Updated with a lot of things.
Bill suggested I put $15k into an investment account of some kind. Ok. Let's say I can get 10% annually on my money through some investment mechanism. Now we have two scenarios:
1) Invest that $15k into a fund, earning 10% annually.
2) Invest my solar payments into the same fund, earning 10% annually.
With these scenarios, I break even at year 9.5, with the solar situation matching the no solar situation.
By year 15, I am $17.6k ahead with the solar.
By year 25, I end up with $259.6k with solar and the investment, compared to $169k with the investment only.
After year 15, National Grid drops the negotiated $0.3125/kWh buy back rate. My model (and RGS's model) assumes they will pay 1:1 for my electricity compared to my cost from them. If they pay something less than what I can buy it for, it will begin to make sense to store some of the energy I create with the panels for consumption within my home. That way the grid is factored out. The less they pay, the bigger the storage medium required, up to 100% of what I can generate. I can generate an average of 19 kWh/day from year 15 to year 25. So I'd have to store that to use it all. So you'd have to add the cost of up to 19 kWh energy storage at year 15. Most likely the grid will pay something, and I can get a battery/storage system that stores less than 100% of what I make. While that will decrease my 25 year return, it is guaranteed to be ahead of the investment by itself because, again, it is $90.5k ahead by year 25.
Solar ROI for my house
Re: Solar ROI for my house
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Re: Solar ROI for my house
Spoke to Ed for an hour and 15 minutes this afternoon. We covered many topics.
Cyber
He has an action to get back to me. To understand the cyber risk, he is going to find out if the inverters can be configured or otherwise controlled via their remote interface. Naturally this system is web connected and I get performance and health info via the web portal. That's fine. But can the inverter settings be changed or otherwise controlled via the web? Let me spell out the risk: without talking to a product engineer, it seems to me a malicious actor could accomplish one or more of the following:
1) Remotely disable my inverters (they do have an auto shutdown when the grid is down but that is automatic)
2) Remotely change inverter settings. Output voltage, frequency. Maybe this trips breakers (nuisance). Maybe, worst case, this causes a fire. I would bet the inverters have a safety shutdown but I am capturing this since I thought of it.
Ideally, that kind of thing can only be done locally. OR, that kind of thing isn't done at all, and these are 100% automatic with no configuration possible or required. Then it would really just be a one way thing about production, panel health and so on. I suspect it is automatic, as the frequency would automatically match the grid (no configuration possible or necessary). And the output is a function of grid voltage and panel output. Again, automatic. So if I had to take a guess, I'd assess the cyber risk as very low.
Promo
They'll give me 3 months of my annual electricity bill as a discount to system purchase. In my case that works out to about $390. That is, if I sign up in December. It is hard to be swayed by $390 given the other costs and extremely long time horizon of this whole ordeal. Still, $390 is $390.
Metering
As I figured out before, it is a dual meter situation. For the first 15 years I simply sell back everything I make for $0.3125/kWh.
The model
We spoke at length about the model. One thing I didn't notice before but he put a solar factor (which is kind of just another efficiency coefficient) of like 92% so yet again, some conservatism injected, like the derating of the panels over time. Speaking of which, we talked about that. He is actually pretty adamant that the panels just don't stop working at year 25. Or even year 30. Their performance may continue to slide but they will keep making power. So rather than the whole system becoming trashed, you just replace panels that are unacceptably low performing. Again, with the inverter setup, a poor performing panel doesn't take down the entire string. This all bodes well for the long term in my opinion.
We also talked about what happens after year 15. This is where I need to talk to National Grid. I think the model is a bit too optimistic here. Here is how he described the current rules when you are not under a sell-back contract (this is how his system currently works as he installed it before this kind of sell-back agreement existed):
- He still sells back power to the grid as produced
- If more power was produced in a given month than used, he is issued a credit for that power
- If that power is needed within the same month it was produced, it is just a 1:1 transfer
- If that power is needed in another month (or say from summer to winter), then he has to pay a distribution charge on his power credit. This reduces his power credit by about 50% or whatever the ratio of distribution to electricity is. This is because the grid "stores" your electricity so to get it back, it has to be distributed back to you.
