LOW←TECH MAGAZINE English

Winter is Coming: Build a Solar Powered Foot Stove

Sun, 16 Nov 2025 00:00:00 +0000

Image: The electric foot stove that we build in this manual. Photo by Marie Verdeil.

We built an electric cube heater, powered by a 100-watt solar PV panel. During the day, the solar panel slowly heats the cube, which radiates heat to its surroundings. Due to its high thermal mass, the object continues to radiate heat for hours after sunset.

Electric Foot Stove

The heat cube can serve multiple purposes. You can use it as a modern variant of a preindustrial foot stove. Put your feet on the cube and throw a blanket over your lap to trap the heat.

Historically, foot stoves contained glowing sintels from the fireplace, but an electric version is safer and healthier. There is no risk for carbon monoxide poisoning or fire. The heat cube contains no flammable materials.

Image: A nineteenth century foot stove. Source: Museum Rotterdam (CC BY-SA 3.0).

You can also put the cube under a table that has a blanket on top, and that is another method to build an electrically heated table. The heat cube can also quickly dry a pair of socks or keep a prepared dish warm in the kitchen or on the table.

Rather than storing electricity from a solar panel in a battery to operate an electric heater at night, the solar panel stores heat in the thermal mass of the heat cube itself. That’s cheaper and more sustainable, because batteries account for 70-90% of the money and energy invested in an off-grid solar PV system.

Heat can be stored for even later in the night by covering the cube with one or more wool blankets.

Image: The heat cube used as a hand and foot warmer. Photo by Marie Verdeil.

Bricks, Mortar, and Tiles

We created the heat cube using inexpensive and simple materials: bricks, mortar, and tiles. The solar panel supplies power to an electric resistance heater, which we made ourselves and which we laid between several layers of bricks. The electric resistance heater connects directly to the solar panel, without a solar charge controller or voltage regulator in between. If you add more solar panels, the heat cube also works in cloudy weather.

Electric Tile Stove

Our heat cube is relatively small (20x20x25cm), but this manual can serve to build a much larger version, which could take the form of an electric tile stove, which could include a heated bench or sleeping platform.

Tile stoves date back to the Middle Ages and accumulate heat from a biomass fire within a stone or brick mass. They are fired only once or twice per day and continue to radiate heat for approximately 12 to 24 hours. However, a tile stove can also work electrically. In that case, there is no need to add a labyrinth of smoke channels that delays the release of heat through the chimney; instead, only layers of bricks with electric heating elements in between are required. Neither do you need a chimney.

Image: A 1920 tile stove in the "Tautes Heim". Source: www.tautshome.com (CC BY 3.0).

Tile stoves are very heavy, and powering them electrically doesn’t make that any better. Once built, they remain in place. Even our small cube heater is not precisely a portable device: it weighs 26 kg. If you want to move it around, it’s a good idea to put it on a wooden board with wheels mounted underneath. Make sure it can’t slide down a slope.

Solar Oven vs. Foot Stove

This solar-powered cube heater forms part of a larger collection of devices that we built, including a solar powered oven and a solar powered coffee maker. They are all based on direct solar power and heat storage rather than electric energy storage.

All these devices are inspired by tile stoves. However, while the solar oven and coffee maker are designed to keep the heat inside, the cube heater is designed to radiate heat outwards. Therefore, it is the only appliance that has no thermal insulation. That also makes it easier, quicker, and cheaper to build than the others.

Thermostat

The heat cube we built works without a thermostat. Because it has no thermal insulation, there is little danger of overheating and damage to the electric resistance circuit. It’s the room that gets warmer: the cube continues to radiate heat into its environment and maintains a steady temperature. Furthermore, the sun goes down every evening, cutting off the power supply.

However, overheating could occur when you charge the heater with one or more blankets on top, effectively adding insulation, or when you operate it on grid power using an AC/DC converter. To avoid this, you can add a thermostat, which turns off the power source when the surface temperature exceeds a preset limit.

