Tiny Tuesday: What the Solar Tariff Means for You

If you’re planning to install solar panels in the near future, it might cost you more than you expected. And if you work in the solar industry, you better have a backup plan.

On January 22 the Trump administration announced tariffs on imported solar cells and modules for the next four years. (A solar cell is a single semiconductor that converts light into electricity; a module is a sealed series of solar cells. A solar panel combines modules with a frame for installation and hardware for wiring.) The tariffs start at 30% the first year and drop to 15% the fourth year; the first 2.5 gigawatts of imported cells each year are exempt.

According to Solar Energy Industries Association (SEIA), the US installed 12 gigawatts of solar in 2017. Roughly 80% of solar cells installed in the US – that’s 9.6 gigawatts – are imported, mostly from Asia. Imagining for the moment that installations stay constant, 7.1 gigawatts of solar will be subject to the 30% tariff. Averaging this tariff over the total 12 gigawatts installed means an 18% increase in cost for solar cells across the board. Distributers will generally pass this cost on to consumers.

But in reality, basic economic theory tells us the cost increase will depress consumer demand for solar panels. In particular, companies that procure and install solar panels will take a hit due to declining customers. SEIA estimates that of the 260,000 solar jobs in America, 23,000 will be eliminated by the end of the year.

On the other hand, there are signs that the tariff will achieve its stated intent – to encourage domestic solar manufacturing. Before the announcement, foreign solar cells were clearly cheaper than American-made cells, in part because of low labor costs, but also because foreign governments subsidize the product. The tariff levels the playing field.

Chinese company Jinko Solar bore this out last week by announcing its plan to build a factory in Florida. This factory aims to build 1.75 gigawatts of solar modules over three years, all of which will avoid the tariffs. The profits from this venture will go to Chinese soil, but nevertheless the plant will employ Americans. Other foreign companies may follow suit. So it’s not all job losses; jobs will be created as well.

Solar installations will decrease; solar manufacturing will increase. In the short run, we’ll need to pay more to get our electricity from the sun. But we have a strong national trend toward clean energy, the Trump administration’s indifference notwithstanding, and I predict that in the long run we’ll come out ahead.

Tiny Tuesday: “Energy Nerd” Advocates Build Small

Martin Holladay has been building houses on the cutting edge of energy efficiency since 1974. A Vermont native, he’s now a senior editor at Fine Homebuilding Magazine and Green Building Advisor. Holladay records his latest thoughts in a weekly blog titled Musings of an Energy Nerd.

A reoccurring theme in Holladay’s work is his conviction that Passive House principles are overkill for most homeowners. Holladay argues quite convincingly that a small house will burn far less energy (and money) than a big house even if the latter has R-60 walls with triple-glazed windows and an HRV. He advocates for what he calls a “Pretty Good House,” which focuses on air tightness and mindful energy use, eschewing other Passive House standards like 14-inch-thick insulation under the floor slab. He has a special disdain for huge south-facing windows, which leak far more heat than they gain through the passive solar mechanism.

On the other hand, Holladay is a fan of minimizing embodied energy (plastics and foams are popular but their manufacturing carries a lot of hidden environmental costs), maximizing onsite energy production (especially PV panels), and designing footprints and roofs as simple as possible to save construction costs and problem spots. In so choosing his battles, he has made the “Pretty Good House” a mashup between a passive house and a net-zero house. The emphasis is on keeping money in your pocket. I think a lot of homeowners could get behind that.

Tiny Tuesday: Net Zero, Affordably

Dave Posluszny designed and built a net-zero house in Massachusetts from an existing foundation. No fossil fuels are used to power the house: HVAC and electric all come from solar panels on site. Posluszny aimed to make the house inexpensive (not commonly associated with net zero, at least up front) and easy to build, which led to some unusual details. Green Building Advisor shares this article he wrote about the design, and it’s worth a read to understand his decision-making process.


Vapor barrier, WRB, and thermal break at the top of the leveled foundation wall.

One detail actually generated a disclaimer on the article and much discussion in the comments. For his the water-resistant barrier (WRB) on the wall sheathing, Posluszny used Ice & Water Shield, which is also impermeable to vapor. This detail results in what some builders call a wrong-side vapor barrier, located outside the insulation instead of inside, which threatens to trap condensation in the walls and cause mold. Posluszny claims there won’t be any vapor to trap because the house is airtight and properly flashed, but a lot of builders feel uneasy.


The entire house is wrapped in Ice & Water Shield.

Posluszny describes several other unusual but logical decisions he made. Instead of making the insulation better (at a cost of square footage and budget), Posluszny opts to just install more solar panels instead. A roof vent above the scissor truss was accomplished with two layers of sheathing in order to place the WRB on the underside. The house has few windows, which is very smart from an insulation perspective; a semi-gloss white paint on ultra-smooth plaster ceilings brightens the interior.

I applied this thinking to all my decisions, and found that the least expensive way to be net-zero is not always the most energy-efficient way.
–Dave Posluszny


Open floor plan, showing one of the two lofts.

BONUS! Here is a glossary of the four barriers a house requires to maintain the temperature and humidity inside – in other words, to keep you comfortable.

Air barrier: The layer that prevents ambient air from entering the building, or conditioned air from leaving it. The sheathing usually serves as the air barrier, but builders need to be religious about filling in accidental holes (with spray foam, perhaps) in order to make a house completely airtight.

Thermal barrier, aka insulation: The layer that prevents heat from moving in or out of the building. The thermal barrier defines the building envelope. A conducting material that passes through the thermal barrier is called a thermal bridge, which wastes energy and should be avoided.

Vapor barrier: The layer that prevents water vapor in the air from entering the building. Exterior-grade plywood, plastic or aluminum sheeting, or Ice & Water Shield may be used as a vapor barrier. (If the house has a perfect air barrier with no holes, then the air barrier also serves as a vapor barrier.) Installed incorrectly, a “wrong way” vapor barrier may trap water vapor in the walls, leading to mold.

Water-resistant barrier (WRB), aka drainage plane: The layer that keeps rain and other liquid water from entering the building. Most houses use felt paper, also known as housewrap, but this house uses peel-and-stick Ice & Water Shield, which doubles as a vapor barrier as described above.