A reader using the name “Joe” left a comment on Wednesday’s post (“Energy economics and changing politics reshaping the solar industry“) which is worth responding to because it appears to reflect a misunderstanding of the debate over net metering.
Joe wrote:
I don’t buy the electric utilities’ grid capacity argument against net metering.
If the wires to my house can deliver 100 amps, they can return 100 amps. If the wires to the block can deliver 2000 amps, they can return 2000 amps.
An average 6KW solar system could produce a peak of 25 amps at 240 volts. Normal output levels would be somewhat lower, and some part of that will probably be consumed by electrical devices in the house.
So how is it that my 100 amp line is not capable of handing 25 amps?
The basic misconception here is that the problem with net metering has something to do with the carrying capacity of the wires to your house. Not so.
In what has become the traditional rooftop solar system, electricity is produced during sunny, daylight hours and fed into the utility’s grid. The utility pays for all the power that is fed into the system. At the end of the month, or the billing period, the amount paid for the purchase of that power by the utility is deducted from the amount the homeowner is billed for the power they draw from the grid during the same period. The amount they end up owing to the utility is the difference between those amounts.
There are several important points, in my view. That is that the homeowner with a rooftop solar system doesn’t use the power produced on their roof. It all goes into the grid. So if there’s a disruption in the grid–a traffic accident knocks over a utility pole and disrupts power, or a storm blows through and does broader damage to the utility lines–your rooftop system doesn’t power your house. It’s still trying to feed the power produced into the grid, even if the grid is not available.
Second, without expensive modifications to the existing electrical grid, there’s no way for the utility to regulate the amount of power they accept from each rooftop system.
To quote Morita again, “the output from rooftop solar is a must take resource.”
She explains:
Therefore, when there is excess electricity being generated due to low demand, it is the lower cost utility scale renewable generators, or electric utility generators and independent power producers that provide baseload and regulation power to stabilize the system that are being curtailed with a possible outcome of putting the entire electric grid at risk or making the utility run less efficiently and at higher costs. But, yet, these generators and other utility resources must still be available to ramp up rapidly to meet evening peak demand.
The old net metering incentives included paying top retail prices for rooftop solar output, even if that meant dumping cheaper, utility scale power that would otherwise be available. It was good for the homeowner being paid for their solar power, but not so good for the rest of consumers who had to pay the resulting higher rates.
Third, that is highly relevant because rooftop solar, and other types of solar installations, produce electricity during the day, but in Hawaii, the period of peak usage of electricity is at night. So at some point, and that point has long since been reached in Hawaii, rooftop solar is producing more than the system needs during the day, without any economical way to store or shift that power into the evening, when the overall demand is the greatest.
The point of all this is that it’s a complicated set of technical and economic issues that have to get sorted out. And while these are being confronted by utilities across the country, Hawaii is running into the wall first because of the success of the solar industry here.
Again, I highly recommend Mina Morita’s blog, Energy Dynamics, for insights into the situation we are all caught up in.
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It would help if more of the rooftop PV panels faced west, so their generation peak would be later in the day (relative to the more common south-facing panels) and continue later into the day, thus more closely matching demand.
Net metering created an incentive to maximize energy conversion from light to electricity, and no incentive for any matching of generation to consumption. The PUC’s changes create that incentive, so I would think we’d start seeing more west-facing PV panels.
The changes to the net metering program also provide an incentive to shift consumption to more closely match generation. E.g., if you have an electric water heater, put it on a timer to only run during mid-day.
“without expensive modifications to the existing electrical grid, there’s no way for the utility to regulate the amount of power they accept from each rooftop system. ”
Not quite. At least in theory, they could regulate it by forcing the rooftop system owners to provide that regulation.
Ideally, such an owner-provided regulation system would shunt excess power to a storage system that could be tapped during peak demand.
For any HECO PV projects, they have a very strong incentive to match generation to demand, so I would think most of those project would have most of their panels facing west.
I wonder if this is actually the case?
Thanks for the analysis.
There is a limit to how much electricity a rooftop solar system can return to the grid. If the house has 100-amp electric service, then the solar system could not send more than 100 amps into the grid, because it would trip the circuit breaker. I understand that this limit may be trivial in the aggregate context.
Electricity is much cheaper here ($0.08/kWh, primarily hydroelectric) so we have fewer rooftop solar installations. I believe net metering is allowed here.
