Can a solar panel power a kettle?
If you had multiple solar panels connected to a correctly sized inverter, then yes, you could power a kettle from your solar panels when the sun is shining.
Electric kettles draw a lot of power even though they don’t run for very long. You’ll need to connect several panels to produce enough watts to power your kettle.
The solar panels will also need to run through an inverter that’s large enough to handle the load.
To boil a kettle when it’s dark or cloudy (i.e. your panels aren’t producing any power) you’ll have to draw power from a charged battery bank.
I’ll go over the details for you in this post and I’ll also show you some alternative ways you can boil a kettle off grid.
How Many Watts Is Your Kettle?
Before you can work out how many solar panels you need to boil a kettle, you need to know how much power your kettle will draw.
If you look on the underside of your kettle, you should see a label detailing how many watts the kettle uses.
A fairly typical rating is 1500 watts. But you can find kettles with lower power consumption of 1000 watts or so.
If you’re shopping for a kettle, look on the box in the store, or if you’re online, look at the product listing for the power rating.
How Many Solar Panels Will You Need To Boil A Kettle?
This isn’t as straightforward to work out as you might think because solar panels don’t produce a constant rate of power.
Their output varies based on their individual sizes and the amount of sun hitting them, which varies according to the weather, time of day, and the latitude of your location.
If you’re pulling a face right now because you want a simple answer to what appears to be a simple question, I know how you feel. I’ve felt the same way many times over the 12 years I’ve used solar power at my home.
But the fact is, this isn’t a simple question! With off-grid solar there aren’t many simple questions.
So let’s dive a little deeper.
You know how much power the kettle will draw, and this tells you how many watts you need your solar panels to produce.
For a 1000 watt kettle, you need solar panels that will supply 1000 watts.
For a 1500 watt kettle, you need solar panels that will supply 1500 watts.
For a 3000 watt kettle, you need solar panels that will supply 3000 watts.
Here’s where it gets tricky.
To generate 1000 watts, you might think you could simply connect four panels rated at 250 watts because 250 x 4 = 1000.
But you would be wrong.
And that’s because panels only give their rated power under very narrow conditions.
As already mentioned, to get the maximum power from your panels, they must be in full sun and set at the correct angle based on latitude and season.
Use a Solar Angle Calculator like this one to work out the optimal angle for your panels, so they will give you their maximum output.
The image below shows an example of the optimum tilt for Orlando, Florida.
Because your solar panels are unlikely to be in full midday sun every time you want to boil your kettle, you would need to do one of two things.
- Oversize your panel system so it can produce 1000 watts for your kettle even in heavy cloud.
- Add batteries so you have a store of power to draw from to make up the difference between the power you need and the power your panels are producing at that moment.
To give you an idea of panel output on a heavily cloudy day in winter, I have 2000 watts of solar installed at my home, and on a cloudy day, they often only produce 300 watts.
So even though I have 2000 watts of solar panels and our example kettle only needs 1000 watts, my panels wouldn’t even turn the kettle on, let alone heat the water.
To boil a 1000 watt kettle in those conditions would take over 6000 watts of solar panel capacity.
As you can imagine, I have a battery bank with my system.
With a charged battery standing by ready to power your kettle, you’ll get hot water when you want it without needing to purchase a huge solar panel system.
To boil half a liter of water in a 1000 watt kettle takes about 3 minutes and this consumes around 50 watt hours of power. Watt hours are not the same as watts, so don’t get confused.
Watts and Watt Hours What’s the Difference?
Watts is a measurement of how much power a device uses at a moment in time. Watt hours is the total power used over time.
In our example above, the kettle draws power at a continuous rate of 1000 watts. It’s going to draw 1000 watts the whole time it’s working to boil the water.
If you ran the kettle for 1 hour, you would multiply 1000 watts by 1 hour, which would give you 1000 watt hours or 1 kilowatt hour (1000 watts is 1 kilowatt).
Because the kettle only runs for 3 minutes, divide 1000 watts by 20 (60 minutes in an hour divided by 3 minutes of running the kettle = 20) which gives 50 watt hours.
