We have solar power at home Part 1

Next: We have solar power at home Part 2.

In 2022, we were fortunate enough to be able to buy a house, and immediately started shopping for solar panels. Our first concern, even though we live in California, was whether we’d have enough sunshine. For example: can you see the beautiful bridge in the background of this picture?

The corner of a sunny, verdant childrens' soccer field in the foreground, with many people in the midground. A fogbank in the distance covers the top half of the picture, with a few tiny bits of blue sky visible.  Some ship masts are visible at the right edge, above parked cars and people walking on a sidewalk.

Marina Green

No, because it’s completely fogged over. Our neighborhood faces the ocean, and most summer days are pretty foggy. In this picture of a Little League baseball game taken hours before sunset in late May, when the east half of the city might still be sunny and 64°F, notice the spectators’ heavy coats. Notice also the complete lack of sunset, direct sunshine, or even blue sky.

A green, red, and white-striped baseball field at the bottom.  In the lower left, a kid in a blue jersey stands at the front of the mound.  A spectator in a blue vest stands with their back facing us on the bottom right.  Tall black wire fencing fills most of the picture, with about a dozen spectators behind it, all wearing bulky clothing and many with hats.  Behind and above the fence, a very gray sky fills the top half of the picture.

South Sunset Baseball Field #1

How well will panels still work with all the fog? What we really need is a historical baseline. Fortunately, we live next door to a five-megawatt solar plant1.

An aerial view of northern San Francisco, pointing east.  A large rectangular area fills the foreground, with one side cement-colored and the other solar panels.  A grid of houses fills the middle third, with a mountain in the top middle and a tower on top of the mountain.

Sunset Reservoir Solar Project

It’s been in operation since 2010. And it publishes its data2!

Line chart of electricity generation, from 2002 to 2024 on the X axis and 0 to 1250 megawathours on the Y axis.  A blue line starts in 2010 and jumps over 500 in 2020 and back down to zero, then peaks over 1000 in 2011, and back to almost zero, and again in 2012, then goes raggedly from 40 to 250 in 2013.  For every year following the pattern is a low around 250 in December to a high around 750 in June or July and back down.  The peaks are all somewhat jagged and slightly irregular.

Monthly energy production at Sunset Resevoir North Basin

While there’s certainly a huge swing from winter to summer, it doesn’t look like the fog makes that much difference. Our foggy concern allayed, we started doing the numbers for our roof.

Is it worth it?

Excluding externalized costs like untaxed carbon emissions, and ignoring the deeply un-Christian notions that we are the keeper of our eight billion siblings or stewards of the flora and fauna and fungi and other phyla3, let’s focus on the money. Expensive home projects are often measured by how many years will it take until the accumulated savings exceed the future value of all the money we just spent. Let’s say the upper limit of a firm yes should be about ten, according to a rule of thumb I just made up based on being born with ten fingers4 that anything longer is too uncertain for precision. And if the breakeven point is never, it’s not financially justified.

We need to know two things to calculate the breakeven point.

  • How much will we pay for electricity each year between 2023 and 2032 if we don’t get solar panels?
  • How much will we pay if we do get solar panels

We can answer those questions with four numbers.

How much electricity will we use between 2022 and 2032??
How much will PG&E charge for that electricity??
How much will the system cost to install and operate??
How much electricity will the system generate??

How much electricity will we use between 2023 and 2032?

This is hard to predict unless you’ve already been living in the house for years, using electricity in a stable pattern, in which case you can just read your own electric bills. We didn’t want to wait that long. We’d been averaging 2700 kW·h/yr in our apartment as a family of four, which is half the regional average5. (We benefit from the mild climate and also pay for it other ways.)