A thermostat can also be helpful when the heat cube surface becomes too hot to touch with bare skin. However, you can also wrap a blanket around it or make a fitting cover, similar to the ones used for hot water bottles. Installing an on/off button provides you with a manually operated thermostat.

What You Need

Six bricks. We used refractory bricks (also known as fire bricks), which are used in high-temperature environments. Refractory bricks are made of silica and store thermal energy very well. However, regular bricks work as well, because they withstand temperatures much higher than those reached in the cube heater. Just make sure the bricks have a 1:2 size ratio, allowing you to create a pile with alternating brick layers.
Mortar. We used regular construction mortar, which can withstand temperatures up to 300°C. Refractory cement combined with sand and water could also work. However, it’s not a requirement because the heater doesn’t reach a temperature of 300°C.
Electric resistance heating element. We made a 100-watt electric resistance heater, which we fixed in the mortar between the bricks. It’s made from nichrome wire and heat-resistant electric cables. See our separate manual.
Tiles. We used ceramic tiles to cover the sides and the top of the cube, and a thicker floor tile at the base. The tiles radiate heat, waterproof the structure, and help to keep it together.
Adhesive mortar. To paste the tiles to the bricks.
A fuse. You add this in the positive wire between the solar panel and the heat cube. Its Amps rating should be slightly higher than that of the heating element. Read more about fuses.
A thermostat (optional). In contrast to the other devices in this collection, the heat cube does not have a thermal switch and thermal fuse. You could add a thermostat to regulate the temperature of the heat cube (see our manual on building an electrically heated table).
An on/off switch (optional). Add this when you don’t have a thermostat.

Image: Step by step instructions to build the heat cube. Illustration by Marie Verdeil.

Building steps

Cut a large and thick floor tile into a square. Its dimensions should be bigger than two bricks lying side by side. We have more information about cutting tiles in the solar oven manual.
Prepare the heat-resistant circuit of 100W. Since we have three layers of bricks, we prepare two separate strands of nichrome wire to evenly spread the heat. One strand goes between the first and second layers of bricks, and the other between the second and third layers. Solder both strands to heat-resistant electric cables. Next, connect these heat-resistant electric cables in parallel. To decide the length and the thickness of the nichrome wire, and other building steps, consult our separate manual.
Prepare some construction mortar following the package instructions. Apply some mortar to the bottom tile and place your first brick on top of it. Add some mortar on the inner side of the second brick before pressing it next to the first brick.
Add a generous amount of mortar on top of this first level and place the first part of the resistance circuit, ensuring the nichrome wires are spread evenly, don’t cross, and remain in the center. Take care that the nichrome wire doesn’t come closer than 5 cm to the sides of the cube, otherwise the surface becomes too hot.
Cover with more mortar and layer a second level of two bricks, perpendicular to the first one.
Place some mortar on top of the second level before laying down the second part of the circuit. Make sure the ends of both circuits are on the same side of the cube and that the heat-resistant cable ends extend at least 5 cm beyond the cube. We will connect them in parallel later.
Place the last layer of bricks, perpendicular to the second level. Use the leftover mortar to fill the holes on the edges of the bricks.
Wait 24 hours for the mortar to cure.
Solder the two separate circuits together in parallel, ensuring there are a few centimeters of space left to extend the circuit with regular cables later.
Prepare some adhesive mortar and cut the tiles for the five sides of the heating cube (except the bottom).
Drill two holes for the cables through the tile on the side where they stick out.
Apply generous amounts of adhesive mortar on all sides and cover the surface. Let it dry according to the mixing instructions.
Once dry, apply grout in between the tiles’ edges.
Connect regular electric cables to each strand to create a power supply cable. We made it 1m long. Optionally add connectors at the end of each cable. The simple resistance circuit has no polarity.

Image: Six bricks form the main mass of the heat cube. Photo by Marie Verdeil.

