@enipla what solar company are you using? How is the system treating you so far? Do you use Xcel, and what rate do they pay you for power?
I really wasn’t considering solar, mostly because of money and our old roof. We replaced the roof last December. I was talking to my mother-in-law about her solar, and didn’t mention anything about getting our own, but she said to talk to her before we make any commitments on solar, because she can give my wife and I each $20k tax free.
So now, all of the sudden, I’m thinking about solar. Due to interest rates, the weirdness of leases, and the gift offer, I’d probably pay cash. That at least keeps the calculations simple (I’m really not considering the opportunity cost in such an unpredictable market).
My city is part of this bulk-buy program, and their online only recommendation is a 6.97kW (17 panel) system for $19k, from Solar Wave. My other estimate, because I can get it without having to leave an email address or talk to anyone, is from Tesla, for $32,000, including a 13.5kWh battery. The bulk discount program prices a Tesla Powerwall at $14k, so a bit cheaper through Tesla.
I do not want to buy from Tesla.
I don’t think I want a battery either, but Xcel will pay me $350 per kWh for installing a battery. That knocks nearly $5000 off the price of a Powerwall (though I still don’t want to buy more Tesla). Even with the discount, I don’t think it is worth it, because I don’t care about the blackout feature of the battery.
The primary use of the battery will be to collect energy during the day, and then charge the car at night. However, it looks like Xcel’s solar credits means I can just use the entire grid as a virtual battery. I get credit for any power I feed into the grid when the sun shines, and then I can use that credit to charge the car at night. I think they deliberately try to make it very complicated though, so I may not be understanding it.
Thoughts? Opinons? Is $14k (after tax credits) for a 6.97kWh system good, bad?
At $2/W installed, it’s entirely reasonable (leaning towards “good”), especially if it’s a service that your city has already vetted (did they? are there public reviews/other homeowners’ experiences available, or people you can talk to about their firsthand experience?). I think finding a good company buy from is the hardest part of the equation; many are sketchy or outright scams. So if the group buy service already did their homework (and isn’t, hopefully, itself a scam), that peace of mind alone can be worth a lot… IMHO.
Can you get the actual documentation (contract, terms, etc.) of how this works? At first glance it sounds too good to be true — akin to the terms of 15-20 years ago, when solar was still relatively new and conditions were more favorable to homeowners. The way you describe it, it sounds like the grid is just one big battery of “1 kWh in, 1 kWh out, whenever you want, no strings attached”. That is almost never the way it works anymore, at least in populous states with a lot (too much) home solar. Time-of-use pricing and different input vs output credit values (you sell at a huge markdown, buy at a markup) combine to make it such that your solar generation is usually only worth a tiny, tiny percent of what you’d buy back from the grid, especially if (like most people) your system feeds into the grid during peak solar hours and buys it back at night. That’s the least advantageous for your utility. Most of them suffer from too much power during the day and don’t want to buy yours, certainly not at retail value, unless your state forces them through legislation. It really depends on what the terms say. Their website isn’t very straightforward about how it works: Xcel Energy
Absent clear & legally enforceable language to the contrary, I would probably default to assuming “there’s probably something you’re missing and the actual deal you’d get from them is much worse”.
On the other hand, if your home battery does support time-shifting, AND you are under a time-of-use rate (or will be forced to change to one after the solar install), that’s when using your own battery to do the time-shifting (instead of the grid) can be advantageous. But it also depends on whether you actually “own” the battery and can fully control it, or whether your group buy or utility NEM program gives them some “smart” control over your home battery (which may affect your rates differently).
There’s a lot of variables, highly dependent your local laws, utility rules, which rate plan you’re on, the equipment you get, etc. If you wanted to be sure, you’d have to look at the legal language of every single part of this to really understand how it works.
