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Green Homes

A True Net-Zero Gut Rehab, New England-Style

Teaming up with a topnotch builder and respected energy consultant, homeowner Jane Bindley achieved net-zero performance with her fully renovated SIP-wrapped home.
Image Credit: Ben Southworth
View Gallery 14 images
Nothing special. Before retrofit work began, this 1978 ranch house on the shore of Squam Lake was an ordinary fiberglass-insulated energy hog.
Image Credit: Ben Southworth
The view is to the north. Since most of its windows face north — the direction of the lake views — the Squam Lake house breaks a basic rule of passive solar design. The photo shows the north-facing sliding-glass doors before retrofit work began.
Image Credit: Ben Southworth
After the roof overhangs at the eaves and rakes were lopped off (following the “chainsaw retrofit” technique), the seams between the panels of plywood roof and wall sheathing were sealed with peel-and-stick tape.
Image Credit: Ben Southworth
After the exterior roof and walls of the house were encased in a new shell of 6 1/2-inch-thick structural insulated panels (SIPs), the rafter cavities and stud bays were filled with closed-cell spray polyurethane foam.
Image Credit: Ben Southworth
This photo shows the pergola, the sitting porch added on to the existing home (minus the attached garage where the south-facing sliders are).
Image Credit: Ben Southworth
To retain her view of Squam Lake, Jane Bindley decided to retain extensive north-facing glazing. The doors' triple glazing prevents comfort complaints.
Image Credit: Heather Burkham
Although space heating is usually provided by a ground-source heat pump, the house also has a wood stove.
Image Credit: Fletcher Manley
The completed kitchen includes a concrete countertop.
Image Credit: Fletcher Manley
The new front entrance also features triple-pane high performance glazing.
Image Credit: Fletcher Manley
Interior walls were finished with American Clay plaster.
Image Credit: Fletcher Manley
The wall SIPs sit on a steel L-bracket. The SIPs were attached to the existing studs with 9-in. screws.
Image Credit: Ben Southworth
Jane Bindley has accumulated an electricity credit with her local utility, so her electric bill shows that in each of the last 12 months, her electricity usage is zero kilowatt-hours.
Image Credit: Jane Bindley
The Bindley lot plan of existing land and structures.
Image Credit: Jane Bindley
Bindley's masterminds - That's Marc Rosebaum - EnergySmiths on the left and Ben Southworth - Garland Mill on the right.
Image Credit: Jane Bindley

Even huge north-facing sliders could not overwhelm the most meticulous air sealing and insulating details, moving a leaky ’70s ranch to cutting-edge energy performance

By Peter Yost and Martin Holladay

Before retrofit work began, Jane Bindley’s 1978 ranch house on the shore of Squam Lake was an ordinary fiberglass-insulated energy hog. Bindley had a dream: to turn her home in central New Hampshire into a net-zero-energy house. How hard could that be?

As it turned out, pretty hard. But with help from a dedicated team of experts and a generous budget, Bindley achieved her dream.

Can a north-facing house be net-zero?

Bindley chose her team wisely. She hired a New Hampshire company, Garland Mill Timberframes, to renovate her home. Ben Southworth from Garland Mill is an experienced design/build contractor. When it came time to choose an energy consultant, Southworth advised Bindley to select Marc Rosenbaum, one of the most experienced designers of net-zero-energy homes in the country.

Southworth doubted that Bindley’s nondescript ranch was worth saving. “I told her, ‘It will cost more money to take it apart than to bulldoze it,’” said Southworth. “But she answered, ‘It’s structurally sound, and I can’t imagine putting the house in a landfill.’ ”

The house sits on the shore of Squam Lake, with a spectacular view of the lake to the north. Most of the home’s windows face the view. “We were killed from a solar perspective,” said Southworth. “The house is up against a big hill on the south side, and the hill has tall trees. We put as many PV panels as we could on the south roof. Since we were aiming for net-zero energy, the PV array defined what our heat load had to be.” The house ended up with a 7.5-kW PV system.

Rosenbaum rose to the challenge. “The house has an incredible building envelope, which was an attempt to compensate for the drawbacks of the site and the north-facing windows,” said Rosenbaum. “The south roof gets a lot of winter shading. There was a low-slope roof with a 5/12 pitch, and we couldn’t raise the roof or the solar array because of zoning restrictions. So we needed a kick-ass envelope. The envelope specs came from doing the math.”

Creating a very tight, well insulated envelope

The home’s vinyl siding and roof shingles were stripped and the interior of the house was gutted. Most of the materials removed from the house were recycled or reused.

Adopting the “chainsaw retrofit” approach, Southworth and Rosenbaum decided to cut off the home’s roof overhangs. Once the seams between the existing sheathing panels were sealed with peel-and-stick tape, the roof and all of the exterior walls were covered with new 6 1/2-inch-thick structural insulated panels (SIPs). The urethane-insulated SIPs are rated at R-35.

Wrapping the home with SIPs was unusual; many builders would have simply wrapped the house with 6 inches of rigid foam. But Southworth is an experienced timber-framer who prefers to use techniques with which he is familiar — and he’s used SIPs for years.

Once the SIPs were attached to the framing and sealed at the seams with spray foam, the house already had a pretty decent thermal envelope. But Southworth and Rosenbaum weren’t done. The next step was to fill the 2×6 stud walls with closed-cell spray polyurethane foam, bringing the R-value of the walls up to R-52. The rafters were sprayed with foam until the roof totaled R-73, while the basement walls were sprayed to achieve R-42. The basement floor was insulated with R-25 of rigid foam.

