Dumping PV into PTC heating elements

[moosemaster]

Thinking of a simple way of cooking direct with PV in the summer - ie, DC, no batteries or inverters. This concept seems simple and scalable.

Envisioning something pretty scaled up - using around 3kW of PV.


Considering using PTC elements. Here is a catalogue with some basic information on them. They negate the need for a thermostat which is handy.


Struggling to wrap my head around how PTC performs when hooked up to PV. I am aware that traditional resistive elements require impedance matching - and ideally MPPT controllers to increase efficiency. With PTC elements the resistance increases as the temperature rises.

I've tested this on a small scale with a 60w panel and 12v PTC element. Gets up to the set temperature pretty quickly but I've no real means of ascertaining the efficiency.



It was this little cooker that got me thinking - according the manufacturer it uses around 85kWh/week which I can match in Summer with PV.


Construction something a bit like this perhaps -

- Build a Domestic Brick Oven - http://heatkit.com/html/bakeov11.htm


Here's a small example of the same idea...

 

[Lucien Nunes]

Don't forget to use DC-rated control gear suitable for your full open-circuit voltage. E.g. an ordinary micro-break thermal cutout might turn into an incendiary device itself if it ever tries to break a load.

 

[moosemaster]

Don't forget to use DC-rated control gear suitable for your full open-circuit voltage. E.g. an ordinary micro-break thermal cutout might turn into an incendiary device itself if it ever tries to break a load.

Absolutely - thanks!