Or maybe ask the city if there’s some administrator or help desk for the group buy program that can help you navigate these intricacies? Without that group by, these are the sorts of questions that a (good) solar company should help you analyze, for your specific scenario. Sadly, the bad ones will take advantage of that same confusion and sell you outright lies. And it’s not easy to tell apart the good vs bad ones… I hate talking to salespeople too, but if I were buying home solar, I’d speak to at least 3-4 local installers, ask them to explain all of that, and use their answers (in terms of clarity, honesty, and correctness) to help gauge which one to buy from. If you don’t want to do that, then you’d have to read through all the jargon on your own (AI can maybe help parse it) and try to make sure understand how it all actually works…
And to make it all worse, all of those variables change tend to change every few years, usually for the worse. As more and more home solar gets installed, the grids have a harder and harder time dealing with it, and the NEM agreements get worse and worse. Hopefully whatever agreement you sign has a minimum term that you can do some reliable math against…
It’s often a shitty and confusing industry with multiplayer players working against each other, all of them against you. Your city might have some climate goals to meet, your utility is trying to maintain grid stability and its own profits, the solar manufacturers want to sell commodity hardware in a cutthroat market, and the installers are trying to navigate all of that in a difficult labor market while trying to make a profit for their (usually) small-biz owners. And none of them are really on your side, as the homeowner… you have everyone working against your needs, and you’re almost always the party with the least information to boot. It sucks =/
Find the actual language of your NEM agreement, read it (or post it, or ask AI about it), and double-check with whoever you can (another installer, family members, friends, lawyers, whatever) before you sign anything.
The panels are black! So says the offer. Digging deeper, the panels are from Solar Hyperion and the inverters are Enphase iQ8+ Microinverters. The panel warranty is
30 Year Performance
25 Year Product
25 Year Workmanship
5 Year Production Guarantee
and the inverters have a 25 year warranty for product, performance, labor, and workmanship.
Thank you, those are exactly the kind of questions which seem obvious to ask, once you’re told to ask them.
That is what is claimed of the whole point of the Switch Together program. They vette suppliers, and then take reverse bids to get a bulk rate for anyone who participates. I put my name into the pool in 2023, during the first round of bids, and they selected Sandbox Solar, “Colorado’s #1 solar installer.” They still exist, so that is a good sign.
I got confused (trademark suite time?). The current provider is Smart Wave Solar, not Solarwave, as I originally said. Smart Wave Solar has a website, that is about all I can say about them. They appear to be a Utah company that also services Colorado (nothing wrong with that).
I wish. This is what I have (pdf). I’m convinced it is deliberately confusing, because the website directs you to the PDF, and the PDF directs you to the website. Neither mentions numbers, but talks abou the AHIC rate and TOU rate.
The PDF says “The dollar value of a solar credit is based on the price of electricity at the time of day the electricity is generated,” but “based on” does a lot of work there. A ratio of 1:1 and 10:1 are both “based on”. So they certainly make it easy to interpret it as a straight 1:1 trade, but careful reading, I don’t see that it says that anywhere.
I’m under time of use, and 85-90% of my energy is in the lowest tier, because it’s charging the car at night. Last month being on TOU saved me $17 over the fixed rate. People always hate on TOU, but I’m one of the cases the utilities weren’t able to optimize around, so I save money.
Xcel is changing the TOU times so that 5-9pm is peak time, and the rest of the day is off peak. That makes total sense if they have lots of solar they need to deal with.
Thank you for your input. The bulk agreement stuff “answers” lots of questions, but they’re much more on the level of “how can I find my roof size” not “what are the exact details of the NEM agreement.”
That’s what we have. 1:1 credit for what we put back on to the grid. However, I love having the batteries for outages. And for going “off grid” when they say they’re experiencing peak demand.
ETA I hate Tesla as much as anyone, but their Powerwall and app are really cool and work great (so far at least)
Just to add to the above excellent cometary. Using a battery to charge a car is almost invariably the worst possible thing to do. Even with a significant subsidy on the purchase, the value of the energy saved over the lifetime of the battery will usually result in making a loss. Batteries come into their own when time shifting energy from cheap daytime solar to very expensive peak evening rates. Replacing overnight off peak rates into a car is just going to wear the battery out prematurely with nothing to show for it.