All of the existing windows were replaced with triple-glazed fiberglass windows from Thermotech. Although Rosenbaum tried to talk Bindley into reducing the area of north-facing glass, she didn’t want to give up her dramatic lake view — so most of the home’s glazing still faces north.


Taping the exterior sheathing and spraying the interior with polyurethane foam created a very tight building envelope. Rosenbaum used a theatrical fog machine to track down a few stubborn leakage paths. A pre-retrofit blower door test put the home’s air leakage rate at 4,000 cfm at 50 Pascals. After retrofit work was complete, a second blower-door test showed that the house was now Passivhaus-tight, with a leakage rate of only 330 cfm at 50 Pascals.

Details on those sliding door insulating panels

“But I bet 50% of that 330 cfm is the north-facing sliding glass doors,” said Ben Southworth. “We went through several designs of insulating, air-tight panels for the sliders. Marc really wanted to put the insulating slider panels on the outside, but that was just not practical for Jane.” They ended up with 1.5-inch-thick 4′ by 8′ rigid polyisocyanurate panels with felt weatherstripping at the perimeter. The panels fit snugly into place in the deep interior pockets of the new door openings.

“I have an easy place down the hall to store the panels and they are easy to move into place,” says owner Jane Bindley. Jane has had no problems with condensation even though the panels are not completely airtight and are sometimes left in place for extended periods of time.

The finishing touch on the slider insulating panels is likely to be…art. Southworth’s lead carpenter wrapped the panels with white housewrap with the idea that a close friend of Jane’s, an artist, will someday turn the insulating panels into a view of their own.

What about the attached garage?

“It was a huge design win!” exclaimed Southworth. “First, moving the garage gave us much easier continuity on the building envelope. But it also eliminated a major source of IAQ concerns in a house this tight.

“Second, the garage was taking up the best south- and west-facing usable outdoor space on the property — space we turned into the organic garden Jane had been dreaming of. Third, we were able to hide the new garage in the bank of an otherwise unusable hill, and its green roof helps to reduce run off from busy Route 3 to the lake.

“And finally, instead of the focal point of the front of the home being double garage doors (that completely hid the front entrance), you approach the home now and are drawn to the garden and front entry and don’t see the garage at all. Making Jane’s home zero energy was essential to everyone on this project, but making it beautiful is arguably just as important.”

What kind of heat pump is most cost-effective?

The house has two heat sources: a wood stove and a water-to-water ground-source heat pump. The in-floor hydronic distribution system uses 95°F water circulating through PEX tubing. Since the water temperature is significantly lower than the temperature for some radiant floors — especially staple-up systems, which sometimes require 130°F or 140°F water — the heat pump’s efficiency is much higher than it would be if it needed to raise the water to a higher temperature.

Ductless minisplit air-source heat pumps are much less expensive than ground-source heat pumps (GSHPs). Although a ductless minisplit requires a little more electricity to operate than a GSHP, a net-zero-energy house can provide the necessary electricity by specifying a somewhat larger PV array than would be needed for a GSHP. The cost of the extra PV modules is generally much less than the incremental cost of a GSHP compared to a ductless minisplit unit.

When asked why he specified a GSHP rather than a ductless minisplit, Rosenbaum identified two main reasons:

  • The limited area available for the PV array favored a heating system that used as little electricity as possible.
  • Japanese ductless minisplits rated for below-zero outdoor temperatures were not available in the U.S. when the Bindley project was under construction.

“Japanese minisplit units are getting better all the time, and they cost much less than a ground-source heat pump,” said Rosenbaum. “I predict that the ground-source heat pump industry will be eviscerated by the Japanese minisplits.”

Since domestic hot water needs to be at a higher temperature than the water circulating through the radiant floor, the domestic hot water system is entirely separate from the space heating system. The two roof-mounted solar thermal collectors are connected to two hot water storage tanks; backup heat is provided by an electric resistance element.

True net-zero performance

Utility bills confirm that in 2009, Bindley’s renovated house produced 1,732 kWh more electricity than it used. The extra electricity more than balanced the small amount of firewood (0.2 cord) that Bindley burned. That means that the Bindley house is one of only a handful of U.S. homes able to document 12 months of net-zero-energy performance.

Several factors contributed to the home’s performance, including:

  • The home’s exceptional thermal envelope.
  • The fact that Bindley covers her windows with movable R-7 foam-filled insulation panels at night.
  • The fact that the home is only occupied for about half the year.

Although Bindley sends more energy to the grid than she consumes, she still pays electric bills of $21.41 a month; that’s the minimum fee collected by the local utility, regardless of usage.

Getting to net-zero isn’t cheap

Now that the U.S. Department of Energy is informing builders to prepare for a transition to zero-energy design and construction standards, it’s worth contemplating the steepness of the road ahead. Bindley’s house is an exciting example of elegant engineering, but it cost an arm and a leg. Her insulation package cost $110,000; her PV array cost $60,000; her windows cost $37,000; her Warmboard subflooring cost $20,000. The wells for the heat pump along with thermally enhanced grout and the thermo-coupling of the supply and return lines from the wells to the house all cost $30,000. The Waterfurnace unit was $4500. The Vaughn 80 gallon hot water tank for storage of the heating water was about $1000. Finally, the solar thermal system cost about $10,000.

