We have 14 systems in mind (PV, geothermal, Trombe wall, thermal mass, etc.) to integrate into the SunCottage and get it to meet our goals. First and foremost is the photovoltaic system. We chose to go with a mobile tracker that follows the sun:
The Solaflect company is located in Norwich, VT so very local. It was founded by a classmate of mine in the class of 1978 at Dartmouth, Bill Bender.
We primarily chose this tracker because by moving the panels perpendicular to the sun, it yields 40% more electricity per solar panel.
A tracker can produce up to 40 kWh of power on a cloudy day. To put in perspective our main house uses approximately 30 KWh per day. Our estimate is that the SunCottage will use substantially less. We'll have efficient lighting, a heat pump hot water heater and fewer electronics, which use an amazing amount of electricity when you look into it.
The big unknown is how much electricity will be used to run the heat pump geothermal heating system. I read an estimate out of Halifax that quoted 19 kWh if your heat pump runs 80% of the time. So, on sunny days we'd be in good shape to cover all the electric needs of the SunCottage.
Solaflect has an interesting page online that records the daily output of their tracker located behind Baker Library in Hanover. Check out today's energy production:
Kiosk Data from the Dartmouth College Solar Tracker
Our plan is to install a Tesla PowerWall II battery. Which can store two to three days worth of electricity to power the SunCottage in outages. With reduced power consumption and average sunshine, the aim is to be able to be capable of being off-grid.