How to Build an Off Grid Solar Greenhouse

Solar Greenhouse
Solar Greenhouse

Off Grid Solar Greenhouse

We built an off grid solar greenhouse because we live in a cold climate. There has been snow fall that decimated our early plantings more years than not. It is also known to have early frost that ruined our crop before the first harvest. This makes it really hard to grow enough food for a family of nine.

Our solution was to build a greenhouse that would keep seedlings warm and protected until we could safely move them outside. We can grow a few things through the winter also. But we didn’t want to run power to it from the house.

The first step is to decide where to place the greenhouse and design how big you want it. Ours is 8 feet by 10 feet. It is in the sunny corner of the yard. This is where the snow melts the earliest each spring, and where it gets full sun all day in winter.

Building the Greenhouse

I’m not a builder, well, I wasn’t before now. I learned how to do this on the fly. First, I searched and searched for the perfect kit to buy, but they are so expensive. I finally searched for DIY ideas and came across a site with free building plans (My outdoor plans), settled on one I liked that looked easy and went for it.

I found the plan I wanted, printed it, and started to price lumber. The total cost of this 8×10 greenhouse was under $1000.00 including all of the sealants, screws, shelves, and the plastic for the outside. I could not have bought a kit this nice for the same price. I got to customize it to my style and liking too, another limitation of kits in a box.

Just wait till we build the next one! I am going to go for a different style and make it taller so that small trees can be kept in there. It just takes some math to figure out how much of the plastic sheeting you need. To calculate area, you multiply height and width. For example, the side walls are ten feet long, and each panel is two feet wide, so it takes 5 panels to cover it. Then for the roof, you calculate the ten feet by about five and a half for each side and count how many sheets you need again. Sorry, I just have a knack for figuring out those kinds of things. It’s a 3D orientation in my brain that allows me to picture it and do the easy math.

This was definitely a weekend project. We headed off to the big box store after work one evening and had the frame standing before Sunday. Adding the plastic sheeting was just another afternoon. The pallet bottom and top pieces were added during the week the kids helped a ton there due to homeschooling like everyone else! Shelves along the sides and insulating the bottom from wind and snow were added last and then we were ready to move our indoor starts out to their new home.

The Possibilities are Endless

Now that it’s built, what is there to grow? Literally everything! You can use your greenhouse mainly for seed starting and keeping plants through the winter, or you can grow all year long in it!

Want to get your garden off to a great start? Here’s some awesome tips. Not sure what grows best in a greenhouse? Well, we’ve got you covered there too. Some plants are better suited for greenhouse growing than others. Here is a list of those that do well in a greenhouse.

Making it “Off Grid”

To keep things warm in the winter we incorporated a water feature as thermal mass. It’s a simple horse trough fishpond that I’ve had for years. The black plastic helps absorb what few sun rays come in during the winters, and the water retains the heat into the night.

Filtering this pond is the “solar” part of the “off grid”. We simply made a pond filter from a trash can and set up a simple solar panel and battery to run the pump. Check out the filter set up here, and the solar set up here.

Pond inside Greenhouse
Pond in Greenhouse

There were tons of rocks around, so we used them as thermal mass for the floor. The sun, the warm water and the rocks keep the temperature above freezing all winter long! This is how we are able to get a jump on our short growing season.

More great Ideas

Grow your best garden this year with these other fantastic tips and ideas: