the sun is low in the sky.
To supply electricity in a remote area with little sunlight, you’ll either need a very large battery pack to store up what little solar energy is available, or a fully fuelled diesel generator. The latter is by far the cheapest way of powering remote sites or an entire home, and, to deal with emergencies, they can be set up to kick into action in the event of power loss.
The Goal Zero nomad 2 has everything you might need in a solar charger: high wattage, an abundance of USB ports and a business-like folding design and the leading monocrystalline panel type.
For mains-style power output on demand, the Ecoflow portable power station and 220W panel is highly recommended.
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