- He was told, but was going to inquire (or maybe I will), that if he ends up producing more than he uses on an ongoing basis, you can request your credit in the form of a check.
Anyway I need to see if I can get the model to reflect this. He has a chart of my electrical consumption vs panel production on a monthly basis. I can study that and see if I can make sense of this and get a better value for those out year electrical savings. It will go down. But again, that 50% distribution charge is only for the credit used across 2 or more months. I will think about this and put something into Excel.
Cost
He didn't know the exact breakdown but did say those aluminum tracks with the flashing mounts would be in the $1500 range. $500 for the Enphase Envoy gateway monitor thing. Another $1000 for misc wiring and the meter? Plus the 8 grand for the panels and inverters. $11k materials and $11k labor?
Cyber
He has an action to get back to me. To understand the cyber risk, he is going to find out if the inverters can be configured or otherwise controlled via their remote interface. Naturally this system is web connected and I get performance and health info via the web portal. That's fine. But can the inverter settings be changed or otherwise controlled via the web? Let me spell out the risk: without talking to a product engineer, it seems to me a malicious actor could accomplish one or more of the following:
1) Remotely disable my inverters (they do have an auto shutdown when the grid is down but that is automatic)
2) Remotely change inverter settings. Output voltage, frequency. Maybe this trips breakers (nuisance). Maybe, worst case, this causes a fire. I would bet the inverters have a safety shutdown but I am capturing this since I thought of it.
Ideally, that kind of thing can only be done locally. OR, that kind of thing isn't done at all, and these are 100% automatic with no configuration possible or required. Then it would really just be a one way thing about production, panel health and so on. I suspect it is automatic, as the frequency would automatically match the grid (no configuration possible or necessary). And the output is a function of grid voltage and panel output. Again, automatic. So if I had to take a guess, I'd assess the cyber risk as very low.
Promo
They'll give me 3 months of my annual electricity bill as a discount to system purchase. In my case that works out to about $390. That is, if I sign up in December. It is hard to be swayed by $390 given the other costs and extremely long time horizon of this whole ordeal. Still, $390 is $390.
Metering
As I figured out before, it is a dual meter situation. For the first 15 years I simply sell back everything I make for $0.3125/kWh.
The model
We spoke at length about the model. One thing I didn't notice before but he put a solar factor (which is kind of just another efficiency coefficient) of like 92% so yet again, some conservatism injected, like the derating of the panels over time. Speaking of which, we talked about that. He is actually pretty adamant that the panels just don't stop working at year 25. Or even year 30. Their performance may continue to slide but they will keep making power. So rather than the whole system becoming trashed, you just replace panels that are unacceptably low performing. Again, with the inverter setup, a poor performing panel doesn't take down the entire string. This all bodes well for the long term in my opinion.
We also talked about what happens after year 15. This is where I need to talk to National Grid. I think the model is a bit too optimistic here. Here is how he described the current rules when you are not under a sell-back contract (this is how his system currently works as he installed it before this kind of sell-back agreement existed):
- He still sells back power to the grid as produced
- If more power was produced in a given month than used, he is issued a credit for that power
- If that power is needed within the same month it was produced, it is just a 1:1 transfer
- If that power is needed in another month (or say from summer to winter), then he has to pay a distribution charge on his power credit. This reduces his power credit by about 50% or whatever the ratio of distribution to electricity is. This is because the grid "stores" your electricity so to get it back, it has to be distributed back to you.
- He was told, but was going to inquire (or maybe I will), that if he ends up producing more than he uses on an ongoing basis, you can request your credit in the form of a check.
Anyway I need to see if I can get the model to reflect this. He has a chart of my electrical consumption vs panel production on a monthly basis. I can study that and see if I can make sense of this and get a better value for those out year electrical savings. It will go down. But again, that 50% distribution charge is only for the credit used across 2 or more months. I will think about this and put something into Excel.
