Next: We have Solar at Home Part 3
Previously: We have Solar at Home Part 1.

Question	Estimate from April 2022
How much electricity will we use between 2023 and 2032?	between 3217 and 5835 kW·h per year
How much will PG&E charge for that electricity?	$0.43 per kW·h, increasing 7.6 percent per year
How much will the system cost to install and operate?	?
How much electricity will the system generate?	?

How much will the system will cost to install and operate?

I had no idea. I knew solar panel prices had collapsed since my childhood; I’d seen graphs like this:

Evolution of solar PV module cost by data source, 1970-2020. X axis is timeline from 1975 to 2020. Y axis is USD (2015) per Watt, from 0 to 120. Data points start around 105 in 1975, drop linearly to about 45 in 1978, and then in a curve down to about 8 in 1987, and then mostly linearly to 4.2 in 2008, steeper to 1 in 2015, and then linearly to 0.2 in 2020. The dots are colored; most are yellow but after 2010 they are blue. Some years have multiple dots, some mostly overlapping and some further apart, but none are inconsistent with the pattern. Blue is Bloomberg monocrystalline, Yellow is Swanson. Other colors are rare, and include Bloomberg multicrystalline, Maycock, Reichelstein, and Pillai. Small text at the bottom: Appears in Clean Energy Innovation. Sources: Kavlak, McNerney and Trancik (2018); Bloomberg LLP (2020).

So I had a vague hope that the panels would be under $10,000, which felt extremely cheap, at least relative to other home improvement projects. Note that a 1980 dollar is worth six times more than a 2020 dollar, so any intuitions about cost over decades are very tricky. The batteries on our electric bike were over $500 each, so I knew battery storage could easily be another $10k. At the same time, I assumed we would never be able to offset all of our usage with solar. My brain was still calibrated to Jimmy Carter’s White House panels², and a general sense that solar power is very weak³. But even if solar only took a medium-sized bite out of the electric bill—which was shaping up to be hundreds of dollars a month—it could still pay for itself.

It turns out that the panels themselves were never even half of the cost.

Figure 17: NREL residential PV system cost benchmark summary (inflation adjusted), 2010–2020. Y axis is 2019 USD per Watt DC, from $0 to $8. The 2010 bar is $7.53, which drops steeply to 4.67 in 2012, and then slowly to $2.71 in 2020. The top bar is black and white cross-hatched, labeled Soft Costs Others (PII, Land Acquisition, Transmission Line, Sales Tax, Overhead, and Profit), and drops from about $3.5 in 2010 to under $2 in 2020, going from one third to one half of the total. The yellow bar, Module, goes from about $2.60 in 2010 to about $.30 in 2020. Other bars include Soft Costs – Install Labor, Hardware BOS – Structural and Electrical Components, Inverter, and Additional Costs from Model Updates*.

⁴

Panels got 90% cheaper in a decade, but total cost only dropped 60%, so the overall project savings are diluted compared to, say, giant TVs. On the other hand, modern panels are very efficient. If we covered the entire roof, we’d generate far more energy than we could use. You might think generating more clean power is a good thing, because if we can’t use it someone else can. This is our cue to talk about regulatory capture.

No, just kidding, you can read about regulatory capture from many better sources. Just take it as given that the leadership of the California Public Utilities Commission has favorites among its constituencies⁵. California passed a law in 2013⁶ that created NEM2. The meaning of NEM2 for our purposes is, we can connect solar panels to the grid, and PG&E has to let us, and they have to buy back our excess electricity if we have any. I’ve heard that they have to pay market rate for it, which would between $0.3 and $0.6 per kW·h, but I’ve also heard they only have to pay a few cents for it. The power companies got NEM2 replaced with NEM3, which is a much worse deal for solar panel owners, but we—meaning the vendor—got our paperwork in half a year to spare, so we will remain legacied⁷ under NEM2 for 15 years. Either way, it’s apparently in our financial interest to make exactly as much solar as we need, so we don’t want to get the 30 or more that would fit in the square footage of the roof.

We—meaning the vendor—sketched numbers for 9-panel and 12-panel arrangements, and their roof guy came with a big ladder and climbed around taking notes.

