That is just simply amazing! They seem so simply built. I learned about these types of structures several years ago, I wish I could find a location to build one. Jay Here is a link that might be useful: More Chinese Greenhouses

I find this very interesting. I am a novice at both gardening and the art of season extension. I had never even read the packaging on a solar panel until last summer so I am floundering with this technology - but it is so much fun. This is like tinker toys for adults! I have a small 6 x 8 palram polycarbonate greenhouse. It sits on a deck. I created a trough inside the greenhouse using 2 x 6's, a rubber liner and then topped it with leftover ceramic tiles that I had so that this square footage was still usable for plant placement. I then made myself a solar water heater with pop cans, paint, pvc, plastic, wood and which originally worked using thermosyphoning but I considered that too slow a movement so I added a small water fountain pumps run by a solar panel. It is direct connected - no sun, no heat, no movement. Sun out, the water circulates to heat up the trough. It is not a huge gain, but I don't pay for any energy to run this spring throughout the fall. I have bought a deep cell battery and have additional solar panels set up in preparation to store energy for after sundown use - not to operate the pump, but for lighting or to run an ozone generator from time to time. I did try to insulate some for the later fall season using Johnny seeds bubble stuff but there wasn't much use to this. I do have a natural gas heater but shut it down for February and most of March because my GH is too leaky and I see no reason to pay to heat the outdoors. I will take you advice and do a better job of sealing the GH this year. I am also building a cold frame and will be making bases for two small pre-fab cold frames. I plan to have these completed by the end of next week. Our ground is still frozen so I won't be able to properly prepare the area for these to fit over for maybe another few weeks. I am champing at the bit. Come on thaw! Thanks for sharing your ideas with us. I will be looking forward to your posts.

A few thoughts: 1. What will the framing be between the layers of PC? If wood, then you may have issues with moisture and eventually rot in there. 2. If you can, keep track of the outside face of the PC when you remove it. Typically only 1 side is UV protected and needs to go on the outside. 3. If the PC is getting brittle now, it may be nearing the end of its useful life. Just something to keep in mind. 4. I tend to agree that some sort of supplemental heat will be needed if you intend to keep the GH above freezing in the winter.

Mike, in my post I said I did not use my lights to 'grow' plants, I said I use them to provide 'short night' response in my photoperiodic plants to postpone their bloom times. For that, I don't need 2K foot candles, I need 20 foot candles. For the purposes of determining the quantity of light your plant is actually getting you can't just spit out the wattage or lumen rating output of a bulb as rated on its package. For instance, a hundred watt, unshielded incandescent bulb, ten foot away from an object will only provide about 1.5 foot candles as measured at that objects surface. That isn't much, is it? So, you can't just say a lamp has X lumens and have that mean much of anything. That's the potential output of the bulb. What you are interested in are the readings at leaf level, measured in lux or light density and that is going to vary greatly depending on how far away the light source is, what design the reflectors are, angles, intensity at various points of the cone of the beam. Yadayadayada. And if you think you are actually doing much trying to supplement the natural light by hanging a few shop lamps from an overhead beam in a greenhouse with a flourescent tube in them............well, it's not going to hurt anything, but it probably has negligible actual benefit to the plant. So, if you are really needing to provide lighting by which a plant will actually grow.........then your supplemental growing light has to be quite close to the plant, or the output has to be considerably higher than you think if mounted from overhead beams. The only way to really tell is to meter it out at various points in a greenhouse. That's why I suggested the poster find out what intensity of illumination leafy veggies really take. If she/he can make do with natural light, it would save a lot of money, and I suspect they'll grow just fine without supplementation. That's why in all but special circumstances where high light levels are absolutely necessary for producing certain plants in a winter setting, most growers do not go the expense of installing supplemental lighting. It's expensive to install and it's expensive to run, unless you are just interested in starting a few seedlings or a very limited collection of conservatory plants.