After a slow start with Tesla we got an new account executive who made things fly: Aaron Lopez. With the internet up and working, the way was clear to schedule an installation inspection. Mike Lindsey, decked out below in his safety get-up, drove up from Agawam to check out the situation. Mike's analysis of the SunCottage led to the decision to emplace two PowerWall2s. This is a whopping storage of 28 kWh, on a sunlit day, these two batteries could store the entire day's out put of the sun. The question is, in the event of a power outage, how long could the batteries power the house?

Since we've opted for 'whole house' power (rather than selecting key elements like the hot water heater, pump, etc.), we're very curious as to how much power the house will consume on a daily basis. And we really want to know how much in the winter, since the geothermal heating system needs electricity to draw the warmth from the earth. In the summer we'll have no problem, 28 kWh will probably power the house for a week with no sun. And if it comes out one day a week, it'll be powered forever.

Estimates for winter usage range from 10 - 30 kWh per day. Which means the batteries will provide 1 to 3 days of emergency power. For each day of full sun, we'll get a 1 to 3 day extension. The tough period will be the two months when the sun is low on the horizon, say from November 21st to January 21st. The good news is, that by using the pellet stove to heat the house, we'll dramatically lessen the electrical draw. A few hundred pounds of wood pellets should get us through any tough times.

Comcast & the Internet!

It took weeks to get Comcast to string the wire from the pole at our main house to the SunCottage. But in late January, we finally went internet live. This was key because the Solaflect tracker needs an web connection to get properly aligned, and to send production feedback to the cloud. Additionally Tesla needed to know the internet was connected before they'd send up their man, Mike. All worked out and Jason and the rest of the crew were psyched to have access, both phone and internet.

Here's today's energy generation: 24.68 kWh. Not too bad when you notice that production dropped dramatically around 1:00 pm when the clouds moved in. Also worth noticing is that for a couple of hours in the morning we were pretty close to the maximum energy generation of 5 kW:

( Update: the next day, February 18th, we hit 6 kW! )

UltraGeothermal

The crew from UltraGeothermal out of Barrington, New Hampshire came in like gangbusters and put in the system in in two days. Consisting basically of pumps to transfer the fluid from deep down in the earth (two wells, 350 feet each) into the utility room where it can have its heat pumped into the separate loops that provide radiant heat to the three floor slabs, we pulled the portable electric heaters out on February 10th.

The large black tank at right stores 40 gallons of 93 degree water for use when the thermostats demand it. The gray cube is the actual heat pump that draws heat from the ground loop and returns cooler fluid to the wells to be passively re-heated.

Insulation

We decided to go with spray foam insulation for the exterior walls because of the desire to create a really air- tight house. If you recall, the house was built with 13 inch thick walls. I had assumed that the entire inside cell, that is the full 12 inches, would be foamed. I guess I'm used to 4 inch or 6 inch walls where insulation battens fill the entire space between the plywood sheathing and the interior sheetrock. But it turns out that anything beyond 8 inches of foam provides minimal return on the R-factor. If you look at that chart northern New England is in a region where we should look for an R-factor of 13. Eight inches of closed cell foam (the kind we're using) rates somewhere between 40 and 50! Clearly no need for an additional 4 inches...

Besides being 50% more expensive for really no added return, there's the idea that for the future it might be good to have open space to string wires, cables, or who knows what might be 'the thing' 20 or 50 years from now.

Energy Recovery Ventilation

In January we finally got delivery of the ComfoAir 350 Zehnder ERV unit that will ensure fresh air throughout the winter months. Mike and Jason did the install, the first they have ever done, and it was no easy task. Hundreds of feet of ducting had to be snaked through the floor joists to provide intake and outlet ducts on every floor.

Plasterers

Brian and Dave moved in in February to start plastering. These guys are accomplished workers, or maybe I should say artists. Check out their use of stilts to work on the ceilings. Its a wonder to watch these guys doing their thing.

Cabinet Design

We finalized the kitchen cabinet design this month and Diana sent us a mock-up. Scheduled delivery is April.

Front Overhang

Shawn's overhang is in place, sheltering the 2 ½ thick ProVia door, the most energy-efficient door available.

Hot Tub Platform, Doors & Windows

The support platform for the hot tub appears below:

The fully openable outer doors are installed.

Radiant Floor

Dan is installing the routed out sub-floor that has channels for the radiant heat tubing in the top floor. We hope to cover it over with birch flooring sometime in March.

Springwater

Still messing with the spring water reservoir for the hot tub. Here's 300 gallons of crystal-blue water so good you should drink it rather than sit in it!

Frosty Panels

Sunrise shot of the tracker before the sun evaporates the rime frost:

31) Tesla, Geothermal, Insulation- February '18

Tesla Man!