Steve, when I asked several questions about the Airhead from their Tech dept, Jenny replied with answers. The Solar vent was one of my questions:
Q:I've seen some hook it up to their solar vents. However, there are times the solar vent fan stops working, with cloudy days.
A:We do not recommend solar vents anymore. In the beginning we did. They can let wind in when it gusts. They do not run 24/7 after a cloudy day, and can expose the system to insect invasion. They also do not prevent water ingress. They are designed to circulate air through the cabin but for that application, it was never critical for the unit to run 100% of the time.
I have noticed with my solar vent that sometimes when it's windy out, air does come in. The descriptions on the Airvent 500, non-solar, no fan, one of the recommendations from Airhead, say it vents air with wind speeds in excess of 15mph. It does have a bit different design and I assume that design allows somewhat of a venturi effect. One of the disadvantages I saw with the composting toilet was the need for constant battery power to run it's small vent fan. Even at .06amps, a constant draw without recharging the house batteries would deplete them. I don't have solar panels, but I do tend to keep the boat plugged in even when on the trailer. Or keep the batteries above 60%. With two group 29 house batteries, I could probably go a week before that small amperage draw would be a problem. I do have the small vent fan wired in to my light circuit, and I do shut the master light circuit switch off when the lights (or cabin fans which are also on the circuit) are not needed. But I will probably have to start leaving that circuit on if I want the toilet to be vented. However, it's nice to know that the Airvent 500 is suppose to vent air with a breeze above it. I'm tempted to leave the current setup along with the Airhead vent attached to the solar vent, as I got both fans available. However, with the switch to the solar fan inaccessible now, it's always on and will only run when it's solar battery is charged. However, I guess there is still the possibility of water coming thru that vent? Colby
Here is a photo of the final installation:
And this is a close up of the Airhead vent hose/head attached to my solar vent via a spacer plate.