“Depending on how you crunch the numbers, the house cost between $350 and $400 a square foot,” said Southworth. In other words, Bindley’s deep-energy retrofit cost at least $1,190,000.

“The material choices were expensive,” Southworth explained. “Every decision we made was the most expensive option.” According to Rosenbaum, “The energy package could have been done for less money if we had used less spray foam.”

A dream job

For energy nerds, the Bindley job is likely to represent the very archetype, the exemplar, the Platonic ideal of the perfect energy-retrofit job. Jane Bindley didn’t want to build a mansion; she just wanted to turn her 1978 ranch into a zero-energy home, and she had the budget to make it happen.

“Jane Bindley is an amazing person,” said Rosenbaum. “She would show up with coolers full of food and drinks for the workers — with more food than even the construction guys could eat.”

Southworth also remembers the job-site meals. “She would come every Thursday and make lunch for us, using ingredients from Whole Foods,” said Southworth. “She was wonderful.” Southworth also noted that Bindley, a physical therapist, “was always dragging guys off and giving them a massage.”

Talk of the town

Jane Bindley has done more home tours than she cares to clearly remember, but she firmly believes that her home should be an example. “And now, twice a day during the season, the Squam Lake tour boat slows in front of my home as the tour guide points out a true net-zero energy home,” says Jane with well-deserved pride.

Bindley loves her new home. “I once lived in a 1970s house that was very drafty,” said Bindley. “This house is a pure delight in the wintertime, because it is invitingly warm and the air quality is so good. The air is moist and there are no drafts.”

NOTE: For another great tour of this project, go to Garland Mill Timberframes.

Lessons Learned

One striking lesson from the Bindley job: if you’re aiming to build a net-zero-energy home in a cold climate, your envelope is going to end up looking like a Passivhaus envelope. Although some writers have contrasted the Passivhaus design approach with the net-zero-energy approach, in fact the two design approaches show signs of convergent evolution.

To get to the stringent net-zero-energy goal, you need Passivhaus levels of airtightness and Passivhaus levels of insulation — at least if you expect to fit all of the necessary PV modules on your roof.

Another lesson: if you’re aiming for net-zero energy, renovation may cost more than new construction.

Finally, Ben wanted to make sure that we understood how important Jane's grace was on this project. "It's a wonderful thing when you work for and with a person with as much presence as Jane Bindley. Green building is about integration, making the whole much greater than its parts. You can extend that definition to people; Jane knows how important people are to the whole process and made everyone of us on the job feel valued and part of the whole."

General Specs and Team

Location: Holderness, NH
Bedrooms: 3
Bathrooms: 3.5
Living Space: 3400
Cost: 375
Additional Notes: Living space area includes finished basement Energy Details Heating degree days: 7,500 Heat loss at design temperature: 23,400 BTU/h Annual heat load: 8,500 kWh Annual domestic hot water budget: 2,660 kWh

Design/build services: Garland Mill Timberframes Energy consultant: Marc Rosenbaum, Energysmiths


- LED lighting
- Ground-source heat pump

Energy Specs

- Basement floor R-value: R-25
- Basement wall R-value: R-40
- Wall R-value: R-52
- Roof R-value: R-73
- Blower door test results: 330 cfm50 (shell area 6,243 square feet)
- Windows: Triple-glazed double low-e Thermotech windows with fiberglass frames
- Window area: 568 square feet
- Space heating system: Water Furnace ground-source heat pump with three 220-ft. deep vertical closed ground loops; heat distributed through in-floor hydronic tubing (95°F water); supplemented by a woodstove.
- Domestic hot water: 2 solar thermal collectors connected to 200 gallons of storage; electric resistance backup.

Water Efficiency

- Toto Auqia dual flush toilets
- Hot water on-demand recirculation system
- .5 gom faucet aerators
- 1.5 gpm showerheads

Indoor Air Quality

- Mechanical ventilation: Renewaire ERV
- AFM Safecoat low-VOC finishes

Green Materials and Resource Efficiency

- New roofing: standing-seam steel
- Interior finish: American Clay plaster
- 90% construction waste recycling
- local stone used throughout all landscaping
- all interior doors from salvaged stock
- Forest Stewardship Council Certified (FSC) cedar siding
- FSC hemlock timberframe
- FSC birch kitchen and built-in
- FSC maple closets and built-ins
- FSC pine trim
- FSC wide board antique pine/oak flooring
- Local eastern white pine flooring and siding
- FSC garape deck for porch floors
- FSC heart of pine stairs
- Salvage maple handrails
- FSC SPF framing lumber and interior partitions
- Green roof with low-bush blueberries (Rooflite engineered growing media)

Alternate Energy Utilization

PV array: 7.5-kW array (Sunpower PV modules)
Annual PV production: 6,800 kWh


  1. Drew Jones | | #1

    Is it worth it? In this case, no.
    As an avid GBA reader and a full-blooded New Hampshirite, I am weary this is a vacation home. I hope I'm wrong, but if I'm right, you really can't claim net zero. Also, at what point do we draw the line on what's green? We all like to get paid, but obviously not removing at least some of an entire wall of north-facing sliding glass doors (despite what the customer wanted) helped achieve this $1.2 mil (low energy) retrofit. Special window inserts- what a joke!

