Portable Solar Generators: Clean, Quiet Power Wherever You Go

When the power lines went down during a storm, or the campsite is well off-grid, a loud petrol generator and a jerrycan of fuel gets the lights back on. New solution: A portable solar generator stashes energy away in a battery, and can power up your phone or even a mini fridge by the side of the road using nothing more than the power of the sun.

What Is a Portable Solar Generator?

It's called a solar generator, but it doesn't work by creating power from combustion. It's actually a power station that consists of:

• A battery pack, typically lithium-ion or lithium iron phosphate (LiFePO4) that stores the energy.
• Inverter – Changes the battery's direct current (DC) to the alternating current (AC) that applies in your household appliances.
• A charge controller-a device that limits the power coming in from the panels so the battery can charge safely.
• Output ports - usually AC power outlets, USB-A, USB-C; and even a 12V Power outlet like car power interface.

How do you connect solar panels? Solar panels are typically sold as separate items. They link to the unit and provide the unit with energy from the sun, although most units are capable of charging from a socket or a 12V socket in your car.

Why People Are Choosing Them

Quiet to run. Fuel generators are noisy enough to make neighbours and wildlife resent them. Solar generators make only a whisper under heavy load.

No fumes. As they don't burn fuel, you can operate a wood-fired stove inside, unlike a petrol or diesel device that you should never use indoors because of the risk of carbon monoxide poisoning.

Very low operating cost. Sunshine is free. There are no fuel costs to buy, store, and transport once the initial purchase price is paid.

Little to no servicing. No oil changes, spark plugs or carburettor flushing. The key service requirement is making sure the battery stays charged and stored properly.

Versatile. Use it as a backup if the power goes out at home, a power pack for camping and van life, or a power station at the work site for remote jobs.

Understanding the Specs

You want a unit. You've gotta learn the numbers.

Cap (Wh). This is how much power the battery pack can store (measured in watt-hours). The bigger the number, the longer it can power a piece of gear. A 500Wh pack, for example, should power a 50W device for ten hours in an ideal world, although real usage will be slightly less (due to conversion efficiencies).

Output (W). This is the amount of power the inverter can give out at any one time. A 1000W inverter can operate a 900W appliance but not a 1500W one. Also look at the surge rating as certain products like fridges and pumps use more power at startup because they contain motors.

Solar input (W). This indicates the amount of panel power the unit can handle. The higher the input figure the quicker the battery will recharge in good sunshine.

Battery chemistry: LiFePO4 batteries typically have several thousand charge cycles and may be slightly heavier than traditional lithium-ion batteries, but are more thermally stable.

How to Size One for Your Needs

The easiest way is to add the loads you want to run together then estimate the number of hours a day they will be used and multiply.

• Smartphone charge: 10W, 2 hours = 20Wh
• Laptop: 60W, 4 hours = 240Wh
• LED lights (set): 15W, 5 hours = 75Wh
• Small fan: 40W, 6 hours = 240Wh
• Compact fridge: 60W avg., 24 hours = ~700Wh

If you need a unit to power a couple of phones, lights and a laptop during a weekend camping trip, 300 – 500Wh should be enough. For a home backup power supply to run a fridge, router and lights in an outage then 1000Wh and more may be what you're after. Whatever the total you get, add a 20 percent buffer for efficiency.

Choosing the Right Solar Panels

There are two main styles of panels. Fold-able panels are light-weight, portable, and good for travel. Rigid panels are more durable and usually more efficient which makes them preferable for permanent installations such as in a garden or on a roof.

Align your panels to the power handle range of the generator, especially the voltage and the maximum wattage. Going over the voltage range will set off a shutdown, or damage the item. As a very basic rule-of-thumb, a 100W panel in bright, direct sunlight may provide 60-80W of power available, which means it would take a complete day or more to recharge a 1000Wh battery from empty using just one panel. Two or three panels in parallel make for a much more realistic recharge time.

Placement is just as important as size Angle the panel toward the sun. And keep the panel free of shade (shade on even a single cell can dramatically reduce output), and tilt through the day if you're able.

Practical Uses

Backup at home. In unreliable power grid areas, a solar generator can provide power for – lights, fans, wifi, charging phones – and even a refrigerator if it has sufficient capacity.

Camping and outdoor fun. Keep the cameras running, power a portable cooler or illuminate the campsite without disturbing the peace and quiet.

Free flight. Freelancers, photographers and field researchers can work remotely far from the grid.

Events and markets. Vendors have the ability to make lighting and payment devices operate by using their own energy, without having to lug around a noisy generator.

Emergency preparedness. A fully charged unit will enable communications and some comfort if and when the infrastructure is gone.

Limitations to Keep in Mind

Portable solar generators are the best. But knowing when they're out of their depth will help you not cry when you can't get "one more hour" out of them.

• They aren't made for heavy demands. All air conditioning units, electric heaters and some power tools will run batteries down extremely fast. A good number of the power tools and AC units will be greater than the inverter can output.
• Time to recharge Weather affects recharge time. On dull days or in the depths of winter, you won't get as much sun and so recharging takes longer.
• Upfront cost is greater than a basic fuel generator with comparable peak output but lower running costs make it a better investment in the long term.
• Weight is variable. Some larger boxes can weight in excess of 15kg so "portable" is a subjective term.

Tips for Getting the Most from Yours

1. Keep it between roughly 20 and 80 percent for storage if you won't use it for weeks. Top up every few months.
2. Protect the battery from temperature extremes. Never leave the unit inside a closed car or in direct sunlight. Exposure to high temperatures will reduce the battery life.
3. Use DC outputs whenever possible. When charging a phone, it will always draw less power when it's charging through the USB port versus the AC inverter.
4. Use energy-efficient appliances. LED lights and laptops are much more battery-friendly than older, more power-hungry devices.
5. Test early and often. Run your critical devices on the unit at home so you'll know the actual runtimes in the event of an emergency.

What to Look for Before Buying

Safety specs/other features: Further than capacity and the output, look at the warranty length, the quantity and types of ports, pass-through charging (can you use it while it's being charged), and if it has a pure sine wave inverter (safer for more sensitive electronics). Look for safety certificates and look for independent reviews, not only manufacturer specifications.

The Bottom Line

This isn't a whole-house power station that will replace your fuel generator, but in a pinch, for life's little "let's go camping" moments, or a construction site that's not grid-connected, this is something a fuel generator can't do: clean, silent, renewably sourced power ready to go, on demand. Do a rough calculation, and choose the right panels to maximize the unit, and you'll have a reliable power source that's working for you as long as the sun rises.