A vertical bar chart; the y axis is kilowatthours from 0 to 16,000, with six clusters of four bars each, blue for Northeast, red for Midwest, green for South, and yellow for West.  The clusters are 'all homes', 'single-family detached', 'single-family attached', 'apartment, 2–4 units', 'apartment, 5 or > units', and 'mobile homes'.  Midwest is much higher in all clusters while the others vary slightly.  Single-family detached and mobile homes are the highest, around 15,000 kW·h Midwest or 10,000 Northeast.  Apartments 5 or more is the lowest, at 8000 Midwest or about 5500 northeast or West

2020 Residential Energy Consumption Survey

U.S. households use almost half of their electrity to cooling air, heating air, and heating water5, but we didn’t pay for any of that in the apartment. And it had a laundry room in the basement6, and we charged our car across the street. Meanwhile the house appliances were all gas, but we’d want to switch to electricity as soon as we could. And the house came with no laundry machines, so we’d buy an electic washer and dryer immediately. So we would be adding a washer, dryer, car charging, and eventually a stove, oven, water heater, and heat pump. We guesstimated what all that would add, and came up with a range from 32176.96 to 5835.5 kW·h per year7.

How much will PG&E charge for that electicity?

Before we can estimate rates, I have to tell you about the proposal. We solicited bids from two carefully selected8 vendors, a major national company and a much smaller regional one. The national company’s salesperson argued with me over the phone. The other company came and climbed around on our roof, asked us hard questions about how we cooked our food and dried our clothes, and sent together a proposal.

Solar providers submitting applications to interconnect residential solar customers in the service areas of … PG&E, … SCE, … SDG&E, … BVES, and PacifiCorp are required to collect customer initials and a signature on the California Solar Consumer Protection Guide.9

Thus, SimplySolar’s proposal starts with twenty-two pages of CALIFORNIA SOLAR CONSUMER PROTECTION GUIDE10. Although a lot of its tips are helpful, it sounds like a close friend who worries greatly that you are marrying a mysterious stranger with a history of rich, dead spouses.

The top half of a well-formatted, illustrated page showing a gabled rooftop with solar panels on the front side, in front of a sunset, headlined CALIFORNIA SOLAR CONSUMER PROTECTION GUIDE.  The visible text includes 'Published March 2022. This guide provides important information to homeowners thinking of going solar. PUTTING SOLAR ON YOUR HOME IS AN IMPORTANT FINANCIAL DECISION. Don’t sign a contract until you read this document! What's Inside … Watch out for False Claims 2.  Know Your Rights 3. Ask Solar Providers These Initial Questions Before you Sign a Contract4.  Step 1: Is Solar a Good Fit for Me? 5

SCPG page 1

“Do you really think this Solar person is a good fit for you? All I’m saying is, don’t sign the prenup yet.”

False Claim. You can get free solar energy at no cost to you. The Truth. Solar energy is rarely free. An honest company will be upfront about all the costs you will pay over time. There is one exception: a few government-funded solar programs offer free

SCPG page 2

“Your Solar friend has promised they don’t want your money, they will pay for everything?”

Why did you choose this specific design and size for the solar system you are recommending to me? • Note that a system sized to cover all of your electricity needs isn’t necessarily the best investment. Typically, a system is sized to around 80-85 percent of your electricity use from the previous year.

SCPG page 10

“Hey, why don’t you ask your Solar friend why they want a wedding in Romania with no guests?”

What electricity provider bill escalation rate is assumed in your electricity bill savings estimate? • Note that the CPUC has capped this escalation rate assumption at 4 percent per year.

SCPG page 11


Impacts On Future Sale of Your Home Will a solar system make it more difficult for me to sell my home or refinance?

SCPG page 11

“Honey, I’m just looking out for you. Even if you survive this, will anyone sane want to marry you?”

Wait a minute—go back one, what did it say?

What electricity provider bill escalation rate is assumed in your electricity bill savings estimate?

  • CPUC has capped this escalation rate assumption at 4 percent per year.

Well that’s an odd thing. Is the CPUC protecting us from roving gangs of solar panel installers promising false savings, predicated on recklessly unrealistic utility rate-of-rate-increase forecasts of, say, over 4 percent per year? On a wild hunch, I dug up some historical rates, of 0.16082 $/kW·h on 2008-01-0111, and 0.33565 $/kW·h for 2022-03-0112. That’s over 7 percent. Interesting ….

Now we have two of the four answers. We’ll need between 3217 and 5835 kW·h per year and we’ll be charged $0.43 per kW·h13, increasing 7.6 percent per year.

Join us next week as to find out how much solar is going to cost!

Next: We have solar power at home Part 2.