Now I’m curious – are electrical generation plants in Hawaii actually not producing electricity during peak solar output periods? That seems like a worthwhile goal.
Proposals for more west facing solar panels to better match electrical load on the surface sound good but as a practical matter would not make much difference.
First, many houses do not have a west facing roof or not enough to take the full compliment of solar panels. You can tip the south facing panels more west but that would involve raising them above the roof thus exposing them to increased wind load, an unacceptable tradeoff. Second, this time of year, the sun sets so far south that west facing panels are only marginally more productive than south facing panels. Further, for those of us living in a valley or on the windward side, the sun drops behind the mountains well before sunset so west facing panels don’t provide much advantage. Bottom line is that peak electrical demand is around 7:00pm but residential solar does not produce significant power beyond about 4:00pm. So, no amount of fiddling with panel orientation is going to do much to match HECo’s load profile.
One final thought. Why should I tailor my solar installation to accommodate HECo’s load profile. The panels are paid for with my nickel to provide power for my needs including maximizing my net metering return. HECo. needs to manage the grid as they always have. Yes, the demand profile is changing so they have to adjust to that.
There’s also the energy justice angle. Given the costs associated and installation issues, most of the PV capacity has been taken by people who least need a break in their electrical bills. The same people who are now loudly complaining about the need for increased grid capacity. Guess who largely bears the brunt of that? Renters, apartment dwellers, condo owners, anyone who doesn’t own their roof or couldn’t afford to install PV during the gold rush. There’s some interesting demographic and economic characteristics for the people who will bear the majority of the cost for more grid capacity.
As for rFerdun’s question, “Why should I tailor my solar installation to accommodate HECo’s load profile[?]”
Answer: Because you benefit from the grid and if you want to free yourself of the burdens that it imposes, then you must disconnect from the grid and generate all your own power. Hope you’ve got enough cash lying around to buy a new car, because that’s what it’s going to cost you to rewire your house and buy all the batteries, plus the expertise to install them. Don’t underestimate or undervalue what society has provided for you.l
Here is an article that displays the notorious ‘duck curve’.
http://www.greentechmedia.com/articles/read/the-grid-has-changed-how-energy-efficiency-can-help-manage-the-duck
Just a few years ago (2012), the afternoon was a time of increased electricity production for utilities. But with the penetration of solar power onto the grid, the utilities have scaled back their electricity production during the day. The problem with this is that in the evenings from 4 p.m. to 7 p.m., as the sun sets and solar energy power wanes and people come home from work, the utilities have to ramp up their centralized electricity production. Their infrastructure for doing so, however, was not designed for this kind of dramatically accelerated production of electricity.
The article argues that ‘energy efficiency’ needs to be re-conceptualized to include ways of shifting energy production from evening to daylight hours, and not just refer to using less electricity (e.g., LED bulbs and fuel efficient vehicles). The example of air-conditioning is given, with thermal-storage systems drawing from the grid during the day and cooling buildings off-grid during the evening.
But what else can we do to shift electricity production to daylight hours and away from evening?
One idea might be all-in-one washer-dryer combos. People would put their clothes into the machine in the evening or the morning, set the timer for the afternoon, and come home to clean laundry.
http://washer-dryer-combo-review.toptenreviews.com/
LG makes the highest rated machine for $2,000. Is that affordable for most people? It would preclude the purchase of two machines that would probably cost that much together anyway. (It would also save space.)
In the aftermath of the oil shortages of the 1970s, it was widely assumed that the US needed to invest in new coal and nuclear power plants to keep up with rising demand. Critics argued that renewable energy could not only supply the growing need for energy, but replace existing fossil fuel use.
Both groups turned out to be wrong. Demand for energy in the US plateaued as Americans practiced conservation. Later, natural gas began to replace fossil fuels.
So conservation might be an overlooked strategy as the world turns toward renewable energy.
One of the standards for constructing buildings that conserve energy is LEED.
https://en.wikipedia.org/wiki/Leadership_in_Energy_and_Environmental_Design
Buildings are evaluated across six credit categories and awarded a maximum of 100 possible base points, resulting in four levels of certification.
1. Certified: 40–49 points
2. Silver: 50–59 points
3. Gold: 60–79 points
4. Platinum: 80 points and above
On the one hand, pursuing a LEED rating raises the cost of construction. On the other hand, even small investments pay dividends in the long term, with “an initial up-front investment of 2% extra yield[ing] over ten times that initial investment over the life cycle of the building.”