Now, perhaps you plan to boil your kettle 6 times a day. The total run time of your kettle would be (6 x 3 minutes) 18 minutes and that would use a total of 300 watt hours.
Knowing that the kettle will consume 300 watt hours, you can figure out what battery capacity in watt hours you will need. And you also know how much power you need to put into that battery from your solar panels.
Again, going by my own experience, 2000 watts of solar panels on a cloudy day, generating 300 watts, would mean that in 1 hour the battery charge will increase by 300 watt hours, which is enough to boil the kettle 6 times.
On a bright sunny day at noon, 2000 watts of solar panels would boil a 1000 watt kettle without needing any battery backup power.
If you only want to boil water at midday in full sun, you should connect enough panels together to slightly exceed the wattage of your kettle; but that’s an unlikely scenario though, isn’t it?
Most people want to boil a kettle for coffee first thing in the morning. Even in high summer, solar panels won’t generate much power at all at 6 am.
So realistically, you will need to add a battery to your system.
For boiling a 1000 watt kettle directly from solar panels, I would opt for 1400 watts of solar power running through a 2000 watt inverter.
What Size battery Do You Need To Boil A kettle?
Assuming you only want to boil a kettle 6 times a day, then you need a battery that can store and deliver 300 watt hours of power.
That doesn’t mean you can go out and buy a 300 watt hour battery though.
Why not?
Because a battery’s capacity isn’t the same as the amount of power you can draw from the battery.
Drawing too much power from a battery will damage it and render it useless in no time at all.
Different types of battery have different safe discharge depths.
Whichever battery you buy, you’ll find the discharge depth listed on the battery label as DOD (depth of discharge).
For Lead-Acid batteries (the cheapest kind of battery), the recommended DOD is 50%.
For AGM (Absorbent Glass Matt) batteries, the recommended DOD is 80%.
For Gel batteries, the recommended DOD is 75%.
For Lithium-Ion batteries, the recommended DOD is between 80-100%.
With a lead acid battery (50% DOD) to have 300 watt hours available to power your kettle safely, you would need a 600 watt hour battery, or multiple smaller batteries linked together.
But if you choose a Lithium-Ion battery with a 100% DOD, you would in theory only need a 300 watt capacity battery. To be on the safe side, give yourself some wiggle room with a 360 watt battery.
Before we look at various configurations for solar panels that can charge your battery, we need to look at inverters.
What Size Inverter Will Power A 1000 Watt Kettle?
An inverter is an essential piece of equipment for converting direct current (DC) from solar panels or batteries into alternating current (AC) which is the current that most appliances and devices run on; standard household current.
To power a 1000 watt kettle, you’ll need an inverter that is larger than 1000 watts.
Why?
The rated power of an inverter is higher than the amount of current it can deliver. This is because the inverter itself requires some power to run, and because inverters aren’t 100% efficient at converting DC to AC.
The cheaper Modified Sine Wave inverters are less than 90% efficient. While Pure Sine Wave inverters boast efficiencies of 90-95%.
With a 95% efficient 1000 watt Sine Wave inverter, you would get a maximum of 950 watts of power minus the inverter’s power consumption.
So that’s the first thing to be aware of.
The next thing to know is that if you run your inverter under a heavy load, that’s close to its capacity, it will be under strain and will run hot.
Inverters generate a little heat as they run under normal loads, and a lot of heat under heavy loads. Too much heat will shorten an inverter’s lifespan.
Better quality inverters have built in fans which help to vent the heat, but the fan will draw some power which leaves less for your kettle.
To operate your inverter without putting it under strain, you should keep your load at around 80% of the inverters rated capacity.
For a 1000 watt inverter, that would mean drawing no more than 800 watts continuous power.
Inverters can run at a higher rate for a short burst (less than 1 second) so they can handle the start up surge of motors.
This is known as surge power or peak power and will be listed on the inverter’s label. A 1000 watt inverter may have a surge capacity of 1500 watts.
That 1500 watts is only for the surge though, which lasts a split second. Don’t look at that power rating and think it will cover your kettle. It won’t.