As noted above. The actual rates you get for generated energy versus what you pay are a moving target and pretty much always slanted against you. But overnight base load power isn’t going away anytime soon. So cheap overnight rates to charge a car are usually available and make time shifting energy from a battery a very bad deal.
Batteries that are subsidised by joining a virtual power grid are often a bad deal as well. A friend of mine has a Powerwall installed as part of one. The one time he really wanted the battery when the power went out, the virtual grid had already discharged it to about 20%. The power in the house failed long before mains power was restored. The value in money saved by time shifting is very lineball over the life of the battery. In a lot of ways subsidised battery schemes are more about getting you to subsidise batteries for the benefit of the grid.
Much depends on your local power production modes and market. Large scale interconnection of grids can make for unexpected wholesale prices and concomitant retail weirdness. It really pays to dig into this and not take what you are told by random salesdroids at face value.
Where I am, overnight base load power often comes halfway across the country from legacy coal burning plants. Locally the last coal burner was shut down some years ago. No nuclear here at all. Gas turbines are used for peak supply. The market can get quite volatile. But I can charge my car overnight for peanuts. That I am almost certain this is charging it from coal is unfortunate. But it is what it is.
During the summer, I can charge it on weekends from solar. I save a couple of cents per kilowatt hour. The big savings with solar is running the house aircon.
Yes, I realize this, which is why I’m leaning heavily against a battery. In October the peak usage moves to be only 5-9pm. I’ll just end up not using the AC at all during that time. Right now, where peak is 12-7pm, the thermostat moves up to 80F. Off peak it is at 70F, and the whole house is just a thermal battery. Even on 95+ days the AC might not kick on at all until 7pm.
From what I can tell, it is a 1:1 banking of power. Banked power can only be withdrawn during the same TOU that it was saved, which is completely fine for car charging and AC. I think the bank rolls over month to month, but is cashed out at the end of the year. I think the cash out price is lower than the normal electric rate. Maybe if I have a sunny year I’ll have to invite all my EV friends over to charger.
The exact details of this are the biggest question I have.
Years ago Xcel put on the bill the tons of CO2 you caused to be produced based on their generation mixture. I don’t know if they stopped because it was inaccurate, embarrassing for them, or if they just got bored. It did reveal that commuting alone to work (28 miles round trip) I produced the same amount of CO2 in the EV or on the motorcycle (65MPG).
ION solar. It’s not installed yet. Our power company is very slow to grant permits. Need one because we are going with net metering (you sort of sell excess power back to them). We where told that they are slow on this process. If for some reason we get denied I suppose we will go with battery.
We are on Xcel. I couldn’t tell you what the rate is. We are moving to the new house that will have solar and things are in a bit of disarray
I’m guessing here, but this is one potential scenario: In a given year, you can 1:1 offset up to 100% of your own usage (maybe with some time-of-use adjustments, not sure). If your panels produce more than 100% of your own usage, on an annual basis, then the utility buys the excess from you at a much lower rate. Or maybe some of it rolls over to the next year.
In any case, that’s just an example, but it’s a common enough scheme that lets the homeowner offset their own usage while not make a profit by selling to the grid. Really, all this means is to properly size your solar system — don’t get a huge, oversized array that produces way more than you’ll conceivably need, because the excess power probably won’t get you much.
In cases like that, you usually end up saving money over 7-10 years vs paying retail electricity — especially if the price of retail electricity continues to go up, which I would expect it to. On top of the solar equipment, you’d probably also end up paying the utility some monthly fees for distribution, etc., but a lot less than buying power from them directly.
If you’re concerned about any of this, you can probably call either Xcel and/or the installation company and ask for details, preferably in writing.
My guess is that if the solar equipment is indeed vetted by Switch Together, as you said, then you’ll probably come out ahead in a decade or so, maybe less if the sun is favorable. Although the utility NEM schemes aren’t as good as they were in the past, they’re still generally able to offset your own usage over the year, or else nobody would bother with solar.
Yeah, that. “Smart” batteries, meters, washer/dryers, HVAC, etc. are there for your utility’s sake, not yours. They allow the utility and/or state to time-shift individual household usages to better distribute the demand across different times of day.