Cost
He didn't know the exact breakdown but did say those aluminum tracks with the flashing mounts would be in the $1500 range. $500 for the Enphase Envoy gateway monitor thing. Another $1000 for misc wiring and the meter? Plus the 8 grand for the panels and inverters. $11k materials and $11k labor?
Re: Solar ROI for my house
Info.
https://www9.nationalgridus.com/narraga ... st_gen.asp
Like he told me, the program is currently suspended. As with previous years, he said it will resume next year. They have a target in megawatts of system growth or something along those lines.
https://www9.nationalgridus.com/narraga ... st_gen.asp
Like he told me, the program is currently suspended. As with previous years, he said it will resume next year. They have a target in megawatts of system growth or something along those lines.
Re: Solar ROI for my house
And here is the net metering section. This is what happens when there is no agreement/tariff/PBI.
https://www9.nationalgridus.com/narraga ... et-mtr.asp
https://www9.nationalgridus.com/narraga ... et-mtr.asp
Re: Solar ROI for my house
So how long do solar panels last anyway?
Based on some initial research, a pretty damn long time.
https://cleantechnica.com/2015/10/19/ho ... nels-last/
NREL study: http://www.nrel.gov/docs/fy12osti/51664.pdf
30 year plus panel: http://www.greenbuildingadvisor.com/blo ... aic-module
https://solarreviews.com/solar-panels/h ... nels-last/
This provides some info on that NREL analysis/report.
Oh look
Discuss.
Based on some initial research, a pretty damn long time.
https://cleantechnica.com/2015/10/19/ho ... nels-last/
40 year panel: http://cleantechnica.com/2011/12/27/sol ... -20-years/Most solar panels used in home solar arrays come with a warranty for some 25 or 30 years, which means that the solar panels are guaranteed for decades, unlike many of the other goods we buy. And again unlike many other consumer goods, they don’t ‘give up the ghost’ at the end of their warranty period and need to be replaced, but continue to still produce clean electricity, although at a slightly less efficiency each year. In fact, some decidedly old-school solar cells have been producing electricity daily for about 40 years or so, and are expected to continue to power homes and businesses for decades more.
According to a study undertaken by the National Renewable Energy Laboratory (NREL) a few years ago, which looked at the ‘photovoltaic degradation’ rates of some 2000 solar installations, the average solar panel loses about half of a percentage point (0.5%) of efficiency per year, which means that a panel at the end of its 25-year warranty period should still be operating at about 88% of its original capacity. However, not every panel will see degradation rates as high as 0.5%, as shown by this 30+ year old solar panel, which outperforms its original specs, even after decades in the sun.
NREL study: http://www.nrel.gov/docs/fy12osti/51664.pdf
30 year plus panel: http://www.greenbuildingadvisor.com/blo ... aic-module
https://solarreviews.com/solar-panels/h ... nels-last/
https://www.engineering.com/Electronics ... Panel.aspxI think consumers can be confident about these panels lasting at least 25. The reason I say this lies in the core make up of the cells. Crystalline cells are made from wafers that are in turn cut from silicon crystals (that are hard rocks). Given these are then covered by glass (or other clear covering) and protected from water and wind (the normal things that weather rocks) I think it is very likely that these cells could last 50-100 years.
This provides some info on that NREL analysis/report.
This all jives - they usually out perform the warranty guarantee.For monocrystalline silicon, the most commonly used panel for commercial and residential PV, the degradation rate is less than 0.5% for panels made before 2000, and less than 0.4% for panels made after 2000. That means that a panel manufactured today should produce 92% of its original power after 20 years, quite a bit higher than the 80% estimated by the 1% rule.
Oh look
As low as 0.2% per year!!Crystalline silicon modules located in extreme climates showed high degradation rates. For very cold climates, panels subjected to heavy wind and snow loads suffered the most. On the other hand, panels in similar climates that were installed in a facade, eliminating the snow load, had very low rates of degradation. At the other extreme, panels in desert climates exhibited large decreases in production over time - close to 1% per year - mainly due to high levels of UV exposure. Panels in more moderate climates such as the northern United States had degradation rates as low as 0.2% per year. Those panels could retain 96% of their production capabilities after 20 years.
