Should personal solar generating capacity really matter
What are folks’ thoughts on how well we’re considering futures in our infrastructure build-out strategies?
As per the title, one example is when we allow proclamation of ‘net-zero’ by way of installing offsetting solar generation capacity. Problem is—demand and generation won’t match, and while we can perhaps add enough battery storage to allow matching, is that the most economical from a systems wide approach?
When we say the cost of adding solar is cheaper than that extra inch of insulation (for example) is that properly considering the costs of future demand management with a changing grid and resource mix? (And don’t forget transportation additions).
I understand that there’s too many unknowns to answer this in precise terms—but I’m nonetheless curious of folks’ thoughts on how good a job we’re doing with current construction decisions with an eye towards future systems wide planning. Such topics that come to mind are: embodied carbon analyses, personal generation capacity, insulation levels, development scale / land-use planning.
How do we integrate these (and other) concepts in a systems wide analysis. Perhaps that’s too tall an order and counter productive to simply making progress (perfect being the enemy of good type of thing perhaps?)
In simpler terms, should we be placing higher value on certain things, (like insulation or thermal storage vs rooftop solar for example, or location and density of housing vs insulation, etc?)
I think lots of people here are thinking these things through.
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The answer to the actual value will vary (a lot) by location within the distribution grids, the congestion of of the local grid, the future cost of distributed grid storage (on either side of the meter), the cost of grid upgrades to relieve congestion issues, etc. New York planners have made at least some attempt to figure this out, but it's a moving target with lots of moving parts (and prices). The consensus a few years ago was that distributed PV + storage in targeted areas would be cheaper than upgrading the Brooklyn-Queens substation, but getting firefighters to go along with their increased hazards & training was just one obstacles (among several) adding calendar time and cost to that solution. I haven't tracked it very closely lately, but there is a lot of information about it online.
But it's not just about energy or the delivered cost/Mwh. Super Storm Sandy generated a lot of interest in the enhanced value of distributed resources and micro-grids, and that hasn't abated much. It's hard to put a firm price tag on the value of having at least some local power while a storm-shredded distribution grid is being repaired. Even if the levelized cost of $/Mwh is higher with a distributed resources solution, it can still be "worth it", when the social costs and economic costs of being out of power for hours/days/weeks on end are factored in.
A islandable fossil-free nano-grid at the single-house scale with an average reliability on par with the typical US utility is probably never going to make economic sense. But distributed resources still have real value. Vermont's Green Mountain Power has a pretty good hybrid solution of distributed batteries in homes that are at least partially under utility control for grid balancing purposes, that also serve as carbon-free backup for many hours for the homeowners. Whether it's worth it to the homeowner depends a bit on how reliable their local grid is, and how critical it is to have continuous power even when the grid is dropping out during a storm:
https://greenmountainpower.com/product/powerwall/
Vermont's distribution grids are pretty far flung & rural, making them a bit more susceptible to storm damage than some other areas, but the concept works everywhere.
>"but getting firefighters to go along with their increased hazards & training was just one obstacles (among several) adding calendar time and cost to that solution. "
yes I'm sure non-technical issues (or peripheral to the technical) are a huge chunk of costs and decision making criteria.
“Should personal solar generating capacity really matter”
Matter to whom?
If you want to be grid connected then it matters to the utility. My local utility will not connect a system likely to generate more than 80% of your predicted usage. It somehow you end up generating more than you use they credit your account at about 10% of the retail billing rate making generating excess electricity to sell to my utility a very poor investment.
Large scale electrical storage does not work in terms of dollars and cents with current technology.
One of the nice things about this country is you are free to spend your money as you please. If you decide you want to spend so many dollars on insulation that the insulation you could never recover the money in fuel savings, feel free it is your money.
If you decide you want to make choices based on a different set of values that’s fine by me just don’t try to force others to make poor economic choices so you can feel better.
Walta
Yeah my phrasing was a bit odd.
I was primarily trying to drive at the point that there is value in considering both social costs (as opposed to just individual) and future costs (as opposed to just capital or simpler ROI analysis).
I'm not viewing it as limiting personal freedoms or controlling anyone's spending, per se, but about making informed decisions at an effective scale.
My thinking with the solar is guesswork (based on what I've heard) about managing the potentially high costs of peak loads on a future grid heavily laden by VRE's and (possibly) supporting the demand of transportation and heating. It's likely too far away to effectively add future costs into current equations, but just found it to be an interesting thought experiment.
A key part of the idea involves not just making the decision, but implementing ways (market solutions? policy?) to allow the decisions to make financial sense NOW for the sake of the near future (and social costs). Some future costs will remain vague and unobtainable, yet certainly some will be more predictable and worth basing decisions on.
