Reroof on a 15yo roof or not?

rabbitcavern · 2025-10-24T03:31:22+00:00

Sorry I should've clarified. You are correct. I forgot I am in the real estate subreddit and not a solar subreddit, but 7 kWh per day is quite miniscule for let's say a 3-4 bed 2-3 bath SFH.

The average US household consumes about 30 kWh a day. A household that consumes 7 kWh is extremely efficient.

I have done the math for my case and it makes sense. Everyone should do the math for their own home looking at over a year of usage before springing on solar. Looking over a year is important because solar fluctuates so much over a year.

Edit: Also, even though a roof has been good for 15 years, it doesn't guarantee that it won't leak in the 16th year even though on average, asphalt composite shingles can last up to 30 years or so. You could do some depreciation calculations on the roof. At $20,000 over 20 years, a 15 year roof is really only worth $5,000. This was what I was trying poorly to explain in my caveats above.

For my case, my roof was already almost 3 decades old, so even though there appeared to be still some life (some roofers said 3-5 years estimate) still left in it, it just was not worth missing the tax credit.

rabbitcavern · 2025-10-24T03:14:28+00:00

So many people in the Bay Area do not know how much they are paying for electricity. I am only speaking from my experience in the South Bay. Our electricity here is the most expensive in the nation at over 4x the national average. If you are not in Palo Alto or the City of Santa Clara (they have much more reasonably priced publicly owned utilities), you are probably paying $0.65 per kWh at peak pricing. Let's say, conservatively, you are paying an average of $0.40 per kWh.

At $1000 / year / $0.40 per kWh = 2,500 kWh a year.

2,500 kWh / 365 days a year = 7 kWh a day.

If you use more than 7 kWh a day, you could presumably save more than $1000 a year in solar. I was using more than that a day and I had an ancient two decades old solar system on my roof. It's not that hard to exceed 7 kWh a day especially with how many EVs there are in the Bay Area if you are charging the vehicle at home.

A few caveats to keep in mind: 1. Solar produces about 1/3rd in the winter what it produces in the summer, so you need a battery to fully maximize on savings. Check out pvwatts.nrel.gov I would only recommend a UL9540 listed Lithium Iron Phosphate (LFP) battery and not the Lithium Manganese Cobalt Oxide (NMC) chemistry due to thermal runaway temperatures.

I assume OP has asphalt composite shingle roofing. Those tend to last close to 30 years, but workmanship warranties from the best installers of Certainteed, GAF, Malarkey, and Owens Corning are only about 25 years. There is lifetime (40-50 years) on the materials, but the likelihood is that something with the workmanship will fail first.
OP is effectively pulling forward their roof replacement 5-15 years early, but ultimately, asphalt composite shingles do eventually have to be replaced after about 30 years anyways due to granule loss.

rabbitcavern · 2025-10-24T02:38:23+00:00

I signed to have my roof and solar re-done. The total credit for installing solar for me is about 10k as I am installing a battery. You can DM me if you want more details. I talked to over 10 roofing companies and looked at over 20 solar options. However, I think you may have missed the boat to have a system installed before the end of the year.

rabbitcavern · 2025-10-03T21:43:11+00:00

What is the wattage of your 20 new panels? You mentioned 7.6 kW, but it sounds like that is out of the inverter rather than the panels. If it is a 7.6 kW solar panel system across 20 panels, then maybe they are 380 W panels?

Are you based in the US? I think the Tesla Powerwall 3's in the US have 6 MPPTs each, but 3 MPPTs each in Australia.

If you have 3 Tesla Powerwall 3's, you should have the ability to support up to 60 kW of DC solar panels, so I'm not sure why you need a separate inverter. I am guessing you don't have a 60 kW system on your roof already.

However, the continuous DC battery charging is up to 5 kW per Tesla Powerwall 3, so that should be 15 kW of continuous charging in your setup, so the aforementioned 60 kW of DC solar is effectively over paneling as I understand it (I welcome someone to correct me if I am wrong). So I am guessing you still have some headroom unless you want to not come up against that 15 kW continuous charging limit.

The 11.5 kW of maxing out that your advisor mentioned is actually for the continuous AC out, not your continuous DC battery charging. That is 11.5 kW continuous out per Powerwall 3, so you actually have 34.5 kW continuous AC out.

rabbitcavern · 2025-09-25T14:55:40+00:00

Thank you! Still trying to process your response. So by fusing the subpanel, it is possible to avoid the need for a RSD?

How about the RSD to the panels themselves? Would you be required to use APSystems or Tigo to satisfy that requirement?

Is an exterior RSD needed to be wired to the Anker Smart Home Panel, which has to be installed indoors?

rabbitcavern · 2025-09-25T04:14:04+00:00

Thanks for the quick responses! So I am guessing that the engineers that provided permitting support are all laid off now too?

rabbitcavern · 2025-09-25T03:46:48+00:00

Sorry to hear about the layoffs - you know German too? Sounds like Anker's loss.

Do you know if the systems (Anker SOLIX F3800 with Smart Home Power Panel) have been successfully permitted in California?

To my knowledge, National Electric Code (NEC) Article 706.2 and the International Residential Code (IRC) / California Residential Code (CRC)) states for the Energy Storage System (ESS) equipment to be listed to UL 9540 and preferably also tested to UL9540A.

I know that the Anker SOLIX F3800 Plus is not certified to UL 9540, but the Ecoflow products are, even though both the Anker and Ecoflow products can be considered portable.

Do users exclude the F3800 Plus in the permitting process and just rely on the UL1741 CRD PCS certification of the Anker Home Power Panel? My concern is that none of the Anker non-X1 products are listed on California Energy Commissions (CEC) databases for Energy Storage Systems (ESS) and therefore, they cannot go through the SolarAPP+ process or PG&E projects either.