Right. So I don't know if good quality solar panels EVER only lasted 20 years. This is very interesting. Tinfoil hat mode: The oil and gas industry perpetuated that rumor because that's what most people think even though they have zero data. A commonly held belief is not evidence of its truthfulness. Remember that.Like everything in engineering, we always assume the worst and hope for the best, so overestimating the degradation rate isn’t necessarily a bad thing. On the other hand, we want realistic estimates so we don’t scare away potential customers who think they’ll need to replace their modules after 25 years.
Discuss.
Re: Solar ROI for my house
My insurance agent said no premium increase, and it is covered. That's definitely good news.
Re: Solar ROI for my house
May need to rerun those numbers soon: https://www.washingtonpost.com/news/won ... 3c7b4f59cc
Re: Solar ROI for my house
For the record the salesman I've been dealing with has mentioned this more than once. Of course, when a salesman says "the time to act is now" it is very hard to see through the marketing BS. Sometimes, though, it is actually true.
The way I see it, solar either makes financial sense, or it doesn't. And this will remain true through all time. I also really have trouble believing it will permanently shift from the affordability sweet spot, to out of that sweet spot. It makes no sense, UNLESS the technology itself is actually not commercially viable (for residential applications). It may mean that there is a several year gap between favorable ROI. But in the long run I have a very difficult time believing that in 5 or 10 years, solar wouldn't make even more sense than it does now, and perhaps without subsidy. Again, if that is NOT true, then the technology doesn't deserve to survive.
I also question if I had signed a contract in Dec, would these tariffs have impacted me. I think they would have, provided the panels were actually purchased after the tariff turn on date. Also the tariff rolls back in the outyears.
The panels were from Silfab, a Canadian manufacturing company. I don't believe Canada is treated any differently than China in this scenario.
The way I see it, solar either makes financial sense, or it doesn't. And this will remain true through all time. I also really have trouble believing it will permanently shift from the affordability sweet spot, to out of that sweet spot. It makes no sense, UNLESS the technology itself is actually not commercially viable (for residential applications). It may mean that there is a several year gap between favorable ROI. But in the long run I have a very difficult time believing that in 5 or 10 years, solar wouldn't make even more sense than it does now, and perhaps without subsidy. Again, if that is NOT true, then the technology doesn't deserve to survive.
I also question if I had signed a contract in Dec, would these tariffs have impacted me. I think they would have, provided the panels were actually purchased after the tariff turn on date. Also the tariff rolls back in the outyears.
The panels were from Silfab, a Canadian manufacturing company. I don't believe Canada is treated any differently than China in this scenario.
Re: Solar ROI for my house
A random quote from this article:
Everything is dynamic and nothing is forever. As the Chinese standard of living increases, they will need their own "3rd world country" in which to outsource their manufacturing. This shouldn't be news to people. This is a normal economic cycle. Which is why it makes no economic sense to impose some labor union directed minimum pay for a labor skill. The pay for that skill should float with the market price/demand for that skill. Period.Manufacturing wages in China have quadrupled, in some cases more. I talked with a taxi driver in Beijing who said 18 years ago factories in his home town paid $50/month and now pay $500/month - but still not enough for him so he moved to Beijing, separating from his wife and child to earn more money. Most of China's economy now is in services - like most other countries.
China is introducing robots in manufacturing and is moving low skill manufacturing jobs to Vietnam.
Re: Solar ROI for my house
I happened to exchange e-mails with the salesman and asked about the country of origin of the panels. To my surprise, they are made in both Canada and California. Which is North America. Which I think makes them exempt of the tariff. Though he mentioned, rightly, that this will probably increase their prices. But still, that is surprising and good to know. I think some skeptics of this system assumed these would be crappy, high markup Chinese panels. Not the case at all.