Another such rating system for energy efficiency is EnergyStar. https://en.wikipedia.org/wiki/Energy_Star
Looking at these two standards (LEED, EnergyStar) and the experience of their implementation, can we conclude that it would be realistic to build new structures in the state to be 20% more energy efficient than current standards? Would it be possible to gradually retrofit older structures into this standard? More specifically, what exactly are the current standards? Do current structures actually conform to those standards?
Rephrasing the above questions into economic terms, Could this be done affordably? What would be the financing mechanism for those who could not easily pay for these upgrades? (Loans? Tax breaks?) Are such mechanisms even necessary?
How should the construction of buildings be modified to promote energy efficiency? One form of sustainable architecture emphasizes the use natural materials. Such buildings are made of adobe, cob, cordwood, earthbag, rammed earth, stucco, stone, straw bale, and timber frame.
https://en.wikipedia.org/wiki/Natural_building
First, these are not conventional buildings, and one would assume would have a limited market. (In work spaces, people tend to desire a building that has the latest cutting-edge technology, but in domestic architecture people tend to be traditionalists and want something charmingly old-fashioned, even corny, like some Victorian-styled homes. In contrast, ‘natural buildings’ are neither.)
Second, this kind of sustainability is aimed at having a low carbon footprint, as opposed to reducing energy consumption; the object is to prevent global warming, as opposed to preparing against post-peak oil shortages.
With ‘natural buildings’, there is a big emphasis on using wood, especially sustainably harvested lumber. Such timber actually REMOVES carbon from the atmosphere.
The University of British Columbia plans to build an 18-story residence tower for its students completely out of wood. (The article also mentions the proposed 35-story wooden building for Paris.)
http://www.huffingtonpost.ca/2015/10/05/ubc-wood-residence_n_8247582.html
Here is a nine-story apartment complex in London constructed entirely of timber. The panels used are assembled in a factory, and are so thick that they are essentially fire-resistant by themselves. They are also easy to assemble.
http://www.bdcnetwork.com/worlds-tallest-all-wood-residential-structure-opens-london
Would it be possible to grow forests locally for sustainable lumber? (My impression is that eucalyptus is the most economically viable large-scale source of timber in the tropics, but it is highly flammable and not good for wood work, and is consequently used primarily for paper production and for stove pellets. It also crowds out natural forests, and does not sustain other plant and animal life. So it’s not really a eucalyptus ‘forest’, it’s a eucalyptus tree farm.)
At the forefront of energy conservation is the ‘passive house’ design pioneered in northern Europe.
https://en.wikipedia.org/wiki/Passive_house
Passive-house design seems to be developed around using the environment to warm a building with minimal human input.
However, there are examples of using these principles to cool buildings, as well.
https://en.wikipedia.org/wiki/Passive_house#Tropical_climate_needs
Heat pumps would transfer heat from rooms into hot water heaters. (I’ve never even heard of that.)
Interestingly, in warm countries like Mexico, kitchens in the nicer houses are often built on top floors, and bedrooms are on the bottom floors. Also, ceilings are higher to dissipate heat. (It’s interesting that the architecture in places like Florida, the southwestern US, southern California and Hawaii is based on designs from cooler regions.)
It turns out that there is an article on ‘passive cooling’ that I missed. It’s all about designing a house that cools itself without the need for energy inputs.
https://en.wikipedia.org/wiki/Passive_cooling
Techniques to do this include cross ventilation and ‘stack ventilation’, which is basically the chimney effect, in which warm air in the interior rises to a vent near the ceiling, and cooler fresh air is brought in from the ground level.
One can find all of these features in the graceful, subtle architecture of Vladimir Ossipoff. (Ossipoff was the chief architect of Honolulu Int’l Airport, which utilizes these techniques brilliantly and beautifully).
https://en.wikipedia.org/wiki/Vladimir_Ossipoff
(Interestingly, in the social and economic context, this kind of architecture has a parallel with PV solar systems. These things are great for society, without a doubt. Everyone benefits when anyone owns these things. We need more of these things. But the people who benefit the most from them are those who own it. Those people tend to be affluent. The rest of us live in generic houses and pay higher energy bills.)
