Monthly Archives: November 2014

Just in the Nick of Time

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The new solar array, powered up (and nearly invisible) just as the first snowfall begins.

And… we just powered up the new solar system. 10,000 watts of solar, feeding into the grid. Though, quite a bit less than that at this very moment, because it’s snowing hard and the snow is piling up. So, I got the project (mostly) completed just in the nick of time. I still have some inside work to do with the water heater (post: “An Efficiency No-Brainer“), and a few odds and ends here and there, but the bulk of it is finished. Some photos of “Phase Two”—

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Thirty-six Enphase micro-inverters. Each panel gets its own inverter, and feeds 220-volt power into a trunk line, and from there through a meter and into our main sub-panel.

 

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Step one– putting up the rails.

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The rails are held to the roof with brackets that are attached with 3 1/2- inch lag screws. I got lucky with the purlin spacing, and only had to add one, the new wood is visible here. I also had to add an extra block of wood under each bracket to give the bracket screws enough material to grab onto. Each rail had 11 brackets, so that meant 66 blocks that had to be added. It took a while; I was glad when I had them all in.

 

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Our interim power solution while we were between systems, two Honda 2000-watt ultra-quiet generators, tied with a patch-cord to combine their outputs. The 30-amp plug is tied through a transfer switch inside to the load center in the house. Our biggest load is the well pump, which appeared to draw 2300 watts. One generator is mine, the other is my neighbor’s; he was gracious enough to let us borrow it for a few weeks. This setup proved quite flexible– we could run one generator, or both, or one and not the other, depending on how many loads we wanted on. The generators also idle way down in “eco” mode; better than listening to a large generator yammering away.

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Midway through the roof work, Green Mountain Power came and pulled the power in. Here’s the transformer cabinet in front of the barn.

 

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The combiner box. Each row of 12 panels feeds a trunk line that ends up at one of these 220-volt breakers. From here the combined power of all the panels feeds into the solar meter.

 

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It turned out to be easier to bolt up all the invertors before the panels. High winds were hampering my panel installation efforts, anyway.

 

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The “Sola-deck” box flashed into the roof. The three trunk lines terminate here, and are tied to THHN wire to go through the conduit and down to the combiner box. It is also possible to use the Sola-deck box as the combiner, but we didn’t wire it that way.

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Finally, a nice day to install panels last Sunday. I worked non-stop and got nearly all of them up in one day. I made a jig to hold each bottom panel while I connected it. There’s probably a better way, but I was working by myself.

So, the bulk of the project done. Each inverter reports data to the internet; I’ll keep track of the input. If all goes well, we’ll be powering the house and the cars and still have some left over. Material for a future post…

An Efficiency No-Brainer

 

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An attractive photo for an important but visually mundane topic…

This post is about water heaters, but I didn’t think a photo of a water heater would garner much attention, so I opted for the pretty-woman-in-the-shower picture. The news here is important, though, and worth attracting some attention—in the last few years heat pump technology has made two areas of household energy use dramatically more efficient. One of those areas is space heating, with the advent of affordable and highly efficient cold-climate heat pumps (also known as “ductless mini-splits”), and the other area is water heating. Heat-pump water heaters are now available that are two to three times more efficient than standard resistance-element heaters, and could save the average family $300 a year or more. As one would expect, they’re more expensive than standard models, but heating water is one of the larger energy demands in most houses, and because of this the units can pay for themselves in just just a few years. And after they’ve paid for themselves, it’s money in your pocket every month, and far better for the planet, too. Like I’ve said before, efficiency really is the goose that lays the golden egg.

There’s a short video on this Consumer Reports page that gives a good overview of these heaters. Basically, the units use heat pumps, similar to those in refrigerators or air conditioners, to pull heat from the air and put it into the water, and this takes only about a third as much energy to accomplish as creating that heat with a resistance element. Now, while these heaters are probably a wise investment for the vast majority of homeowners, there are a few factors to be aware of before deciding to make a switch. Among them:

— The heaters produce dehumidified air as they operate, which is a side benefit for most people. But, unlike a standard water heater, they need to be installed where there is access to a drain for the condensate to drip into.

— The units are a bit taller than standard water heaters, because the heat pump portion typically sits on top of the tank, so you need to have space for that. Here’s a picture of the Whirlpool model I bought as part of my current net-zero project, and you can see how it’s taller–

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— Because heat pump water heaters pull heat from the surrounding air, they operate more efficiently if they have a bit of extra space around them. In most installations this isn’t a problem, but if your current water heater is in a very tiny closet, it might be an issue. Related to this, they cool the air around them as they operate. If you live in hot climates, then this can be another benefit. In colder climates, you might see less overall efficiency gains in the winter if the building has inefficient space heating, and the water heater forces that system to work harder.

— Because the price of solar PV panels has come down so dramatically, it is now cheaper to heat water with a heat-pump water heater and electricity from PV, than it is to install a thermal solar water heating system. This path to hot water requires far less maintenance, too.