I don’t like the concept of “embodied carbon” and have never used it. Carbon is not equivalent with energy.
In terms of rooftop solar, I think of it as a way to offset electrical demand, but not a contributor to the grid itself as a resource. In the industry, this is known as “peak shave”. The peak output of solar lines up pretty well with peak grid load hours, so solar helps to reduce peak loads, and peak loads are often handled by the least efficiency generation on the grid (which is only run at times of peak load).
Solar has its place. I don’t like small scale residential battery storage. Batteries are a wear item with a finite lifetime, and they aren’t very good for energy density or the cost to store that energy. You’re better off with a grid connected system. You’re still offsetting the same amount of energy during the day and using grid power at night. There is a much lower installed cost this way, and you end up with a more flexible system.
I don’t see micro grids as being worth the headaches of synchronization. A nice idea, but not worth the complexity, in my opinion. I should point out that in spread out areas like Vermont, those really long lines are transmission lines (BIG lines), which tend to be MUCH more reliable than the distribution lines that usually take most of the damage from storms. That’s a good thing: it means that using distant energy sources aren’t as bad in terms of reduced reliability than you might think, although they do have some increased risk of disconnection from storms or system problems. There is no perfect option, unfortunately.
Bill
Yeah embodied carbon might be a lazy term. But terminology aside, I'm personally fine with taking into consideration the amount of CO2 equivalent released in the making/transportation/installation of goods. More than fine actually, I think it's quite valuable, for the very reason of 'future costs.'
>"this is known as “peak shave”. The peak output of solar lines up pretty well with peak grid load hours, so solar helps to reduce peak loads"
I'm premising all this on changing parameters, one of which (from my understanding) is that peak demand could likely move to the heating season in northern climates. Or at the least, not line up exactly with solar generation.
Another change being high penetration of VRE's, which makes the storage (in its many forms) somewhat essential. No longer will we be able to rely on 'the grid' as a sort of virtual storage like people currently do with rooftop solar (and that is essentially the point of my question). Rooftop solar seems to come with an eventual expanded price tag (who pays?) in the form of storage, transmission/distribution upgrades, smart techs, etc. Whereas a super insulated structure or something like thermal storage does it's load shaving in a relatively low tech, durable, and somewhat future proof way. This is of course a simplification and I'm really not at all against rooftop solar. I'm more just trying to hit at a larger cost balancing equation.
Certainly we can't and won't accurately predict and account for all relevant future costs, especially given the development rates of tech and other economic/societal trends. But I do think looking ahead to some of these scenarios may help inform us on building technology and planning strategies. Moving it to the real is a whole nother thing.
>”I'm premising all this on changing parameters, one of which (from my understanding) is that peak demand could likely move to the heating season in northern climates. Or at the least, not line up exactly with solar generation.”
That’s actually the case in the Pacific Northwest, and is the reason the pacific DC intertie was built — it allows excess northern production to go south in the summer when peak air conditioning load occurs in the south, but can be reversed in the winter if extra capacity is needed in the north for heating.
Right now, peak load is typically in the summer most everywhere. I suppose if there were to be a large transition to electrically operated heating units (heat pumps, primarily), peak load probably wouldn’t shift, but would end up being similar in both the winter and the summer.
Remember that any time energy changes form, some of it is lost. This is why small-scale battery storage isn’t particularly efficient. Larger systems can get better efficiencies by using higher battery string voltages, but there are still losses.
Bill
Bill,
for DC lines to allow two-way power trading (as with the pacific inter-tie you mention), do they need to be specifically designed for such (technically speaking, like a certain type of converter?)
I ask because the DC powerline project in Maine is going to be sending power from Canada to New England, but it seems like in the future, sending power back from NE to Canada could be beneficial. Do they have to plan for this now, during construction? (There's an MIT study that points out the benefit of allowing two way flows on this line. I'm hoping they're planning for that).
Yes, it needs to be allowed for in the design, but differently than you might think.
On the DC side, which includes BOTH converter stations, it’s mostly control logic that needs to allow for bidirectional power flow, along with some filters on the AC side of the converter. The line (wire) part is no different.
On the AC side, there are power flow issues that have to be looked at in the area of the converter stations on both ends. This basically means the existing AC grid in the immediate area of the converter stations on both ends needs to have sufficient capacity to allow for bidirectional power flow.
If you look at the pacific DC intertie, you’ll see that it has different capacities in each direction. This is due to design limits and system constraints.
ABB (the company) builds a lot of these systems and has some good info about them on their website if you’re curious. Another system is the highgate converter in Vermont.
Bill