This isn’t necessarily a bad thing, mind you (it’s kinda an important way to stabilize the grid as more and more renewables enter the mix), but the marketing around it is often evil… especially if you want a battery for backup purposes.
On the other hand, if they clearly label it as a VPP (virtual power plant) use case and sell it to you very cheaply, there is a possibility it can save you money over the years. Maybe, maybe not, depends on a lot of math. Basically what @Francis_Vaughan said
I wouldn’t get a home battery if I were you, especially not knowing the details about the Xcel NEM agreement.
If anything, maybe your next EV could back-power the house (like the Ford truck) and that way at least you have control over it, and it’s a battery you’re using every day anyway (for driving).
The ION guy (salesman I’m not kidding myself) said that we should be fine with electric cars in the future to charge, and an existing hot tub. He asked all the right questions. He even said that “If you go battery, it will increase my commission” Just suggesting it will cost a lot more.
I asked to add two more panels. Ya never know…
Our newish house has plug ins for electric vehicles. And we won’t have to drive nearly as much as we do in the mountains. Our new favorite restaurant is only 2 miles away.
They’re not very expensive, anyway, relative to the overall costs of installation. A few more panels is totally reasonable, just don’t oversize it by like 2-3x hoping to make a profit selling to the utility (not that you were).
It should be possible to double-check his math (it’s not terribly hard) if you want to make sure your system is sized appropriately for both your current and future needs.
I’m in the middle of selling my home and moving to a new one. I left my math and another bunch of stuff in a box somewhere.
My Wife and I gave up labeling the boxes because it’s turned into a jumbled mess. I don’t care. We need out in 4 days. 130 mile drive one way to new house. Our cars are packed.
And then we have to consider the two 65lb dogs that travel with us. A lot of conversations are “Well if you take one dog… My Wife is taking both tomorrow. The dogs are confused for sure, but they LOVE the new place.
This doesn’t address the specific deals offered to @echoreply, but I understand that cheap batteries are shifting the economics of solar in obvious and not-so-obvious ways. Over at Volts, David Roberts interviewed Kostantsa Rangelova of ember-energy.org
Yeah. So picture a solar panel, and it usually produces for just a few hours. When the sun is highest, it produces a peak. And then you have a few, like, shoulder hours where you still have some generation, but it’s not as high as the peak in the middle of the day, which means that the grid connection that you have should theoretically match that peak production that only happens for a few hours, but then for the rest of the time, you’re not using the grid connection. But if you build even more solar panels and flatten the curve in a way that you’re not producing just for a few hours, but you’re producing constant electricity with enough solar and then the battery capturing that excess and flattening it out.
This means that you can use the grid connection all the time. And instead of 20%, you can go all the way up to 100% utilization and also sell a lot more solar into the grid.
I never thought about the limits any particular grid connection, and how solar in the middle of the day could exceed those limits. I don’t know how relevant this is to the home generation scenario, or whether it mostly applies to utility-scale power systems. (I’m also not sure about whether I understand this properly.)
They’re talking about utility-scale solar + storage. It’s a bit different because:
Home-scale systems (typically just referred to as “battery backup” instead of “solar + storage” — difference in marketing terms) are subject to the utility’s time-of-use and solar credit rules (see the last few posts about a 1:1 payback or something else)
Utility-scale solar + storage systems are usually not subject to the same pricing rules, since it’s the utility itself installing them or buying them from a third-party industrial partner
But they are subject to other concerns, like land use (it’s not always easy to buy land or easements close enough to existing settlements or infrastructure) and national security (different batteries and minerals require supply chains that aren’t always easy to maintain, especially in the face of changing tariffs and national security concerns)
For home users or small pilot projects, batteries that are cheap today are good enough. But, like the interview says, the situation changes constantly, and what’s cheap or available today may not be tomorrow (from a national security or regional grid stability perspective). It’s not a great idea to bet your country’s energy future on foreign suppliers, who are often (or may soon become) your rivals…
China is going to kill it in terms of their access to raw battery materials, advanced automated factories, cheap labor, and relatively minimal environmental regulations. They also have lower per-capita electricity use (but a lot more people).
