Solar Powered Greenhouse Ventilation

Image: 
Exclude from the Tools list. This is "sandboxed".: 
Wiki Editors: zepickens (7 edits)
Solar-Powered Vent Openers Fan Housing Installing Solar Panel

Basic Information

Because we are in transition, we will be starting seeds for Riverpark Farm in my personal hoophouse. The hoophouse measures 10' X 20' with a 90” Diameter hoop. The space is big enough to do the work I need, but isn't a perfect seed-starting location. I don't have any electricity on-site where I could power exhaust fans or circulation fans, which are crucial to successful seed-starting in transitional weather. Additionally, as the hoophouse will largely be unattended while I'm at work during the day, the system must be automated. It would be nice to have an automated emergency warning system in place if the system fails and temperatures rise to dangerous levels.

On February 11, a group from Farmhack NYC met to discuss the plan and think about ways to design a simple automation system. I am currently working with an electrician to decide on the best fan for the system and then sourcing a solar panel accordingly.

Specs

-See Diagram for dimensions and endwall design layout
-Total of 1042 Cu. Ft. needs to be ventilated. Any fan should rate at 1,563 CFM or stronger.
-Hoophouse gets full sun and I have adequate access to water

Working Design Layout

-Windows will be opened with Solar Powered Vent Openers, inexpensive and self-contained
-Solar panel will be wired to two DC-powered fans. Internal fan for air circulation will be wired directly to the panel. Exhaust fan will be wired to a switch (like a mercury tilt switch) connected to the windows. When the Solar Powered Vent Openers engage, they will close the circuit, thus powering the exhaust fan.
-Do not need a battery for power storage, as ventilation will only be needed when the sun is already out.
-Windows will be installed on the front end wall in existing cavities, built halfway up the frame, like a dutch door.

Materials:

-DC-powered Exhaust fan with louvres
-DC-powered circulation fan for good airflow and soil/plant health
-Switch, like a Mercury Tilt Switch
-2 X 4 or plywood for framing out the fans/ventilation windows
-Hardware for affixing fans and vents
could be hinges, plumbers tape, straps, etc
-Solar Panel big enough to power it all
-Wiring Hardware
-Screws, etc

Tools List:

-Tape Measure
-Hand Saw/Circ Saw for 2 X 4s
-Sawzall if framing fans in plywood
-Cordless Drill
-Electricity/Wiring Specific Tools?

What I Need from This Farmhack

-calculating how many watts of power we need to run the system, what kind of wiring is best for this wattage, how to properly wire it all, etc. I'm not an electrician.
-thinking about the most efficient way to ventilating the space
-designing how the vents/fans will be installed/hung
-sourcing inexpensive/repurposed materials, ex. Maybe using an old home thermostat instead of an expensive new greenhouse one

Other Related Farmhacks

An idea post I authored about passive solar heating for greenhouses
FIDO Text Monitoring of Greenhouse
Solar Double Layer Inflator
Solar Powered Chicken House

I'll be posting as developments are made!

Information

Posted on 2014-01-01 18:17
Posted by meredith848
Posted on 2013-02-07 16:25
Posted by zepickens
Posted on 2013-02-01 13:15
Posted by michaeljamesmeier