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Cost of Tesla Solar Roof Tiles
- Thread starter Green Pete
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brucet999
Active Member
The primary problem with the estimator is that it is assuming that the "whole roof + battery will qualify for the 30% tax credit". In some installations, some non-producing tiles are used and are still calculated into the tax credit - I don't know how well this will hold up once the IRS sees people taking large tax credits on the roof in a dual-use scenario - especially for roofs which are not producing throughout the 2D space.
What is everyone thinking in terms of the taking of the tax credit on a roof that is perhaps only 50% solar shingles, the remainder are just "to look like" the solar shingles?
What is everyone thinking in terms of the taking of the tax credit on a roof that is perhaps only 50% solar shingles, the remainder are just "to look like" the solar shingles?
I don't think that's correct. It said somewhere on the site that the tax credit is based on the proportion of the roof that is solar tiles.
Yinn
Active Member
I was optimistic but I just don't see them getting close. Half of my front roof was estimated at $12,000 to replace. The same is estimated by their calculator at $72,000. Even with the 30% credit, that's $40,000 more.
Over a 20 year timeframe, it would need to generate $166/mo or 1mWh/mo in my area just to break even.
Maybe he meant it was cheaper than getting a roof + a solar system put on top of that new roof.
SageBrush
REJECT Fascism
I gather that the cost to install a regular tile roof is $6 - $10 a square foot
If a PV tile has ~ 12% efficiency, a square foot will have a rating of about 11 watts
Conventional PV can be up to $5 a watt, or $3.5 after the federal tax credit
So the PV component of the Tesla tile is worth up to ~ $37
Taken together, a Tesla PV tile breaks even with conventional+PV at the $41 - $47 per S.F range
I think they are there, so it is a VERY attractive money and aesthetic choice for people who want tile roofs.
Tesla also includes removal of the old roof in their price; I'm not sure if conventional tile installers do the same.
If a PV tile has ~ 12% efficiency, a square foot will have a rating of about 11 watts
Conventional PV can be up to $5 a watt, or $3.5 after the federal tax credit
So the PV component of the Tesla tile is worth up to ~ $37
Taken together, a Tesla PV tile breaks even with conventional+PV at the $41 - $47 per S.F range
I think they are there, so it is a VERY attractive money and aesthetic choice for people who want tile roofs.
Tesla also includes removal of the old roof in their price; I'm not sure if conventional tile installers do the same.
However the calculator does not account for shading issues caused by trees, neighboring buidings, roof facing direction, etc. By assuming down based on some basic aspects - they do compute lower "percentage" however, it won't care if it is north/east/south/west facing or if there is shading causing efficacy loss. I used to say "The federal tax credit applies even if you install a solar pv system in your basement". Here, we presume that "good sun" is not required for an installation. I do think that the IRS needs to review these for value. Some cases, the tax credit will be given in a larger sum than an actual full Solar PV system would cost to install in its entirety. All for the "looks" of the system. the IRS is not into paying for vanity but in this case, it will be.
Primary competitor to the roof is Solar City installing high efficiency, perhaps Chinese, modules on a roof facing due-South only, making roughly the same power as most of a roof installed using solar shingles and at a price at least 1/3 of the roof's solution.
My main beef is the gaming of the IRS credits to "help pay for" the higher-price of the roof and it's dual-use treatment that overnight-charged batteries faced with the IRS for their arbitrage use. The IRS said it was not in the business of paying for electricity arbitrage using the DoE renewables incentives. It also is not in the business of paying extra for a "good looking roof". We know people have a personal responsibility to take the correct tax credit - and I am sure that some folks will certainly take 30% of the entire roof's installation price in order to help pay for it. Most likely will get away with it unless the auditors find it worthy of their time to inspect the installation. Keep in mind that the roof was not planned by Tesla until the 5-year extension was assured by the federal government. There was no talk of roofs prior to the extension. Now, that 30% can be used as "meaty incentive" to help sell it.
The estimator also would ignore inverter replacement of a string inverter typical in years 13-15 (so two new inverter installs over 30 years. If using a powerwall for daily cycling (which may be common in California) you also face a replacement after roughly 15-20 years, perhaps sooner. Warranty is only thru 10.
Find a neighbor's house in your area with heavy shading. Put it into the system as an installation address. See what Tesla "assumes" the value of power will be and then decide for yourself.
I just did this. Heavy East shading, roof facing west. estimator says to only install 50% of the roof. Roof Cost 56,300 with tax credit of 13,400 - that is a 23% tax credit so it's absolutely not using the 50% of the cost ratio but a much higher number. 30% of 50% of 56300 is (56300 / 2) * .30 = 8445
Is the estimator over-stating the tax credit from its calculations?
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I think 10% efficiency would be good. About half the efficiency of the best panels, yet you see no panels.