In the US, we are looking for new sources of battery materials, some domestic and some foreign but not Chinese. But our advanced battery engineering and especially manufacturing capacity is still in its infancy compared to Asia, and with the Republicans de-prioritizing this line of research and trying to stir a resurgence in fossil fuels, it’s not clear whether we’ll be able to catch up… we still do a lot of R&D, but we don’t really have the manufacturing scale to wholesale replace our current grids with solar + storage. It’s one thing to put up a few pilot projects here and there, and to know what theoretically works, but it’s another thing to replace all the ancient infrastructure (both electrical and economic/political) in 50 different states. Part of the challenge is technological/engineering (battery chemistries and sourcing), part of it is political will (much less now that the Dems aren’t in power), and part of it is the investment money & manpower (much of which is flowing to AI instead).
It’d be nice to see more of that, of course, but at our scale, it’s not a simple problem. Utilities here and there are adopting more and more of it, but it’s different in every locality & grid.
Thank you all for your comments and advice. I was holding off on replying until I had more news.
The biggest issue is the looming end of the 30% tax credit for solar installs. My interpretation of the December 31 deadline is the same as what the solar installers gave, but with the giant caveat, that until there are IRS guidelines, we don’t really know. We interpret the rules to mean that in order to qualify for the tax credit a system must be payed for and installed by December 31, but not necessarily producing power.
The non-profits[1] my city is working with on group installs hosted a meeting with the three companies they are using for installs in my area. I was matched with the largest of them, who is also the only one still scheduling installs for 2025, Smart Wave Solar. They think they can still get an install done before the end of 2025, if we proceed soon. I did not interpret this as a high pressure tactic, just reality.
These are the steps
Site survey
Engineering design
Design acceptance
Permitting from the city and Xcel Energy
Installation
It is the permitting from Xcel that is the largest delay. It can’t be started until the design is accepted, and construction can’t start without the permit. Xcel is under pressure from the state government to issue permits as quickly as possible, but the installers still expect it to take 45 days.
My estimates are that solar is a good investment for me. A $20k system should cover 100% of my electrical needs, so $13k after the tax credit. Comparing saving $13k at 4% interest for 25 years versus spending it on solar now, the solar should be a net positive of about $12k. That is assuming electrical rates stay steady, which they are not. Supposedly Xcel is allowed to raise rates 4% per year, and they intend to.
Talking with the installers, and as discussed here, a battery doesn’t make much sense for my needs. Their advice is to wait for new battery technology, and reevaluate every few years. Changes in net meetering may also change the battery value equation.
So now I’m just waiting to schedule the site survey.
Same here. But it got approved, and I just found out a new meter was installed. I didn’t have any outage as far as I can tell. I did look at the meter, It looks new and different.
Yeah. Ours will be about 30k. But there was a LOT to consider. My Wife and I are retiring soon. So we will, no doubt be using more elec. We are gonna end up with electric cars as well I’m sure. This should cover all of that.
The proceeds from our previous house will buy the new house and the solar system. It was a no brainer. As we will be retired, it will be nice to flatten electric costs out a little bit for budget. Not that I’ve every really made a budget in my life, it was usually, uh ohhh… that was my budget.
But we are doing good for the environment. That’s huge. We have a gas fireplace on the first level. I suspect we will retire to the basement more in the winter. Bought a dart board for down there. As cheesy as they are, the electric fireplaces are getting better. I will get one for down there.
I used to live at 11,200 feet in the Rocky mountains. I heated solely with wood for about 6 years. Was rough.
I gave my chainsaw away, because… No, I’m done with that. In fact, I don’t have any gas engine tools at all anymore.
Just had the meeting with the solar salesman. Here are the options and decisions I have to make:
Enphase micro inverters or a Tesla macro inverter
Tesla Pros
More efficient, so better production from same panels
Somewhat cheaper
Integrate with our existing app for the car
12 year warranty
Enphase
25 year warranty
estimated 350kWh/year less production
Musk free design
Discount
20% off, act now, limited time!
