How to Assemble an Electric Heating Element from Scratch

Summary

Image: A removable heat brick, consisting of a nichrome circuit sandwiched between two identical tiles. It rests upon an insulated solar electric cooking device. Photo by Marie Verdeil. View original image View dithered image This manual documents the building of an electric resistance heating element that is directly connected to a solar panel, without a battery, charge controller, or voltage regulator in between. The heating element is used in the insulated solar electric cooker that we describe in another manual, and in the solar-powered coffee maker and footstove that we will document in forthcoming manuals. We also describe a method to make a removable heat brick, which we use to replace the commercial heating elements in some earlier electric solar cooker prototypes we made. A custom-made electric resistance consists of an electric circuit made of nichrome wire, enclosed in a mortar layer. The length and thickness of the nichrome wire determine its current draw at a certain voltage, meaning that you dimension the circuit to your solar panel voltage and power rating to optimize heat generation. The nichrome circuit is connected to the electric cables of the solar panel, with a short section of heat-resistant electric cable in between. Why build an electric resistance heating from scratch? We initially used commercial heating elements in our first solar oven prototypes, which yielded disappointing results. Therefore, we decided to build our own, based on the manual provided by the Living Energy Farm. Building your own heating element involves extra work, but it’s worth the effort. It’s also a lot cheaper. Many commercial heating elements have built-in thermostats, which can complicate temperature regulation inside the oven. They also require a voltage input that does not align with the voltage output of most solar panels, which introduces the need for an extra electronic component (a buck converter). Securely fixing commercial heating elements proved to be diffi...