Nathan - Electricity from PV (or other source) is not required but desirable, depending on your goals. PV electricity offers many uses, if one can afford a system, or aquire used PV panels, or individual PV-powered appliances. Need/benefit from Fans, heaters, grow lights will vary depending on the month, amount of shade, and level of weather conditions. Bottom heat is great for success in propagating lots of types of plants from stem cuttings (roses & shrubs) and leaf or tip cuttings (lots of house plants). Heaters use a lot of electricity however, so I may not attempt electric space heating for winter. Instead, I'll probably use passive and manual methods to improve my growing in Spring and Fall...and see what might winter-over from basic protection & passive solar storage. I'm familiar with creating cross-breezes from living in good old houses, so the first season I''l see If i can get by with that. My housemate will also let me try his inexpensive Solar Fan before I Buy my own. After buying a nearly useless one years ago, I'm a bit skeptical about the brightness of Solar Lights. So electricity from the house, or PV, might probably make sense for lights. You can use a light bulb below flats as a cheap bottom heater for flats and cuttings; and use water filled jugs to absorb and store passive solar heat for a modest season-extender. A few degrees of comfort can make a difference for some plants. Many plants won't germinate until the soil is 50 degrees, others need over 70 degrees. Bottom Heat alone can start some heat-loving seed varieties. Many seedlings stall out in the Spring until they get a couple days of hot weather -then they take off and really get productive. Affordably accelerating the next growth stage is a goal, even if just for some plants, for Spring--only Season-Extending Greenhouse gardeners. Extending the Harvest by keeping Tomatoes and peppers going in the fall is wanted by others. maintaining the day-length that makes ripening happen can be extended using Solar Electricity. Most seeds can get going just fine outside using Winter-Sowing (see the WS Forum) But especially in cold climates, getting Heat-loving veggies like tomatoes, basil and peppers going months early is often the happiest reason to have a greenhouse. To start everything earlier, and prevent the usual spring-stall-out of growth, and increase odds of survival, using light bulbs or electric heaters can make a real difference. (I assume Fans are desired because air flow, light and & ventilation reduce fungus and mold from humidity...and wind makes stronger stems, and can quickly help cool an accidentally overheated greenhouse) In some regions, seedlings started outside can get brutally pummeled and ruined by rain and hail. Then there are the critters and slugs, that go after many smaller seedlings. Calamities can affect success inside the GH too, but the goal of having micro-climate-control equipment is to selectively reduce the risk. In areas where the Spring keeps you indoors feeling gloomy, working in the GreenHouse can lift your spirits. I plan to bring Springs of fragrant herbs in to add to that experience. In Winter/early Spring you need light both for heat/comfort and for plant growth. In fall, comfort and continued ripening. Indeterminate Tomatoes can keep on setting fruit too...so they'd be a better choice than determinate Toms. Some Gardeners use their GreenHouses 12 months a year, for food, orchids, african violets and many other plants. In cool and cold climates, adding insulation, electric heat, and light sources makes this an option. I'm a newbie to Greenhouse growing myself, but have been getting ready to get mine by reading about it for awhile. I have just enough experience with failed plant experiments, stalling after WinterSown sprout success, and Slugs during hardening-off to appreciate the possibility of greater success another way. So I might use a combination of Passive and Photo-voltaic Solar-options in my new GH. I intend to use a cheap thermometer and manually adjust shade to keep seedlings from getting cooked. I really like the idea of allow Cukes to grow up a wire frame to provide some natural shade in season. PV-assisted light inside, on a day-length adjusted timer for optimum growth and ripening would be wonderful. My personal challenge will be to keep (seed-drying refer to the thread: Seed-Saving Nutcase) and other non-growing stuff OUT of the GH. Remember: the new GH is NOT a Shed or granary! Hope this summary helps someone think through their GH choices. Jules