  2. David | | #2

    This article really begs the question of what the definition of a true net-zero energy house is. Do we need to distinguish between "designed for net zero energy" use and "actual net zero energy use"? From my own personal experience I have found that not only does the house need to be designed for net zero energy use, but you also need a net zero energy family to live in it. I certainly do not doubt that Jane Bindley's home has the capability to be a net zero energy home, especially since Marc designed it. But if you are compelled to hang a label on it, looking at utility bills for a 3400 sf vacation home with one part time occupant and then labeling it a true verified net zero home does not seem quite right. It is barely occupied. You even say in your article that one of the factors that contributed to the home’s performance is.... "the fact that the home is only occupied for about half the year". That really puzzles me. If that is design advise then we should all be living outside half the year. I thought we were designing net zero homes for people to live in. So.... what IS right, if we even care? Don't we really need to define what a valid baseline occupancy should be, to use the label " A true net zero home". I would be curious to see a years worth of energy use data on that house after a full time family of four with 2 teenagers were living in it.

  3. MikeonaBike | | #3

    What I would do w $1.2 Million ?
    As an engineer this project is a great read, this would have been a dream job. However as someone who lives in a northeast city and see so many homes every day that are lacking windows, insulation, air sealing..... I dream of what if this owner had spent $12K on 100 homes, think of how much more energy/carbon could have been saved. Yes the finished product is a beautiful and extremely energy efficient home, but in the end it is something only 0.1% of can afford. To really make a difference in this world we need to focus on affordable low cost strategies. I think articles like this make "green" buildings even less attractive to the regular person as is suggests this technology is only available to the super wealthy.

  4. itserich | | #4

    the absurdity
    A fine demonstration of the absurdity Net Zero as a goal. Any home can be net zero with enough solar installed, anywhere. How is that impressive?

    Even ignoring that much of the energy created is wasted - created when it is not necessary. Because south facing panels create much less energy during peak periods than panels facing west.

  5. Expert Member
    Dana Dorsett | | #5

    What makes you think the peaks will always be PM? @ Erich
    NH is a heating dominated state with only modest air conditioning loads, but also limited natural gas grid. As more houses use heat pumps for space heating its highly likely that within the lifecycle of those PV panels the absolute annual peaks will be from space heating, not the typical CA PM peak, even if low-load days still have a PM peak.

    Before the lifecycle of those panels is up battery technology will be cheap enough to be cost effective time-shifting south facing PV to any hour of the day when the power is needed at New England type power rates. (No ,wait, it already is, but the regulatory environment hasn't caught up to re-make the wholesale markets to properly remunerate it, even on the larger scale, let alone aggregated at residential scale.)

    It's time to stop looking at it as if what's true this week, (or 6 years ago when that house was done) about diurnal load profiles and how the grid is operated. It's evolving much more quickly than most people realize. If you're seeing turning the panels west as the "right" thing, you're looking in the rear view mirror.

    Yes, even your house or mine could become Net Zero with enough PV panel, and it'll be financially rational to do so soon enough. Net Zero just a number, and not the most important number. But re-orienting panels to better align with the historical peaks of yesteryear is probably going to look pretty silly six years from now too, as the ISO-NE demand response market takes off, battery prices continue along their traditional learning curve, and electric vehicles start charging en masse. With enough EV and other battery load being managed, and with ubiquitous demand response resource, peak grid loads will occur whenever the grid operator needs/wants them to.

  6. itserich | | #6

    time to stop calling today an artifact
    Dana, in prior comments you referred to the absurd costs and failure to produce peak energy by rooftop solar as an "artifact."

    An artifact is an item of historical interest. You used the term incorrectly, because, of course, the same problems exist today, and will exist for several years, at least.

    It is certainly true, the huge problems with home based solar - the lack of both cost and resource efficiency - may someday be resolved.

    You and Martin are so smart, but he also made the glib comment that the costs of home and utility based solar are close and changing monthly, which based on the cost figures you cited are wildly untrue. Home based solar is 5-6+ times as expensive as utility.

    So yes, in the future things will change. But is not a minor historical aberration.

    As to installing solar, it will never make sense for many highly efficient homes. I retrofitted my house and though in a cold state, my peak heating cost, using a heat pump, is $100 per month. My utility provider expects to have 100% wind energy.

    I can't comprehend why it would make sense to install solar on my roof. This is the reality for homeowners who focus on extreme energy efficiency over "net zero."

    A battery, as I suggested as an alternative to home solar, is a whole different subject. Paint them bright fluorescent and mount them on a roof, and it might become popular.

  7. GBA Editor
    Martin Holladay | | #7

    Response to Erich Riesenberg
    Q. "I can't comprehend why it would make sense to install solar on my roof."

    A. Well, the main reason why my friends are installing PV arrays on their roof is because the financial returns on their investment are so good -- better than any stock, bond, or mutual fund. Some of these returns are due to the federal tax credit, of course, which (a) won't last forever, and (b) you probably disdain. But most taxpayers take advantage of all kinds of tax credits, including the mortgage interest deduction, without feeling that any painful moral compromise has occurred.

    Of course, if your locality doesn't offer net metering, you probably don't want to own a PV system. But if you live somewhere with net metering, your failure to comprehend why it makes sense to install solar on your roof is costing you money.

  8. itserich | | #8

    response to Martin
    Hi Martin - Sorry for your confusion. I was discussing my situation, and why it doesn't make sense to install solar on my insulated houses. The key word is MY

    And yes, it does extend to other highly efficient homes with utility providers who already acquire most of the electricity from renewable sources.