A flat roof surfaced in dirty gray material. A person in the middle ground wearing a dark jacket, dark jeans, boots, a gray baseball hat, and a black facemask, with light-colored hands and neck and ear visible, looking down and holding a yellow tape measure extending diagonally to the roof surface. Fairly shallow, very sharp shadows are visible to the left of the person and around of few pieces of pipe tops on the roof. Two skylights are visible on the right foreground. The roof ends about 10 feet beyond the person. Another building extends further on the right, about half a floor taller. A tree fills most of the background. Behind the tree a ridgeline with some trees and many terraced houses is visible, stretching from the right edge of the photo, behind the tree, to a hill in the top left corner, topped by a few trees, a green and brown area, and then multiple concentric rings of terraced houses. The sky is very light blue and cloudless.

As it turns out, the skylights, pipes, vents, access walkway, and setbacks⁸ together block more than half the roof …

A rooftop fills the bottom third of the rooftop, with a dirty gray surface and a scattering of shiny metal pipe tops and exhausts. Above the roof, a thin line of houses and patches of tree extends across the picture. Aobev that, on the left side, a stretch of blue water with a flat horizon. On the right side, the water disappears behind hills, and on the far side of the water, a ridge line emerges from the water and extends above the nearer hills to the edge of the picture. The top half of the picture sky shading from light blue up to a medium and rich blue at the top. The sky is cloudless except for one contrail streaking faintly from the top left corner, fading out before reaching the middle of the picture. Very dark shadows extend briefly below some of the tops of the roof objects.

… so we can’t go much above 12 anyway⁹.

A black-and-white plot of a rooftop. A rectangle filled with many smaller squares and circles. A number of big blue squares sit in clear areas.

With NEM2, if you have no battery, the solar power goes directly back to the grid. You don’t actually use your own solar power; you just have something on the roof that lowers your bill. If PG&E goes out, we go dark. We can accept that for now, but if PG&E’s already mediocre reliability drops further¹⁰ ….

The vendor provided two cost estimates, 9 panels for $17,000, and 12 panels for $20,000, and we planned for a 24% non-refundable tax credit, so the cost would be $12,920 or 15,200¹¹. The systems generally don’t need cleaning or any other maintenance, so operational costs should be um … zero? If we need to do something to the roof, the company will remove and re-install the panels at no extra charge. Once.

So ~~$12,920 or $15,200~~¹² $17,000 or $20,000 is the third of four answers. Tune in next week for the last question, How much will the system offset our usage?. Bonus: I’ll tell you a Homeowner Horror Story. It’s called, The Dryer That Didn’t Get Used For Six Months.

Next: We have Solar at Home Part 3

IEA, Evolution of solar PV module cost by data source, 1970-2020. (2020). iea.org. ↩︎
Which were not electricity-generating. They were thermal panels, heating water to use in the House, offsetting the water-heater bill. ↩︎
This thought reveals some nasty assumptions and biases toward hippie-punching that my brain must have been washed with by the culture I grew up in. Remember kids, Strong is Right and Weak is Wrong! ↩︎
David Feldman, Vignesh Ramasamy, Ran Fu, Ashwin Ramdas, Jal Desai, and Robert Margolis, U.S. Solar Photovoltaic System and Energy Storage Cost Benchmark: Q1 2020. National Renewable Energy Laboratory Technical Report NREL/TP-6A20-77324. ((2021-01). nrel.gov. ↩︎
Some of those that need voters
are the same that heed donors
with abject apologies to RATM^א. ↩︎
AB 327 ↩︎
The common term is grandfathered, but that has a gross origin. After slavery was partially outlawed in the US, White supremacists needed new methods to keep Black people disempowered. They did so by passing laws adding qualifications to voting such as poll taxes and literacy, which kept poor people from voting, and then exempting anyone whose grandfather or other ancestor had voted in the past, i.e., poor Whites.
It’s a very useful term with few synonyms, so I’m carefully avoiding researching the word legacy. ↩︎
SF requires that residential solar panels not be visible from the front of the house^ב. But when we ordered fiber-optic internet, the company came out and strung a new cable across the street without, so far as I know, even notifying the city. Legacy.

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Spoiler alert: As you can see from the Plan we—meaning the vendor—made, we ended up with 14 panels, and probably couldn’t have added another. ↩︎
A fractal portion of the Sunset, affecting thousands of people including us, blacked our three or four times recently, for hours at a time or more. Not related to any storm or heat event. The shape suggests equipment or computer failure, and the repeat outages of various sizes following the same pattern suggest recurring under-investment. Not to mention the days when the power went off for one second. Every hour or so. All evening^ג. Here’s a map of one of the smaller ones.