Image: All bricks are fixed to each other with a mortar layer that also has the electric resistance heating elements inside. Photo by Marie Verdeil.

Image on the left: Tiling the heat cube. All tiles are provisionally taped around the bricks. Image on the right: Grouting the cube. Two holes in the side made to let the cables pass through. Photos by Marie Verdeil.

Credits:

Concept: Kris De Decker
Design: Marie Verdeil
Construction and documentation: Marie Verdeil, with assistance from Hugo Lopez.

Thematic Book Series: Too Much Combustion, Too Little Fire

Tue, 04 Nov 2025 00:00:00 +0000

Image: Book cover.

Buy the print edition.
Buy the epub edition.

For most of history, the multifunctional fire was the only source of energy in the household. It served as a cookstove, toaster, heating device, lighting source, hot water boiler, clothes dryer, and refrigerator, among other functions. During the twentieth century, the fire was replaced by a wide range of appliances plugged into central infrastructures.

In this series of articles, LOW←TECH MAGAZINE critically examines the efficiency, sustainability, health, and safety of the fire and its flame- and smoke-free modern alternatives. What are we saying when we argue that electrical appliances are “better” than a traditional fire?

Contents table

Too Much Combustion, Too Little Fire
Thermo-electric Stoves: Ditch the Solar Panels?
How to Make Biomass Energy Sustainable Again
Well-Tended Fires Outperform Modern Cooking Stoves
If We Insulate Our Houses, Why Not Our Cooking Pots?
Wood Gas Vehicles: Firewood in the Fuel Tank
Medieval Smokestacks: Fossil Fuels in Pre-industrial Times

Available in our bookshop

Patrons get free access to ebooks, as well as early access to new print books at a reduced price.

Other books in the series

How to build a low-tech internet?, Kris De Decker, Roel Roscam Abbing, Marie Otsuka, 2023. Ebook edition.
How to downsize a transport network?, Kris De Decker, 2023. Ebook edition.
Heating people not spaces, Kris De Decker, 2024. Ebook edition
How circular is the circular economy?, Kris De Decker, 2025. Ebook edition

The Low-tech Magazine archives are also available as a chronological series consisting of four volumes.

How to Mount a Balcony Awning

Wed, 09 Jul 2025 00:00:00 +0000

Hi Kris,

I’ve been reading your website for quite a while. It’s one of my favourite blogs. Thank you for what you are doing!

We are currently experiencing a heat wave in Germany, so I drew inspiration from Low-tech Magazine’s article “How to Dress and Undress your Home” and built an awning on my balcony. I documented the process so that other readers can install one themselves.

The overall cost for my build was around 50 Euros, but you can do it much cheaper by using upcycled materials. It requires only a few tools to build, so almost anyone can reproduce it.

Required materials

Steel cable (or rope). I went with a 4 mm galvanized steel cable. I want the build to be sturdy and be able to withstand strong winds. A 3 mm cable would probably work as well. Warning: Some inexpensive steel cables have a plastic outer shell, which may reduce their strength due to the smaller diameter of the steel cable. For example, a 3mm cable would have a 2mm or 1.5mm steel core. You could also use rope instead of steel cable, which will be cheaper.
1 x turnbuckle
2 x cable thimbles
8 x cable clamps. There are different styles of clamps. The one I’ve chosen is also used in heavy construction.
1m petrol hose with 6mm inner diameter.
1m x 3m awning fabric. The distance between eyelets should be 50 cm.
7 carabiners. This number depends on the number of eyelets you have and the number of attachment points you will use.
Some paracord. It comes with the awning fabric, and I have no idea how long it was.

Image: Required materials. Photo: Dmitriy Kurochkin.

Required tools

Wrench or spanner for cable clamps
Something to cut the steel cable. Here are some options:

Metal chisel and hammer
Cable cutter
Hacksaw
Angle grinder
Hardware shops will cut the cable to the desired length

Source links

Building steps

Measuring

Image: The south-facing balcony. Photo: Dmitriy Kurochkin.