    I understand you are confused. My criticism is of the framework which encourages so much money and resources to be spent so inefficiently. Which is why I wrote: "A fine demonstration of the absurdity Net Zero as a goal."

    Do you also support fracking, because it produces cheap natural gas? Is cost the best metric?

  9. GBA Editor
    Martin Holladay | | #9

    Response to Erich Riesenberg
    So if I understand you correctly, you are declining a lower utility bill, even if the finances are favorable, because the low price of PV power is comparable to the low price of fracked gas -- and you feel you'd be morally tainted if you joined the PV bandwagon.

    It's a perfectly understandable ethical position, of course. But I think that the comparison to fracked gas is flawed. From my ethical perspective, I see no ethical problem to increased PV installations, and I would be happy (if I lived in a grid-connected house) to see lower electricity bills resulting from an investment in PV.

  10. itserich | | #10

    clarification for Martin
    Dear Martin - My utility bill is too small to make solar worthwhile. I am surprised you are so confused by it.

    Sure I might get some subsidies now, but assuming net metering will remain and the grid will remain free is glib folly. While I certainly do give more thought to moral values than most people, I also have a healthy dose of financial common sense. Look around, the world is in sorry shape because people can't manage their finances.

    I see you are also confused about my comment regarding cost. You state that installing inefficient, wasteful home based solar is logical, because it is profitable, to the homeowner. I disagree. Like so many wasteful, inefficient industries, including fossil fuels, the gains of home based solar accrue to the homeowner, while others pay the cost.

  11. Expert Member
    Dana Dorsett | | #11

    Artifact, schmartifact...
    "An artifact is an item of historical interest. You used the term incorrectly, because, of course, the same problems exist today, and will exist for several years, at least."

    Gotta call BS on these two.

    1: Artifact has several definitions and usages- you're cherry picking. Language is a social contract- words mean what users of those terms mean and understand them to mean.

    2: The evening peak "problem" and ramp rate from mid-day lull to the PM peak absolutely DOES NOT EXIST in New England today, and would not occur for several years even at the most optimistic projections of PV implemention within the ISO-New England grid region where that house is located.

    Currently on the ISO-New England grid region the absolute annual grid peaks (the ones that REALLY count, the ones that define the grid's capacity requirments) are the summertime air conditioning peaks, occurring between 2-4 PM on hot sunny days when south facing PV is still putting out more than 85% of their peak power for the day. Being that it's currently half-past February, today's predicted hourly load profile looks pretty ducky, with the anticipated peak of ~15.75 GW occurring between 5:30-6:30 PM. On hot summer days it looks more like the Matterhorn, with the peak occurring in the early to mid afternoon, peaking at about 24-25 GW (well above the PM peaks in the winter & shoulder season). Feel free to check back then:

    More quasi-real time data from the grid operator:

    Currently the mid-day lulls in load during non air conditioning seasons are still 4-5 GW above the overnight low-loads of 9-11 GW. Mid-day power produced by south facing PV still has a very REAL demand EVERY day, and would even at 10x the current amount of installed PV on the ISO-NE grid.

    The whole duck-curve evening peaks on low AC load days that would benefit from west facing arrays are a "nice to have" thing for the grid operators since it reduces the ramp rate requirements of dispatchable power to meet that load, but right now, today in New England there's really zero benefit- there is plenty of dispatchable resource to cover that (even despatchable stored hydro power), and the ramp rates are modest. The ramp rates are just beginning to be an issue in California today, at significantly higher insolation and several times the installed base of PV in New England relative to the total grid load. Currently as well as going forward, it's unlikely that there will EVER be a duck curve ramp rate problem in New England, for several reasons:

    By the time sufficient PV gets installed in New England that it would be an issue in this region, several other things will be pretty much oblitherating that potential problem- there will be bigger amounts of variable output power to manage, as well as the necessary storage capacity to manage it. Massachusetts has committed to building out the offshore wind to at least 1.6GW by 2027, and both the transmission line & storage capacity resources to manage it, starting with 200MWh by 2020, with more in the development pipeline, scheduling dependent upon how rapidly other variable output resources and storage resources (under state mandated & other, on both sides of the meter) get built. The NYISO next door (which trades power flows with ISO-NE at a very significant rate) is under similar sorts of state mandated development. There are also transmission line projects between Quebec & New Brunswick hydro resources under serious discussion that will likely be built before 2030, which can also ease any ramp. (A transmission line project that was ready for signatures just got quashed by NH regulators, but that's just another bump in the road for the regional grid development.)

    The demand response market within the ISO-NE won't be launched until 1 June of this year. Demand response can do a HUGE amount of load profile shaping to manage duck curve issues, at a lower cost than passing up some of the PV energy by turning arrays west. In the PJM region where demand response markets are already developed, even widedly distributed controlled loads are being aggregated and bid into the ancillary services and capacity markets, keeping the grid stable under high ramp rate conditions and low.

    Fixing a non-problem New England with something that would be a "nice to have" to ease potential problems in California's situation today is silly. Unlike California, the mandated storage for managing variable output power flows is occurring ahead of, or at worst concurrent with the major build out of non-dispatchable variable output generation.

  12. itserich | | #12

    Dana's BS
    Dana can you explain how you define the word artifact?