Hi Cole. After talking with several people, that have used the black poly pipes for hoops, they said they did not have problems with them getting too hot. As far as your observation on my evaporative cooling system goes, I think you are not familiar with how an evaporative cooling system works. It is strictly a pass through system. It is not like a recirculatory refrigerated cooling system where you are trying to seal a place up as tight as possible, and the same inside air is recirculated through the cooler over and over again. You must have constant air flowing in and out of a house for an evaporative cooling system to work. Here in the south everyone used to use evaporative coolers to stay cool in the summer. I used one for years myself. The way my cooling system is designed to work is basic science. The exhaust fans will exhaust the hot air which is rising to the top of the GH and this will cause a vacuum which will pull air in from any available hole. I have sealed every hole possible other then the evaporative panels, so the large majority of air will entering through them. The air that will enter through the evaporative panels will be a lot cooler then the air inside the GH and will naturally fall (hot air rises, cold air falls). This cooler air will settle along the ground of the GH keeping the plants cooler. As this air heats up it will rise to the top and be replaced by the cooler air coming in through the panels. You see, the exhaust fans will never be exhausting cool air, this defies the laws of physics. The object here is not to create a uniform temperature inside the GH from top to bottom, but only to keep the lower few feet cooler. When I say cooler, I do not mean 50 degrees here, I mean less then 100 degrees (hopefully around 90 degrees). In the end, I will end up with a temperature difference inside the GH. The upper air will be hotter then the lower air. There is no question here that there will be a temperature difference. The question is, how much of a difference it will be. Will it be 5 degrees or 30 degrees. There are too many variables involved to calculate this now, so I will just have to wait and see how it goes and report back here with the readings when I get them. Unfortunately, this will have to wait until next summer. If in the end, my system proves to be ineffective at keeping the lower part of the GH cooler, I will go back to the drawing board.

Kevin...Now I see a huge inside tree....That looks awesome! Looks like you have been deriving much help here..Yours trees look remarkable for growing indoors up here and so fun, right? I have over about 30 and I am about to cull a few..Getting tired of too many trees and not enough room or time..lol There come a time when one looses as many trees as we buy, and therefore we keep buying more. Then once we get really good at it, we keep buting more thinking we need a few of the same kind and yet they live and live....I have yet to loose one as they keep getting bigger and bigger and more take up space...I never get confident in myself so it keeps me buying, but they live and flourish..It's never ending..haha.. Before you know it you will be installing greenhouse and solar ceiling to create more ideal conditions and room..It's a sickness I tell you...lol MIke

. We all need to realize something: EVERY thing we do has SOME impact on the place we call home. NO form of energy is free of that condition. Mining coal, drilling oil, splitting seawater, PV panels, whatever . . . they ALL produce some impact; not only in their "manufacture" or procurement, but also many WHEN used, and many AFTER they are used. Nothing is exempt from that. Once we all realize AND accept this, it becomes very obvious that there are two things we can ALL do to minimize our impact / extend the useable life of resources we have. First: Minimize energy we use no matter where it came from . . . insulate better, drive a different vehicle if you can, walk, take a bus, wear a sweater . . . tons of little things we can all do . . that don't really change our lives, just make it a little different. Easy to do if you feel the need to. Second: Use energy forms that cause less overall pollution / consequences by their very nature. Dirtiest ones should be avoided at all costs if possible . . nukes, coal, oil . . all produce some signifigant impact on a large scale . . acid rain, trace heavy metals, waste we have NO idea how to "dispose" of. Wind, PV, hydro power, biomasss ( ethanol, methane ) . . all produce consequences too . . but can all be relatively easily mitigated / minimized. And they ALL can produce more energy than is consumed in "making" them. One investment initially; and these things can produce lots of power for many, many years with virtually NO further consequences. Brazil and ethanol . . I don't have many facts about it; but did hear about it many years ago. An amazingly good, simple idea from a "third world" country. They had FAR more insight into the big picture by proposing such a thing than any administration here could ever think of. Believe the whole premise was to use sugar cane tailings that result from the existing sugar industry; to ferment into alcohol. Using an existing " waste " product to produce fuel / reduce need for oil. An investment ( energy-wise ) into the equipment etc once; can "produce" lots of energy for years and years using what is now "garbage". If you think about it, the "source" of the energy in such a process is . . . solar. Sunlight / photosynthesis turning water / CO2 into sugars etc; which ferment into alcohol very easily. Not unlike making wine / beer. Not only that; but alcohol is a very simple compound . . under realistic conditions can burn quite cleanly . . unlike the chemical "soup" that existing gasoline is . . producing all kinds of compounds in the burning process. So what makes things such as Brazil / ethanol happen ? ? ? Mandates via gov'ts / laws. I'm no fan of them; but if they do not produce such changes; the changes will NOT happen. There's more money to be made drilling for oil than fermenting garbage. THAT is the bottom line in determining energy policies / sources . . not the environmental issues behind them . . . Believe it was a Canadian gentleman who said: " If the people lead, the leaders will follow." . .. . think about it . . . Bob