okay one more wacky idea to heat a greenhouse

So I got to dreaming about how hot greenhouses can get and i thought.....if i put tonnes of big rocks into a double walled greenhouse and sealed it entirely without plants inside....how hot would it get? or a big pool of water and a mix of big rocks in the water and in the earth......my assumption would be you could then remove a tonne of warm air out of that greenhouse at night and maybe funnel it into another? or into your living space/house? any thoughts?

Rock beds have been used in many solar designs. A big pile in a greenhouse would not get hot enough during the heating season to provide much heat. Typically, the insulated rock storage is fed hot air from a large area of flat plate collectors. A pile in a greenhouse will radiate much of that heat back to the sky.

I bought and built one of these Phoenix Solar Sheds. I added 2" rigid foam insulation on all the walls and underneath the floor panels. I put in three 55 gallon steel barrels full of water as thermal mass. On a sunny day in the dead of winter, I can expect the temperature to get to about 80ºF. The water barrels will warm up to about 65ºF. Then at night, I've seen the outside temps drop to around 25ºF but the barrels stay around 50-60ºF and the air inside the shed never drops below 40ºF.

Tim, have you looked into "Climate Battery" at all? There are a number of terms floating around, including "Passive Annualized Heat Storage" "Passive Annualized Solar Heating", "climate battery". CRMPI uses the "climate battery" term and has utilized the concept in their greenhouses, with apparent great success.

I think the theory underlying all of the different names and the varied implementations is sound and have every intention of utilizing it when I get to building my homestead.

Hey Peter, I researched climate battery and passive annual heat storage but It seems like people use electricity to run the air pump.

I was just imagining a terraced hillside with greenhouses going up where the air intake from the lower greenhouse is heating the soil above it, and i suppose a way for the cold air to flow out the bottom too.
That would truely be a passive system.....what do you think?

And what would happen if you burried an air pipe all the way up to the top of a big hill and had a greenhouse at the bottom. Wouldn't the hot air want to be sucked out like a vacume? and you can just open and close the air outtake with a wax expander mechanism....

This thread https://permies.com/t/31249/solar/Fresnel-Lens-Intense-Solar-Power may provide some answers to heating a greenhouse.