Although I do not own a solargem, I have seen several in operation. The heating part is fairly easy, as you mention, disregarding the energy costs. The larger problem will be cooling during the summer months. The ventilation system will need modification to allow more air circulation, plus shade cloth, misting, etc.

Fuzzy, it may be time for you to do a "desired lifestyle & available time to enjoy it" check. You built a GH for pleasure. Please don't tell us it was to feed your family, because the simple truth is that building and operating a small home GH is far more expensive than simply buying fresh veggies and if you are into all natural, there are plenty of shops around these days to accomodate you. In fact, you could shop exclusively at Whole Foods and still not spend what it costs to build and operate a small home GH. Ergo: you built it to ENJOY it and unless you are independently wealthy, the TIME available to you to ENJOY it is when you are NOT working to earn the $ it will cost to operate it. So don't get so wrapped up in gadgets that you end up spending as much if not more TIME messing with the mechanicals than you do puttering with plants. Perhaps it's my age, but the older one gets, the more one appreciates TIME- The Great Thief.

The U of MD is certainly worth checking. Our passive solar house with hot water solar was built over 25 years ago & a rooftop photovoltaic system was just connected this past week. In case you haven't done so already, make sure you check for Federal & State tax advantages and state/DC grant possibilities. Also, if you haven't been before and aren't in a hurry, there is a DC metropolitan area annual solar house tour the first weekend of October. I may be able to answer some specific questions.

Hello Gumbootmama, I can't believe this thread has gone on for 2 years. I'm curious to know if your system is working for you. I have a few words of encouragement, even if its 2 years late. It sounds like you will be hooked to the grid anyway so the demands on your 12v system won't be constant. I would totally put it in. The cool thing about a 12v system is you can recharge the batteries from many sources. Solar panels of course. And to be realistic you won't get much recharge on grey winter days, but with most modern solar panels you will get some, and if you're only using the power in emergencies the battery will stay topped up, ready for use. Lights and radios don't take very much power at all and when the power goes down, as I'm sure it does up there, battery backup would be great. You could charge your battery from the grid in the winter if you were using it only for emergencies as well. I find it hard to believe you couldn't get power from a small wind turbine, being only a few blocks from the ocean. Especially in Winter. The only concern there is cost and trees. They typically cost over a couple thousand to install, and you usually have to get them higher than the tallest trees. In your neck of the woods that could be over 200 feet. On more of a theoretical note. You may not have sunshine in the winter, but you do have a huge amount of sun energy stored in wood. There is a way to charge your batteries with wood. You use a wood gas generator to power a conventional gas generator. Its not technology that is used very much nowadays. But its old technology. Half the cars in parts of Europe were run on wood gas generators during the second world war. Its even more appropriate technology for remote power generation, because generators typically run at a constant speed. The chemistry behind it is actually pretty simple, but I'll save our readership from that. If anybody is really curious email me. Another option would be to grow a sugar or starch crop and ferment it and distil it for Ethanol and then run your generator off of that. Corn and sugarbeets might work. I think Jerusalem artichoke might be an option as well. You get 1l of ethanol for every 12kg of artichokes. 2000 sq. ft. should give you about 100 litres of fuel. Enough for the winter? You could ferment and distil in small batches in a greenhouse and the extra CO2 and heat would be a real boost to the plants in the fall. This is what we plan on doing at our place. You could of course just run your gas generator on gas. It would only cost you $100 and save you from growing 1200kg of artichokes. Having the 12v is great though, because you only have to run the generator to charge your batteries, not everytime you want power. Water pumping and refrigeration are the big uses of power. Lights and radios use way less so wouldn't be much of a power draw. One more idea. If you only want power for light and radio, and only in emergencies, you could just use rechargable AA NiMh batteries. They are way less toxic to dispose of then their NiCad predicesors. You can order them over the net at about $2 each or less, and a decent charger will cost you less than $50 with shipping. They can be charged up to 1000 times. You could have 10 or 20 fully charged batteries stashed away. Enough for any winter storm. You can even plug them into your car or 12v system to recharge them, or hook them up to a small 3v solar panel. Search for Nexcell on the net. Good luck up there, Sleepybee