For years I have been using excess solar power to heat my home with various types of directly PV powered DC heaters. I wanted to help beginners who want to try tapping direct PV Solar power to heat their home or shop.
So I created a detailed video guide (it’s posted below).
Background
Previously, I showed a variety of modified AC space heaters that can take a direct DC PV feed. But those can be finicky to modify and require fairly advanced knowledge. There are also safety concerns, even if the modification work is properly done.
In this guide I propose using using common DC car / truck cab heaters in a PV-to-Load (PV2L) model – that is to say, running directly off of the solar panels with nothing in between. I did this years ago, heating my bedroom during winter as an experiment. It worked and was very successful.
Case for direct Solar PV heating
It makes no sense to burn charge controllers, batteries and inverters to generate heat in the day time. These components are costly and have a limited MTBF (mean time between or before failure). Complex systems such as heat pumps may deliver twice or more heat per Watt, but at 50-80X the [installation and maintenance] cost of plugging in a simple DC heater. Solar PV can provide heat directly at minimum cost, a minimum level of technology and with few moving parts.
Solar PV electric heating is a great way to reduce dependence on gas, wood burning, grid power and other more complex and expensive heating sources.
Many solar power enthusiasts already have existing solar panel arrays installed, and once the batteries are full, the solar panels just sit in the sun getting older. Why not use all that excess solar power for directly heating the living and working space?
It is true that Solar PV captures much less heat than other methods. Solar thermal easily captures more heat – but with significant downsides. Solar PV heating using existing solar infrastructure which is not fully utilized makes perfect sense. In fact, it helps pay for the solar panels faster by ensuring closer to 100% utilization during the winter.
Heater types
To get up and running with low cost and minimum effort, it is possible to connect common off the shelf car and truck cab heaters directly to PV solar panel arrays. They are simple DC powered devices designed to heat a car or truck cab or defrost the windshield.
There are 2 main types of these heaters: resistance wire and Positive Temperature Coefficient (PTC).
The resistance heaters use a standard wire wound heating element. Basically they contain some resistance wire that heats up when a DC current is passed through it. This is a very simple and cheap way to manufacture a heater and extremely common. But they are vulnerable to overheating and usually need a fan to keep them cool.
PTC heaters pass DC current through a ceramic material which greatly increases its resistance with temperature – hence the term Positive Temperature Coefficient. The hotter it gets, the greater its resistance. This means if it overheats, the resistance gets too high and cuts heat output. The end result is extra safety. If the fan fails, usually a PTC element will throttle itself down and reduce power output.
Safety Considerations
Both of these heater types are affordable, off the shelf DC “space” heaters which were not intended for home use, but rather car or truck environments. They should never be left running unattended. I recommend installing them on cement board or fireproof surface.
The heaters can be switched on and off using a common PV circuit breaker which can handle DC arcs (a concern when the DC voltage exceeds 20V). All wiring and controls should be similar in quality, competence and standards to any other installed PV Solar power system. It’s the same technology and infrastructure, but used in a slightly different way.
Learn More
For a more resources and a detailed and thorough examination of PV DC heaters, check out my videos below. Thanks for reading! DD
Want to help support my work? Here are optional Amazon affiliate links to products shown in the presentations and blog posts. I earn a tiny commission if you purchase anything through these links. Thank you 🙂
PARTS LIST
Recommended PV DC Circuit Breaker MCB
Example (PTC) 12V 100W Heater for Experimental heating | 24V PTC |
12V 600/800W (non PTC) Car/Truck cab heater | 12V 600W (non PTC) Car/Truck cab heater
12V 400/600W Car Truck Cab Heater (non PTC) | 12V 800W dual Car Truck Cab Heater (non PTC)
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