hmm, if you are wanting a hydro setup you may need someones elses advice on that, i'm an organic grower, I have grown hydro before but I am nowhere near an expert on the subject, also you can grow a harvest outside with only natural light, but you'll get small nugs, and it gets cold in sac-town, even in a greenhouse, consistent temps in the 30s and 40s will stunt them, and couple that with the short day and you'll get small nugs and even further you will always have an issue with humidity without fans, the temp difference of a greenhouse and the outside will attract moisture, like your car does at night.
A greenhouse is golden if you can regulate the lights, but then its a gigantic beacon for thieves and/or law enforcement if you aren't legal, you are in CA so I assume you are 215.
Personally i'd do a soil, organic setup with a light to extend the day cycle, I understand that isn't easy for some.
Just keep in mind a harvest done in the winter (with no xtra lights) won't net you much, and you may lose it all in a rainy week or two... can't dry the air in a greenhouse... especially with no electricity.