SageBrush
REJECT Fascism
The PV tile is ~ $42 a square foot and the matching non PV tile is ~ $11 a square foot.
Take the PV tile, put it in the shade, garner the 30% tax credit, and only pay $29.4 per square foot.
There are better ways to game the IRS
Also, does the IRS consider those using battery backup only for a powerwall capable of taking it as a 30% credit? Aren't they supposed to be cycled often? The SGIP requires 52 cycles a year and will request proof. Fed govt has no proof gathering organization so it is ripe for abuse. The nebulous nature of this industry seems to offer ways to gain favorable credits.
Unless someone is in a power arbitrage situation, seems batteries may not be properly used to qualify for the itc unless someone is just cycling batteries daily because they are there. That effectively wastes power during the round trip charge discharge.
When is Energy Storage Eligible for the 30 Percent ITC?
Unless someone is in a power arbitrage situation, seems batteries may not be properly used to qualify for the itc unless someone is just cycling batteries daily because they are there. That effectively wastes power during the round trip charge discharge.
When is Energy Storage Eligible for the 30 Percent ITC?
brucet999
Active Member
I don't think that would be such a problem. In conventional solar panel arrays, each panel is connected to an optimizer or micro inverter. Typically rooftop solar panels are made up of 40 cells, so up to 40 Tesla tiles might be wired in series with one optimizer to equal the effect of one panel. From the apparent structure of the flat Tesla tiles, I would guess that each has two connectors at the top edge, so they can be daisy-chained together in strings that are then connected to an optimizer and thence to the inverter.
Each string of tiles in a course on the roof would have just enough space under the next overlapping tile for a wire to run horizontally to the next tile. The first and last end connections of each course would have to penetrate the roof in order to reach optimizers or the next course of tiles. If an extra piece of roofing felt overlaps each of the roof-penetrating wires and underlaps the course of felt above, then the water shedding integrity of the roof would be preserved. In the case of plastic underlayment instead of felt, a piece of adhesive-backed Ice & Water shield could be applied over each wire penetration to preserve water shedding integrity.
mmd
Active Member
Finally someone gets the math right on the solar roof tiles.
Why Tesla's Solar Roof Is A Bad Buy
Here is the Solarworld hail test from 2013 (link in that article):
Why Tesla's Solar Roof Is A Bad Buy
Here is the Solarworld hail test from 2013 (link in that article):
Wow, they really don't get it. It's true that after 30 years, the solar roof will likely produce irrelevant amounts of energy. At that point, you could just write off the solar, and install panels on the roof. The roof is still fine - you just need new solar. And they compare to asphalt, without adding a couple of replacement roofs over a 30 year period.
Not usually. Most arrays are just wired to a central inverter. Optimizers and microinvetrers are placed behind the panel. Not sure how Tesla is doing optimizers with this new roof.
brucet999
Active Member
My answer was to the question of Tesla Roof handling partial shade, a situation that requires micro inverters or optimizers.
I know that arrays can run on straight strings if there is no shade and all panels are on the same sun aspect, but such installations will be governed down to the lowest performing panel. One lower performing panel, a failed panel, or even a very dirty panel (the one that flock of starlings favors
) will bring down the output of the whole array to match the poor performer and there is no way to monitor performance of individual panels.If there is a Power Wall in the installation, then only optimizers would make sense, since, as someone posted above, it makes no sense to invert DC to AC and then rectify it again to DC to charge the battery. If you install a single inverter such as the one Tesla uses, capable of automatically disconnecting from the Grid in case of a grid power outage, then optimizers are the better choice.
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brucet999
Active Member
I think they do get it. In the example, for the same PV output, Butch saves $13,600 with conventional roof and solar panels. Assuming that all his panels can be hidden on the back roof surfaces, there would be no esthetic penalty (assuming that asphalt shingles look ok to you) to panels and there is still about 40% more savings than the cost to re-roof.
As to installing solar panels when the Tesla tiles have lost their productivity, that would be hugely more expensive than just replacing panels on an already installed rack system.
Asphalt shingles certainly don't look especially appealing. They're somewhere between "meh" and "yuck".
I hardly see *any* asphalt shingle roofs in Norway. We're not that poor. Well... More accurately, labour is expensive, so replacing a roof often is *waay* more expensive than using higher quality materials.
Using Decra (pretty much the cheapest common roofing), can easily cost 1000-1500 NOK/square meter professionally installed. For 2000 square feet, that's 23-34k USD. It goes up from there.
I hardly see *any* asphalt shingle roofs in Norway. We're not that poor. Well... More accurately, labour is expensive, so replacing a roof often is *waay* more expensive than using higher quality materials.
Using Decra (pretty much the cheapest common roofing), can easily cost 1000-1500 NOK/square meter professionally installed. For 2000 square feet, that's 23-34k USD. It goes up from there.
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