I suspect the added cost/environmental cost of adding a slightly more complicated setup than panel <-> fixed resistor, such as an mppt would be a worthy tradeoff.

I understand the point of the blog is to reduce the inputs to simplify, especially in eschewing batteries, but I suspect the loss in efficiency of not tracking the max power point would be significant.

I do like the concept though, in terms of shifting heat from daytime to later in the day, and localizing it into a box, rather than heating your whole house. It feels like the kind of thing you would put in your bedroom to help keep it warm into the evening.

There’s a couple online if you look around, but they’re all pretty small: Opire.dev oss.issuehunt.io/issues Boss.dev/issues/open And probably dozens more

And as a cautionary tale, look what happened to bountysource