The required cable length is the distance between the posts plus one or one and a half meters. It’s better to have a little more cable than you need. It’s easy to cut extra wires, but it isn’t very easy to join cables if you don’t have enough. In my case, the distance is 3.8 m, and I used just under 5 m of cable.

Prepare the cable

The upper support for the awning consists of two pieces. The shorter piece is attached to the left post and has an eyelet. The longer piece is fixed to the right post and has a turnbuckle attached to the other end.

Tip: Wrap the area where you plan to cut the cable with electrical tape to prevent fraying. See this video.

The images below illustrate an example of how to use a thimble and cable clamps to secure the turnbuckle. You are probably fine using just one clamp, but for safety, I opted for two clamps. You should tighten the clamps very well until you see some deformation on the cable. Always place the loaded end of the wire on the base of the clamp and the free end on top of it.

The image at the bottom shows how the shorter piece of cable should look before the installation. The hose has two functions. It prevents damage to the posts and provides a perfect grip to avoid slipping. The image in the top right corner shows how the turnbuckle is attached to the longer piece of cable.

Image: Preparing the cable. Photo: Dmitriy Kurochkin.

At this point, I finished all the preparations I could do inside the house.

Assembling

Now it’s time to move outside and start final assembling. When tightening the cable around the post, leave some slack. You should be able to adjust the cable up and down to suit your needs later.

You need to unscrew the turnbuckle fully. There should be no tension on the cable between the posts. You should be able to get the hook on and off easily. Now, you are ready to position it as desired. Use the turnbuckle to put tension on the cable.

Image: Tightening the cable around the post. Photo: Dmitriy Kurochkin.

Fasten the fabric

Use carabiners on every top eyelet. You can use carabiners or rope to secure the bottom of the fabric to the railings.

Image: Fastening the fabric. Photo: Dmitriy Kurochkin.

Final result

I’m happy with the outcome. I can finally spend time on my balcony, even on sunny days. There was way too much sun in the summer as my balcony faced south.

Image: The mounted awning. Photo: Dmitriy Kurochkin.

Image: The folded awning. Photo: Dmitriy Kurochkin.

Image: The mounted awning. Photo: Dmitriy Kurochkin.

Retrospective

What went well?

Excellent protection from the sun, and I saved quite some money
The choice of materials was quite good in terms of quality
It’s easy to operate. It takes less than 30 seconds to fold and unfold it.
The build is very sturdy and can withstand wind. It handles medium-strength wind without any issues. I’m waiting for a strong wind to test.

What can be improved?

I purchased an awning fabric that was slightly too small. It would be better to have a 1.5m x 3m area. I had to experiment to find the best position for the awning.
I have some leftover hardware, including hose clamps and turnbuckles. I could save some money by buying everything separately in the local shop.
I’m still thinking about how to fasten the bottom of the fabric in a better way. An elastic cord might be a good option.

Wall and ceiling mounts

If you don’t have a post to attach the cable, your only option is to attach the cable to the wall or ceiling. Wall and ceiling mounts come in many different forms and shapes. It should be able to handle at least 100 kg, as wind gusts might be pretty intense. Generally, the stronger it is, the better. It uses screws and dowels to attach to the wall. It will require tools for drilling, such as a hammer drill and a drill bit suitable for the type of wall material being used.

You can use the keywords “ceiling hook,” “hanging chair mount,” or “eyelet plate” to find it online.

Below is an example of a complete set from the Toldoro manufacturer.

Image: Ceiling hooks.

Safety precautions

Learn how to safely use all tools before starting. Read manuals or watch quick guides if needed.

Wear gloves when handling steel cables. Frayed ends can cause cuts or puncture wounds on your skin.

Use a stable stepladder for installing upper lines. Place it on flat ground and don’t overreach. Consider having someone nearby to assist.