To power a 1000 watt kettle, you’ll need an inverter with at least a 1200 watt capacity.
Now that we’ve figured out a practical size for a battery and an inverter, we can move on to solar panels for your kettle.
Choosing The Right Size Solar Panels for Your Kettle
You have several options when it comes to choosing the size of your solar panels.
Common solar panel sizes are 100 watts, 120 watts, 150 watts, 175 watts, 200 watts, 220 watts, 250 watts, 300 watts and 400 watts.
Let’s see some rough-and-ready examples.
100 Watt Solar Panel
A 100 watt solar panel operating at its peak would take around 3 hours to give you the 300 watt hours running time for your kettle. Once your battery is fully charged, you can use the extra power generated by the panel to power other devices.
On a very cloudy day when you might only get 5 – 10% of the panel’s peak output (5 – 10 watts), you wouldn’t generate anywhere close to the amount of power you would need.
If the panel generated a steady 10 watts over 6 hours of daylight, it would only produce 60 watt hours. You could boil your kettle once with that much power.
200 Watt Solar Panel
A 200 watt panel operating at its peak would take around 1.5 hours to give you the 300 watt hours running time for your kettle. All the power generated over the rest of the day is yours to use as you please.
On a very cloudy day, you may only get 5 – 10% of the panel’s peak output. Steady power generation of 20 watts over 6 hours of daylight would produce 120 watts. You could boil your kettle twice.
300 Watt Solar Panel
A 300 watt panel operating at its peak would take around 1 hour to give you the 300 watt hours running time for your kettle. You’ll have lots of spare power to use for other things for the rest of the day.
On a very cloudy day when you may only get 5 – 10% of the panel’s peak output, your panel producing a steady 30 watts over 6 hours of daylight would only produce 180 watts. You could boil your kettle three times.
We don’t need to carry on with more examples. As you can see, on a cloudy day, 100 watts of solar power, charging your battery all day will give you enough power to boil your kettle once.
To charge your battery enough to boil your kettle six times on a cloudy day, you would need 600 watts of solar panels.
And there’s still one more component you will need.
Choosing A Charge Controller For Your Solar Panels
When you add batteries to a solar power system, you’ll need a charge controller to regulate the battery charging.
A charge controller senses the voltage and state of charge of your batteries and adjusts the amount of power going in so they charge in the most efficient way. It also stops your batteries from overcharging.
A 40 amp charge controller is suitable for 400 watts of solar panels.
Make sure you match up the voltage of your panels, inverter, charge controller and batteries.
Twelve volt systems are very common and you can easily buy kits which supply all the components you need for a complete system.
These kits contain solar panels, an inverter, a charge controller, a battery, plus all the connectors you need to fit everything together.
A kit is the simplest way to get started with solar power, and you have the reassurance that all the components will work together without any mismatches or incorrect sizing issues.
Alternative Ways To Boil A Kettle Off Grid
If you’re planning a system for an off grid cabin or house, you’ll most likely want to power all kinds of equipment with your solar panels, so it makes sense to add a little extra capacity to cover boiling a kettle on cloudy days.
But what if you’re on a tight budget, or you want a fairly modest system for your RV, van conversion, camper, or tiny home?
In these cases, it doesn’t seem practical or economical to oversize your system just so you can boil a kettle when the sun isn’t shining.
A small gas camping stove is a good alternative. These stoves are cheap and the fuel canisters are widely available.
Another option is a small rocket stove.
Rocket stoves are amazing. They only need a few small sticks to reach high temperatures, which are perfect for all kinds of cooking, and they boil a kettle with ease in a few minutes.
You can choose from several models online, or if you’re handy, you can make your own. Just search on YouTube for endless demonstrations and step-by-step, how to build guides.
I made my own rocket stove out of an old spin dryer and some chimney pipe, and with just a few sticks, it boils 5 liters of water in about 5 minutes.
Final Thoughts
If you’re installing a solar power system for your house or cabin, it won’t cost you too much more to upgrade it if that’s what it takes to run a kettle; but if you just want to boil water on camping trips or when you’re out RVing, a camping stove or a rocket stove would be my choice.
