Kent,
I believe, IMHO, that temperature control would need constant monitoring or you would cook the sap overly much. I have a passive solar air to air panel (a perpetual experiment) and the temperatures achieved vary wildly. I love the idea, makes a lot of sense, you would just need a way to maximise heat sometimes and reduce it when the Sun is out and the sky is clear. 
3 Likes
Mike, I have often wanted to try an air heating panel in the winter time, but have never gotten it done. It makes sense that an air flow system would vary more rapidly than something with water, but it didn’t occur to me. The simplest thing I can think of is a speed controller for the pump, so you could set an average working flow rate, and a thermostat that would run the pump at full flow if the temperature gets too high. You could add a cross flow air fan that turned on at a little higher temperature, to drop the temp and increase evaporation.
The best way would be a microcontroller to vary the pump and fan speed as the solar input changed. Seems like over-kill though.
4 Likes
I love open source projects like this one where people combine efforts…
If he insulates those lines and deals with the wind he will have a large amount of energy.
4 Likes
The irony to all this is they are taking down SEGS and Ivanpoh thermal electric generation. Ivanpoh never generated as much as they claimed they could. I don’t know about SEGS. Thermal electric was supposed to be the ‘cheap’ way to generate gigawatts of electric when panels were 3 dollars a watt, and there was ‘no way’ PV could be cheaper. We tried it, it didn’t work. PV is actually cheaper now.
I am not trying to discourage you. I always find it a neat project. I had kind of forgotten about Ivanpoh and saw a blip about them decommissioning it. claiming government waste. It really wasn’t, sometimes you have to try knowing sometimes you fail. It shuts up people spewing whataboutism and offering alternative theories.
4 Likes
Ah, yes, Ivanpah. It’s been almost 20 years since we took a bunch of students on a serious field trip out there. It worked okay. Lots of folks involved in keeping it working. To be honest, what I remember most about the trip and the talks is desert tortoises. The State of California was concerned about damage to the tortoise population. The courts determined that ten tortoises would be a reasonable number to kill. Eleven, and the facility would be closed by court order. There were 8 or so paid professional naturalists, required by the state, keeping track of tortoises and other environmental concerns. When we visited, about 7 years into, I think, a 10 or 15 year design life, one tortoise had died. Amazingly, it was backed over by a pickup truck driven by one of the naturalists. I’m no expert, but I think the major design flaw was building it on the California side of the state line with Nevada.
Solar thermal is a nice local product. I can work with paper mache and foil. I’ve worked with silicon, dopants, and aluminum too, but it’s a lot more work, and there’s a lot more to go wrong.
Pardon the topic drift, now back you your regularly scheduled programming.
8 Likes
If it were not for rabbit trails, I would not be here, so feel free to go off topic 
3 Likes
Charcoal + solar cooking… interesting…
3 Likes