    I don't recall anyone ever discussing peak power periods in New England. Considering the rate of home based solar installation in New England versus California, probably not relevant. Am I wrong?

    Perhaps your point is, home based solar which is not installed, is not a problem?

  13. GBA Editor
    Martin Holladay | | #13

    Response to Erich Riesenberg
    A word search of this page reveals that it was you, Erich -- not Dana -- who was the first to use the word "artifact."

    Among the definitions for "artifact" from an online dictionary is "a product of artificial character (as in a scientific test) due usually to extraneous (such as human) agency."

  14. itserich | | #14

    origin of the word artifact
    Martin, the use of the word artifact goes back to last week's discussion, where Dana proclaimed ". This has been dubbed the "duck curve" in California, "Nessie curve" in Hawaii, but it's known artifact of a high PV grid (distributed or utility scale), and why a 100% PV grid isn't likely to be the most cost effective solution."

    That was the same discussion where Martin proclaimed: "Clearly the economics are complicated -- and changing monthly. Your skepticism is already or will soon be obsolete, however. While the installation costs for a homeowner-owned PV system are higher than the installation costs for a large utility-owned system, the benefits to the utility of distributed PV (as pointed out by Dana Dorsett in Comment #7) are significant, and may well justify the higher installation costs."

    Dana also stated in that same discussion home based solar cost is around 25 cents while utility based solar is around 5. Hard to comprehend how you conclude the economics are complicated. With that sort of cost disparity.

    The goal post keeps being moved, and this conversation continues to ignore the most basic facts.

  15. GBA Editor
    Martin Holladay | | #15

    Response to Erich Riesenberg
    If you have a comment on a thread posted elsewhere on GBA, you should post the comment on the same page as the discussion you are trying to join. Otherwise, we all get confused.

    I haven't moved any goal posts. On this page, I am trying to respond to comments posted on this page. I can't be expected to respond here to a thread on a different page. Your perception that the goal posts appear to have changed may be related to the fact that on this page, I'm only responding to the words I can see.

    I still don't know where the other comments are (where Dana used the word "artifact"). The comments you quote and attribute to me sound logical and defensible, though.

  16. Expert Member
    Dana Dorsett | | #16

    "Dana can you explain how you define the word artifact?"



    1: any object made by human work; esp., a simple or primitive tool, weapon, vessel, etc.

    2: any nonnatural feature or structure accidentally introduced into something being observed or studied


    Try #2.

    Regarding the cost of residential PV vs. utility, in the US the difference is HEAVILY dominated by soft costs, an artifact not found in German or Australian markets.

    That cost difference can, and inevitably will be reduced as the PV markets here develop to the level of competition in those markets. It's not as if German & Australian workers are any cheaper & smarter than in the US.

    Erich writes in response #14:

    "I don't recall anyone ever discussing peak power periods in New England."

    Seems someone named Erich wrote in response #4"

    "Even ignoring that much of the energy created is wasted - created when it is not necessary. Because south facing panels create much less energy during peak periods than panels facing west."

    I'm not sure how to parse "...south facing panels create much less energy during peak periods than panels facing west..." to mean anything other than this much criticized PV installation in NH (which is still in New England, under the ISO-NE grid control) isn't applying the power during peak demand periods.

    Erich continues in #14:

    "Considering the rate of home based solar installation in New England versus California, probably not relevant. Am I wrong?"

    Well, yes, "wrong" would be about right.

    Over the course of last April PV produced nearly 14% of all grid power in CA, in May it was over 17%. In New England it's less than 2% annually, less than 0.7% on the utility's side of the meter, visible in real time by the grid operator. (Need references?) Orders of magnitude matter. No state in New England has been nowhere near as aggressive in promoting, subsidizing, mandating or installing PV (on ether side of the meter) as CA, and it shows. By 2020 in MA alone there will be sufficient battery to manage any regional duck curve problems in the ISO-NE grid, and MA isn't the only New England state working on grid storage issues, just the first, and the state representing the biggest share of the ISO-NE load. Califonia's duck curve problem is something akin to the canary in the coal mine for states and grid regions playing catch-up on PV deployment. California is having to deploy the storage piece after the fact, but others have the luxury of learning by example, and synchronizing the deployment of storage with the deployment of non-dispatchable generation. These aren't "maybe, some day" developments in Massachusetts, this stuff has been legislated, mandated, & funded, with fairly firm deployment schedules on the first tranche, with enough flexibility in the remainder to move the schedules up or pull them back based on how the private markets and pricing develops, to take every advantage of the rapid learning curves of the technologies, as well as reacting properly to the scale of non-mandate private energy investment (large and small.)

    [edited to add]

    More on the MA storage mandate here:

    More on the ISO-NE grid development needs summarized here:

    Note- there is already nearly 3GW of demand response committed in the first round beginning in June. That's more than 10% of the annual peak grid load, and about 20% of the total non-cooling season total PM peak loads, and more than half the current load delta between the non-cooling season mid-day lull and the late afternoon/early evening peak. That's more than enough resource to manage the current level of ISO-NE duck-ramping with just demand response, no storage.

  17. Expert Member
    MALCOLM TAYLOR | | #17

    Net Metering Agreements
    I may be wrong but I think Erich's point about installing PV not being worthwhile on houses like his with low energy usage comes from the assumption that net metering agreements simply allow you to offset your consumption from the grid. While there are utilities that draw the line there, many others (like ours) will pay users for their excess production. I assume that's why Martin's neighbours are installing PV, no matter how low their utility bills are.