— The units do make some noise, unlike standard electric water heaters. I don’t have mine installed yet, but the water heater we’re replacing is a direct-vent propane model, which has a blower fan, and I actually expect the new one to be quieter.

So, these heat-pump water heaters might not work for everyone, in every situation. If I had to generalize, though, I’d say that the vast majority of everyone out there with a standard resistance-style electric water heater could come out way ahead by switching to a heat pump model. For those people who get hot water from a fuel-oil furnace, it might enable them to turn off their furnace in the summer, when they might otherwise have to keep it running. And for people who heat water with natural gas, the units might not save enough to pay for themselves. Though, if you could switch from natural gas to heating with renewable electricity, then it would still be a big win for the planet, even if your pocketbook didn’t see a difference.

I know two people right now who have switched, and both seem to be thrilled with the performance of their new models. I’ll have ours in soon, and I’ll do a post about it in a month or so.

Copyright: choreograph / 123RF Stock Photo

A Little Hardship is a Good Thing

I’ve been working pretty hard, physically, on the project, but I feel pretty good, health-wise. Some periods of hard physical labor, I think, are good for a person from time to time. So, reflecting on this, it occurred to me on the drive to work this morning how much physical labor is NOT in our modern lives. We turn on the faucet, and water comes out, no more hand-pumping or carrying water. We take a few steps to our vehicles, no more walking, no more saddling of horses. We hit a button and the garage door pops open, no more doing that manually. We go through the drive-through lane for some breakfast, no more cooking, no more getting out of the car. Heck, we don’t even have to roll the car window down anymore, just push a button… This all reminds me, disturbingly, of the human characters in the film Wall-E. Corpulent, buoyed along on floating chairs, attended to by machines, sucking on drinks with straws, beholden to the “commodity form”. Here’s a clip in case you haven’t seen the film–

We’re not there yet, but you have to admit that we’re on our way. Most people’s lives (in the “rich” nations, anyway) are so devoid of physical labor that people work hard at their sedentary jobs and then spend the money they earn to pay to go exercise, and to do all the running and lifting that their grandparents would have done just to subsist. Worse, all of this comes at an environmental cost—resource consumption to create, market, and run our labor-saving devices, and then yet more resource consumption to create, market, and operate the machines in the gym.

So, my thought-of-the-day— embrace some of the physical work in your life. Or, as Gandhi put it, “One must learn to enjoy one’s chores”. If there’s a good side to our modern labor-saving devices, it’s that they give us the luxury of doing some picking and choosing when it comes to labor. We don’t have to slave in the mines, we can choose some slightly more fulfilling versions of exertion. My personal choices would be cooking with family and friends (with prep and clean-up, quite a bit of labor, but of the good sort), cutting and splitting firewood (time in the woods, alone or with someone else, fresh air, sunshine…), and gardening. Other people’s choices might be different, BUT— realize that no choice at all will put one on the path to floating-chair-land…

Video: PassivelySedentary, YouTube.

Project Photos, Phase One

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The meter sockets. The one on the right is the “gross meter” to record solar input to the grid. So far my wiring has passed muster with only a few minor changes needed. A small change required here; the equipment ground in the solar meter can’t go straight to the ground rod.

Well, I think I’m roughly on track with the add-a-bunch-more-solar project (if you missed it, see post from the other week “And the Project Begins“). I gave myself a month to complete the conduit runs underground, and we finished that today; almost two-thirds of a mile of conduit. Green Mountain Power is still waiting on one easement from a neighbor (a pole on their property will need an additional stay), so they can’t pull the high voltage wire in yet. But, my part is done, so it’s on to the solar panels on the barn roof. Some photos of this portion–

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The conduit at the house end of the run from the barn to the house. The main breaker is at the barn, so this is secondary power coming in to a 100-amp subpanel. The conduit on the right is for internet, with 500-lb strength pull cord getting pulled through as it gets put together.

 

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All the dogs, having a good romp.

 

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The main trench to the road; 42-inches deep. The high-voltage line will get pulled through this conduit; 7,000 volts in a single large co-axial cable, to a transformer at the barn. For this portion of the run we put the communications/internet conduit one foot above this one as we backfilled.

 

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The goal– to get to this stake. A single pole goes here, near the road, before the run goes underground. The last few feet can’t be dug until the pole is set, and then it has to be backfilled immediately and tamped.

 

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The deep well for the transformer (cabinet visible behind the dirt pile), and the internet conduits stubbed up in the foreground. The internet run splits from the power run at both cabinets; communications cables must be at least five feet from the high-voltage cabinets.

 

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The view down the valley as we work. It’s been reasonably pleasant so far, but I’m definitely racing winter; a bit of snow the other evening was a reminder…

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The new 225-amp load center in the barn, with the solar feed coming in at the top, the grid power coming in from the left, and the feed to the house going out toward the bottom (not all of the cables are attached in this photo).

Anyway, last night I unpacked all the invertors and racking and other parts for the solar modules on the roof, and I’ll just call that part “Phase Two”. I’ve given myself a month to get that part in place; I’ll post pictures.