SOLAR GENERATORS: Three Questions to Ask Before You Buy

Updated on June 17th, 2022

By: Steve Maxwell

Are you looking for emergency backup power during a blackout? Solar generators convert the energy of the sun into electrical power for running and charging small items, and they’re a hot item these days. That said, there are a lot of disappointed solar generator owners out there because advertising claims often over-state the usefulness of these units. This article will help you think clearly and accurately about the situation.

Do Solar Generators Really Work?

Solar generators are portable power sources that need no fuel, they make no noise and create no exhaust. Every model on the market has four main parts. The battery stores power so it’s available for use even when it’s not sunny outside. The photovoltaic panel converts sunlight into electricity that’s used to recharge the battery. The charge controller ensures that only the right amount of electricity gets fed back into the battery in the right way, and the inverter converts the direct current (DC) power of a battery into alternating current (AC) electricity suitable for plug-in household items. I’m a big fan of building your own solar generator from parts (more on this later), but if you’d rather buy one ready-to-go, you’ll need to start by asking yourself some questions.

This is a solar generator I built from parts. It delivers the best run time and power output that’s possible, plus it’s repairable and expandable.

Solar Generator Question#1: What can you run on a solar generator?

This is the most important question to answer before you make a purchase. This is actually just the first of two different “how big” questions. The first has to do with maximum wattage of power needed. Ready-made solar generators are typically capable of putting out a maximum of 400 to 1250 watts depending on the model. How far will that kind of power output go? A cell phone, for instance, requires less than 10 watts to charge. Hardly any at all. An ordinary electrical kettle, by contrast, uses more than 1200 watts. Most electrical devices have wattage figures printed on them somewhere. Add up the numbers before you start shopping for a solar generator. If there’s no wattage figure on the device or appliance you’re looking at, look for voltage and amperage figures on the manufacturer’s nameplate. Volts x amps = watts. Solar generators don’t generate nearly as much power as a medium or large-size gasoline-powered generator, so you’ll probably need to economize when deciding what you’ll run.

Solar Generator Question#2: How long will a solar generator run?

This is the second “how big” question. Solar generators harvest light energy from the sun, converting it to electrical energy and storing this power in an on-board battery. The length of time this battery can deliver power is called “run time”. Some solar generators have small on-board batteries and others have larger ones. So, what are your needs? Identify the amount of wattage you expect to consume over a given time when the sun isn’t shining, then see how long the various models can provide this amount of power. If all you want to do is keep your laptop and phone charged while having enough power for small lights, a small solar generator will probably check out fine. However, if you’d like more capacity at night and during cloudy weather, add up your wattage numbers and figure out what run time you can expect from various models.

Solar Generator Question#3: How fast does a solar generator recharge?

The internal battery of every solar generator holds power in reserve, but it’s the size and efficiency of the photovoltaic panel that determines how quickly that battery recharges as the generator sits in sunlight. As you shop for a solar generator, be sure to find out how long it takes to fully recharge the battery. The difference between a slow-charging unit and a faster one can be quite extreme.