  18. GBA Editor
    Martin Holladay | | #18

    Response to Malcolm Taylor
    A PV system can make financial sense, even if a house has relatively low electricity bills, and even if the net-metering agreement resets the credit for surplus electricity production to zero every 12 months, without any carryover of PV credits beyond 12 months.

    In Comment #6, Erich told us that he heats with electricity -- it sounds as if he has an all-electric house. He told us that his heat pump uses $100 of electricity or less each month. How much electricity does he use annually? I don't know -- perhaps $800, perhaps $1,000, perhaps more. If he pays $0.10 per kWh for $1,000 of electricity, that would be 10,000 kWh per year. If he pays $0.20 per kWh for $1,000 of electricity, that would be 5,000 kWh per year.

    Depending on where Erich lives, he might need a PV system rated at between 3kW and 10 kW. This in fact is the typical range for a net-zero house. It's a big range, and I don't know where Erich is on that range -- I don't know his geographical location or annual energy use. But his system wouldn't be unusually small. The financial return depends on his net metering opportunities. There's no reason to reject the suggestion to install PV because of a mistaken idea that his PV system would be too small to make sense.

    For a financial analysis of two PV systems in Massachusetts -- one on Paul Eldrenkamp's house, and one on my brother's house -- see this article: Making Room for a PV Array. Of course, any financial analysis depends on many factors, including the local cost of electricity, the details of the local utility's net metering agreement, local tax breaks and subsidies, and the climate.

  19. Expert Member
    Dana Dorsett | | #19

    This just in... (for grid nerds only, with a nod to PV)
    Yesterday the Federal Energy Regulatory Commission issued a unanimous order that grid operators create special market tariffs for grid storage, stipulating that if a minimum size is required for market participation the minimum can be set no greater than 100kw (that's power, not energy storage capacity), which means even fairly small battery arrays or battery system aggregators will be able to stack the various type of value those systems are capable of delivering, and be remunerated for it, not just the energy storage value.

    In addition, all new generation resources, including renewables (but excluding heat & power cogenerators and nuclear plants) must provide frequency response services to the grid. While fast-ramping peakers, wind farms, inverters on solar arrays, and demand response aggregation can provide those services without batteries, slower ramping power can do that more cheaply with some amount of battery.

    This value stacking approach to compensating storage assets is going to super-charge the markets for building this stuff, independently of how much local PV is co-located on those grids. With the storage assets in place, of COURSE they would be using them for time-shifting PV (and nuclear and gas plant) output to align better with market demand, since that's one of the other values on the stack, if not THE driving value for installing them. This is revolutionary, and the "Point the panels west, young man" theory of optimizing PV value is going to fade into the sunset faster than anybody ever thought, given the mandated new value streams that storage will be allowed to monetize.

    As with demand response markets it will take a couple of years before those markets to take off, but the grid operators have 270 days (today is day 1) to implement the market rules for storage.

    More details:

  20. itserich | | #20

    clarification for Dana
    Hi Dana. I am sorry for your confusion. Perhaps you should slow down and read before posting.

    My comment about solar not producing during peak power was based on a New York Times article, based on a California study which showed how little home based solar panels produce during peak periods.

    Not At All Complicated. Not a human construct. Not historical. Not an artifact.

  21. itserich | | #21

    flashback for Martin
    Hi Martin. GBA did not allow me to post to last week's discussion. Drupal is a great website infrastructure, I am sure GBA will get it figured out one of these decades.

    My comment in that thread, and again at the start of this thread, was to compare home based solar with utility based solar. The real cost of home based solar, in my state, sounds like it is several dollars per kilowatt. Compared with the cost of wind energy, which my utility is moving towards 100% electrical generation.

    My only comment was that utility based renewable energy is less costly and produces more energy per resources spent. Everything Dana has said seems to support that. It seems obvious.

    My goal is to reduce my energy use, period.

    I am not interested in discussing subsidies, how to make a few thousand dollars over 20 years. It sounds silly to me.

  22. itserich | | #22

    my energy use
    Oh, and my energy use is about 500 kwh per year for cooling, maybe 3,000 kwh for heating. And that is without a real heat pump. This is just testing things out for me. I use a portable heat pump most of the winter and electrical resistance during the coldest period. I am sure it would be less with a real heat pump, but no hurry. Same reason not to mess with solar panels, what a hassle when my utility does it so much better.

  23. Jon_R | | #23

    > market participation the
    > market participation the minimum can be set no greater than 100kw

    100kw @ 250V = 400A. Not practical for the typical electric car at home (unless aggregation is allowed).

  24. Expert Member
    Dana Dorsett | | #24

    Probably kicking a dead horse...
    Recent discussions on PV & Net Zero prompted revisiting this thread, but ISO-NE is now looking hard at (and planning for) the impending "Duck Curve", that has been an urgent topic in California & Hawaii:

    At only 1% of the total power going onto the ISO-NE grid it's still years from becoming a management problem. The amount of wind power going onto the grid here is still an order of magnitude larger, and still demands more attention than PV. We're now only a handful of weeks away from the launch of a demand-response market which will help manage and time shift load to match variable output generation such as wind & PV.

    Meanwhile back at the dead horse, comment in #22 (which I only read today) was pretty rich:

    "My comment about solar not producing during peak power was based on a New York Times article, based on a California study which showed how little home based solar panels produce during peak periods."