“A low-energy house is any type of house that from design, technologies and building products uses less energy, from any source, than a traditional or average contemporary house.”
https://en.wikipedia.org/wiki/Low-energy_house
More specifically, “in Europe it generally refers to a house that uses around half of the German or Swiss low-energy standards referred to below for space heating”. First, those German and Swiss standards are probably already quite rigorous, and it is striking that going even further in energy savings is a major goal. Second, the focus is typically on heating homes in cold climates; there is little mention of low-energy use in warm climates.
There is something like this in the US, with California calling for a 40% reduction in home energy consumption by 2020. “Deep-energy retrofits” would make this possible.
http://aceee.org/blog/2014/03/50-energy-savings-residential-sector-
Deep-energy retrofits sound excellent – for those who can afford it. Perhaps more modest goals would be in line for the rest of us.
Should homes be required to meet certain goals of energy efficiency based on the value of the home, with higher-end homes being subject to more stringent efficiency standards? Would this not save those homeowners money in the long run, and improve the value of their homes?
There is an article on ‘deep energy retrofits’ that I missed. “A deep energy retrofit is a whole-building analysis and construction process that uses “integrative design” to achieve much larger energy savings than conventional energy retrofits.”
https://en.wikipedia.org/wiki/Deep_energy_retrofit
The Empire State Building in NYC got a deep energy retrofit a few years ago.
http://www.greenbiz.com/blog/2013/06/29/empire-state-building-retrofit-new-projects
A $550 million retrofit? The following site says that the Empire State Building has 2.7 million square feet of space, and the retrofit cost $204 per square foot. That is $550 million. (Also, the retrofit raised the Empire State Building’s EnergyStar rating from 52% to 90%.) The innovation here is in the financing. Also, the real objective was to attract new tenants to the building, which always suffered from under-capacity (the “Empty State Building”). That worked, and new tenants have moved in, drawn by the cachet of working in a green building.
http://www.rmi.org/retrofit_depot_get_connected_true_retrofit_stories##empire
Zero-energy buildings need to be defined carefully.
https://en.wikipedia.org/wiki/Zero-energy_building
Notice that the emphasis is on the (otherwise hidden) word ‘net’.
This means that such homes still draw from the grid, but also contribute to it in equal parts. Nowadays, in places like southern California and Hawaii, it’s a lot of houses that do just that – they give as much as they take from the grid.
So, in a remarkably short period of time, the nature of zero-energy buildings (ZEB) has changed radically. Just a few years ago, to become a ZEB, buildings would have to be radically retrofitted or built from scratch to be energy efficient in order to have reduced electricity demands. But with solar PV prices falling at 17% a year (according to the article), that is no longer necessary. Increasing solar PV supply and not reduced household demand now characterize ZEB.
The article fails to mention, however, that the number of houses that can feed the grid is somewhat limited, that the grid can become saturated, at least without storage. This might make it imperative that the houses without solar PV be retrofitted to be more energy efficient (although conceivably, this would reduce demand for electricity even more, and further limit the grid market).
(Interestingly, there are no examples in the article of ZEB structures in Hawaii, which is on the forefront of renewable energy in the US.)
The federal Investment Tax Credit is being extended. This is good news for battery storage, because historically when it has been installed with solar PV, it has qualified for tax credits.
http://www.greentechmedia.com/articles/read/what-the-federal-itc-extension-means-for-the-us-energy-storage-market
I’ve been wondering why battery storage does not qualify for Net Energy Metering (NEM) at the local level. Increasing levels of solar PV disrupt the grid, but battery storage moderates that. So while there may be good and necessary reasons to roll back subsidies of solar PV, but this is not the case for storage. (In fact, more storage means more solar PV can be installed.) Also, because the number of homes that can have solar PV is therefore limited, subsidies for solar PV disproportionate benefited the affluent; the rest of us have now been locked out with the end of NEM. That is not true with battery storage. (Also, I imagine that even homes without solar PV could have battery storage, drawing from the grid in the day, and feeding the home and the grid in the evening. This would help to flatten the ‘duck curve’.)
There has been a lot of bold talk about how people are going to buy batteries and get off the grid. But that is not necessarily what is happening or is going to happen. Utilities are not necessarily obsolete if they leave behind the monopoly mindframe and embrace dynamism and customer service.
http://www.greentechmedia.com/articles/read/grid-defection-isnt-a-reason-to-fight-distributed-energy