30% commercial tax rebate
selling the power to the utility makes it a commercial enterprise
Supposedly 42% of residential customers have used this option
Any opinions?
The macro inverter takes panels down in blocks of three, so if one of them fails, I only lose three. The panels also can turn off individual cells if they are shaded, So the mentioned concerns about issues with a single inverter are “based on old technology.”
They fill out the tax forms to claim the commercial credit. It does not involve creating an LLC or anything. The difference between 20% and 30% is about $2000, so not trivial. Just paying less up front is obviously much simpler, and worth something.
(Disclaimer: Sharing some opinions & questions, but I have been out of the game for a bit, so it’s possible the installer knows stuff I don’t)
The inverter itself is more efficient? And that offsets per-module power optimization (that you get with micros)? Hmm. I find that a bit hard to believe, but not impossible.
Are you sure you got that number right? The average US household uses about 900 kWh/mo, so that’s not a whole lot of production difference… about 12 days’ worth?
How does the Tesla inverter disable panels? Are they wired in strings of three, or is there some sort of control system in each panel that lets the inverter actively communicate with them to signal a disconnection?
With a micro-inverter, you only lose one (or part of one) module at a time, instead of three. If you have frequent shading (i.e. nearby trees or other obstructions, or it’s often cloudy) that can be beneficial. If your view of the sky is almost always clear during the productive hours, not a huge deal.
Hmm, that’s new to me — it’s possible, I’m just not very familiar with Tesla’s offerings. How do they do that? Is it bypass diodes, or some other technology inside the modules (panels) themselves?
Do the modules have module level electronics (like a small power optimizer type thing) built into them already?
IMHO: As much as I dislike Musk, a string (macro) inverter is far simpler to install and replace later on, since you don’t have to climb up on the roof and replace individual micros/power optimizers under each modules. In that case it’s just a bunch of modules and cables on the roof, and all the fancy smart electronics are inside the house, where they’re more easily accessible.
But if these are special modules with their own active electronics attached (to enable the inverter to control them better), then you lose some of that simplicity.
What? That makes no sense to me, but maybe I’m misunderstanding. Every grid-tied residential solar install “sells power to the utility” in some way, or at least gets credits for it. Are they all commercial installations now…? Or is there something in your state that makes this possible…?
Just repeating the salesman’s pitch, so these could be wrong.
The inverter itself is somewhat more efficient, but there are also gains in using DC transmission from the panels to the inverter, rather than AC from the panels. That is because it’s easier to combine multiple DC streams into a single stream, than combining multiple AC streams, so less power loss in the “bundler.”
When I asked how much is “more efficient”, the calculation was about 350kWh, or 3.5%, so about 40% of a winter month (gas heating), so yeah, 12 days.
The panels are controlled in threes, but 100% coverage is a prime number of panels, so I don’t know if that means 4-threes and 1-five, or if they’ll just do the three roof sections as their own zones. Adding another panel would be about $1200, but then 3 would be a prime factor.
As you say, bypass diodes are used to shutdown parts of panels if they’re underproducing.
In the initial design, 8 of the 17 panels are on a 2nd floor south facing roof, so no shading, and optimal direction. 5 panels are on a south facing first floor roof, with some possible shading, and 4 on a first floor west facing roof, with no shading.
And yeah, I’m suspicious of the tax thing. He claims 42% of residential customers use the commercial deduction, which I also don’t understand, because the only reason to use it residentially is if, just for example, the commercial tax break lasts an extra six months.
I also just found out that there is an extra $750 fee associated with using the tax option; I assume for the tax preparation that is done. So doing the tax option could potentially save me $1150. The downsides are I won’t see any of the money until probably April, 2027, and it could prevent me (or my wife) from being appointed to one of the federal reserve boards (not that we’re in the running).
Our gracious financial backer doesn’t seem to care one way or the other about the difference in cost. She was budgeting $20k, so if the whole thing is $15k, she’s happy.