    Which is exactly to the point: The California study is not relevant here- this is New Hampshire. The timing of daily peaks is not universal- peaks in California are not much related to peaks in NH. CA has large evening peaks from residential air conditioning to manage, peaking around 7PM. NH/New England does not. Of the homes in NH that have AC more than half (about 60%) are using window units with much smaller draw than central air. In CA it's about 75% central-air with a much bigger draw. The absolute annual grid load peaks in both regions are still summertime mid-day from commercial AC, when mid-day PV output is most welcome (and valuable).

    The actual comment (in #4) was:

    "Even ignoring that much of the energy created is wasted - created when it is not necessary. Because south facing panels create much less energy during peak periods than panels facing west."

    Still patently false for this region, and demonstrably so.

    In NH (and all of ISO-NE the annual absolute peaks are still in mid-day during the mid to late summer, when PV output is also quite high. The only time the evening peak is a problem for PV (in either NH or CA) is during the shoulder seasons when the daily peak is much lower, but not occuring during mid-day when PV output could potentially, eventually outstrip mid-day demand, creating a very steep ramp as the PV fades ahead of the evening peak. This "duck curve", which still not a problem in NH, and the tools for managing it are being put in place well ahead of it reaching that point, since they're the same tools for managing the variable output of the regional wind, as well as the absolute annual peaks.

    The mid-day power output is still (in 2018) quite valuable, far from "...when it is not necessary...", and during the shoulder season the power delivered during the morning & evening peaks of the still pretty-flat (compared to CA) ISO-NE duck curve still isn't particularly more valuable than the mid-day power. That mid-day power is still needed, still valuable here.

    The more pronounced duck curve won't starting in the early to mid 2020s , the 6GW+ red bands in the shoulder season and winter season graphics:

    Even the belly of the duck at 8 GW of PV is still well above the daily load minimum in winter, and over half the daily load minimums during the shoulder seasons. New England isn't likely to hit the 8GW mark for PV until mid 2023 (and only if the recently applied PV tariffs get reversed.)

    Right now, May 2018 we're in the yellow bands, still under 3GW, PV and definitely not a problem. The demand curves on any day of the year mid-day output is quite valuable, hardly a case where "...much of the energy created is wasted..." .

    By 2025 everything will be different- the load curves will have a deeper belly to the duck but will also have the demand-response market and storage market corrections. Unlike CA it will not have an uncontrolled low duck belly with an extreme ramp neck to a high evening peak duck head. (There will also be at least another GW of variable output offshore wind added to the mix by then.) But the demand response market will be fairly mature by 2025, lopping some off both the tail & head of the duck while sucking up the belly, and the mandated (by MA) amount of storage will be reducing the value of gas-fired peaker power for belly-to-head ramp management.

    By 2030, who knows? By then the PV on that house will be nearing end of life, and both the storage & demand response markets will have evolved to produce very different demand curves than the dumb-grid model curves that CAISO and ISO-NE have been wrestling with. Maybe it would make sense to mount any replacements or additions on the west side, but that's not a slam-dunk- at the decade-plus distance there's too much murk in the crystal ball.

    But the 5 year crystal ball is pretty clear: South facing PV is still more valuable to the grid operator and ratepayers than west facing in this region. Turning the panels west would only raise the 8-10AM tail of the duck while pushing the 6-8 PM portion of the neck ramp down, and will do NOTHING for the 8-9AM shoulder season peak seen in the ISO-NE curve for late April. (The sun is already down prior to the daily peaks in April.)

    Jon_R: For the record, aggregation is expressly allowed for bidding into in storage markets, and the 100kw is a MAXIMUM allowed minimum if the market operators want to set a minimum. There is no requirement to actually set a minimum, just a limit to how low any set minimum would be allowed.

  25. Expert Member
    Dana Dorsett | | #25

    This just in: Yesterday ISO-NE reported a first, where behind the meter PV pushed the mid-afternoon load lower than the overnight load on 21 April 2018:

    The demand peak on that still occurred at about 9 PM, which is 1.5 hours after sunset. Turning the panels west would not reduce the peak, nor would it improve the ramp-rate significantly (but would increase the AM peak.)

    Unlike how things historically rolled out in California over the past 10-15 years, ISO-NE has been planning for the onslaught of variable output renewables well in advance of they're being built, and have the benefit of learning from California's experience. Subsidizing turning PV panels west is not currently in their integration plans for managing it.

    More here:

    Note, in this last link hey are projecting that the 6 GW solar line won't be crossed until the late 2020s ("...over 5,800 MW are expected by 2027.."), but note that over 8GW (8000MW ) of wind proposals are already on the books (of which at least 3GW will be built)). The capacity factors of onshore wind in New England is roughly twice that of PV, and the projected capacity factors for offshore wind will be about 4x that of PV. With more installed nameplate capacity than PV at a 2x or better capacity factor it's clear than managing the WIND is still going to be a bigger deal for the grid operator than managing the PV. While the seasonal average output of wind is predictable months/years in advance, the hour & day of hitting the nameplate capacity is much less predictable than with PV, which will always be zero after sunset and before sunrise, and has a predictable theoretical maximum and for any day and hour of the year. Winds blow hard at any hour of the day, and can be much calmer at any hour of the day. The type & size of the tools needed to manage the wind variability as the projected amount wind capacity gets built will also tame the PV duck (without turning panels west.)

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