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You may be wondering how we could calculate that without knowing the marginal tax rate. Let’s check our knowledge on tax credits vs tax deductions. A tax deduction means you don’t have to pay taxes on that amount of income. So if you are paying 20% income tax on $100,000 annual income, and you can deduct $10,000, your total income tax drops from $20,000 to $18,000.
It’s more complicated, of course, because the U.S. uses a marginal tax system. Let’s say there are two rates, 10% up to 50,000, and then 20% for anything above that^ד. Say you have $100,000 of income: half will fit into the first bracket and be taxed for 10%×50,000= $5000. The rest goes into second bracket, taxed for 20%×50,000=$10,000. You owe $15,000.
If you had a $10,000 deduction, you would have only $40,000 in the second bracket, taxed for 20%×40,000=8000, and your total tax would be $13,000 instead of $15,000. So the $10,000 deduction reduces your income tax by $2000. Which is nice, but not as nice as $10,000.
We can now flip this around by remembering that buying something that saves $1 of tax is the same as paying $1 less for that thing. Let me pause to convince myself of that: paying $20,000 for something is not the reason we pay income tax. We pay income tax on the $20,000 in taxable income that we earned working at the car wash this summer. If we spend all of that money on something non-deductible—let’s say we buy three nice cashmere shirts from a celebrity clothing line—then we pay normal income taxes on the $20,000. But that amount depends on our marginal tax rate, so you don’t know how much you owe on that $20,000—of income—until you know your total income for the year and all of the other deductions you are taking.
In order to escape this footnote, assume we—meaning you, I guess—are single and our—your—total income is $300,000. The bracket goes from $231,250 to $578,125, so 20k isn’t going to make a difference. Therefore, for the portion of our income that we used to buy the shirts, we’ll pay 35%×20000=$7000 in income tax.
But. If we spend our earned income on something tax-deductible, then we don’t have to pay the normal taxes for that original $20,000 of income. If instead of buying those shirts we donated 20,000 to Samuel Alito’s Mom’s Satanic Abortion Clinic™^ה, we wouldn’t have to pay any taxes on that original $20,000 of income, so spending $20,000 that way would reduce our tax bill by $7000^ו.
Not all deductibles are 100%. If we spent it on something with a 30% deductible, we would deduct 35%×30%×20,000=$2100. That’s effectively the same thing as paying $17,900 for a $20,000 system. But that’s with a 30% deduction. With a 30% Credit, we’d save 30%×20,000=6000 and the marginal tax rate doesn’t matter. Let’s talk about why in a footnote on the next page. ↩︎
I apparently left that credit out of our forecasts, which biased them by three to four thousand dollars against solar. ↩︎

Some of those who work forces
Are that same that burn crosses
—Killing in the Name.
The contractor told us this, although I've researched it for over 10 minutes without finding confirmation. The SF Building Code doesn't seem to mention it.; I haven't been able to verify it in over 8 minutes of research. Interestingly, the county claims copyright over that document; the Supreme Court ruled in Georgia Et al v. Public.Resource.Org that state legislatures, at least, cannot copyright "the works they create in the course of their official duties".
Hood above the stove: hold the power button about 2 seconds, then + and − for the hour, touch power again, do the seconds, touch power again. Can do 24-hour time. For the stove, touch the clock icon, type in the type on the numeric keypad, touch the clock icon (this one doesn't sound quite right; will have to test and practice). Doesn't do 24-hour time. Kitchen microwave: crummy lcd, don't bother. Kitchenette microwave: Hold the Clock icon for 3 seconds, enter the time in the numeric keypad, push the clock again? Fuzzy. Doesn't do 24-hour time.
In 2023, the system had seven brackets: 10% on the first $11k, then 12% on the next 33,724, and so on up to 37% for any income over $578,125. If you are single. The most common misconception is that an increase in income that raises your total into the next bracket will reduce your total income, which is not possible from marginal tax rates. Marginal rates mean, whatever amount of income is in the higher bracket, gets taxed more. The IRS has a chart to show this, though not very well.
Yes, it's real.
Yes, it's 100% tax-deductible. It's a 501(c)3. irs.gov. In a sense, the $7000 'comes from' all other taxpayers. We are collectively subsidizing the charity.