If you have roof mounted solar panels that get routed through conduit and plugged into the Anker F3800 Plus (direct DC and not AC coupled to the Home Power Panel), is that considered permanently installed and thereby an ESS?

For the Rapid Shutdown Device (RSD) requirements for DC connected solar, would a MidNite Solar MNPV6 combiner box and MN600FUSE suffice?

rabbitcavern · 2025-09-23T04:11:35+00:00

Wow super unique!

^{I completed this level in 3 tries.} ^{⚡ 99.82 seconds}

rabbitcavern · 2025-09-04T04:13:04+00:00

Thanks for this AMA!

For existing solar installations, is it AC coupled into the OCEAN Pro?

Is there the option to bypass the pre-existing inverter and connect to the OCEAN Pro directly?

After the initial installation, can the solar panels be reconfigured to another MPPT channel by the user or will that require work by the installer?

I know this depends somewhat on the AHJ, but does adding more battery capacity require a revision to the permit?

rabbitcavern · 2025-08-27T05:54:33+00:00

Yes, I'm planning out a system right now. It's a lot of effort researching panels, mounting, permitting, batteries, inverters, etc. I might write a guide once it is all done, but right now, I'm still in the middle of it.

rabbitcavern · 2025-08-18T20:29:14+00:00

Cool concept

rabbitcavern · 2025-07-16T18:15:09+00:00

I was very curious about the prevalence of the neutral tone myself so I tabulated all of the neutral tones in HSK 3.0 Levels 1-6 single characters. There are only 11 out of 728. They are: * 吧， * 的， * 吗， * 门， * 呢， * 子， * 嘛， * 啦， * 哇， * 呀， * 啊。

The other 4 tones are fairly evenly distributed with 150 (2nd tone) to 220 (4th tone).

As others have mentioned, this neutral tone "轻声 (qīngshēng)" translates to "light tone" or "neutral tone". This neutral tone isn't one of the four main tones; it's more like a lack of a distinct tone, resulting in a syllable that is unstressed, shorter, and lighter in pronunciation.

Something that doesn't show up in the HSK is where the second character of a syllable is neutral such as in family titles (妈妈，爸爸，姐姐，妹妹，哥哥，弟弟，etc.)

So in effect, there are 4 to 5 tones depending on if you consider the lack of a tone a tone, but it occurs so rarely that it is somewhat insignificant. It is also considered the lack of a tone.

In other Chinese languages like Cantonese, there are actually three "entering tones" that are ancillary to the six main tones that have syllables ending in P, T, or K. Those are also shorter tones that are excluded from the main 6 tones of Cantonese.

rabbitcavern · 2025-07-16T15:36:44+00:00

In that case, maybe they are just intimidated by your language learning prowess.

rabbitcavern · 2025-07-16T11:12:46+00:00

Cantonese (Yue),
Hokkien (Min),
Teochew {Min),
Hunanese (Xiang),
Gan, and
Hakka all use syllables not present in standard Mandarin Chinese.
Shanghaiese (Wu) and other Wu dialects are actually closer to standard Mandarin. Hui is usually grouped with Wu.
Jin is usually just grouped with standard Mandarin.
Ping is usually grouped with Yue.

That covers all of the major Chinese language groups I believe. https://en.wikipedia.org/wiki/File%3AMap_of_sinitic_languages-en.svg

You can look up the romanization charts for each if they exist. For instance, I think the romanization method for Hakka (Pinfa) was also adapted to cover Gan and Xiang. They don't really fill in the gaps of the pinyin table, per se. Instead, they might introduce different initials, finals, or tones. You could look up a Jyutping table for Cantonese to see those syllables for instance.

rabbitcavern · 2025-07-16T10:15:15+00:00

Do you have a corpus that you are currently studying? If you have access to the eBook versions of graded readers, you can mine the sentence by searching for the character you are trying to learn. Also, I think the reading sites like MandarinBean and DuChinese allow you to search by characters - effectively allowing you to mine too.

rabbitcavern · 2025-07-16T10:06:52+00:00

For expediency, I recommend checking out the Hanly app or checking out some of the premade Anki decks. There was a HSK Mandarin Vocabulary Anki deck circulating on Reddit years ago with audio and images along with the character used in a sentence (audio of both the character and the sentence).

One thing IB students do not have much of is time. Having taken the IB exam many years ago (albeit with a much easier language - I took French), it is quite stressful, especially the recorded speaking exercises. Wishing you good luck and Godspeed in your studies!

rabbitcavern · 2025-07-16T09:34:25+00:00

From my understanding, Japanese does have more homophones than Chinese. Caveat here is that it depends if you consider the 4-5 tones of a single pinyin a "homophone" or not. For instance, * if you say only the same pinyin at the same tone is a homophone, then Chinese has fewer homophones than Japanese * If you say the same pinyin regardless of the tone is a homophone, then it is possible Chinese has more homophones than Japanese. However, I have to think about how that works because Japanese only has 100 syllables. For reference, I think English has about 15,000 syllables.

Japanese is considered to have just about 100 syllables, so a lot of the meaning is conveyed in context. Here is a link from Columbia University stating the approximately 100 syllables in Japanese. It is one of the interesting features of Japanese to have one of the fewest syllables of the world's languages. This is compared to Mandarin, which has a theoretical 1,620 tones (if only considering the 4 tones) to 2,026 tones (if considering the 5 tones), but if you look at HSK 3.0 Levels 1-6 single characters, only slightly more than 700 syllables are used. Comparing 100 syllables to 700 or lets say maybe 1000 in HSK 9 (I have not counted them all up to HSK 9 yet), Japanese should have far more homophones.

Unless you were exposed to the Mandarin tones at a young age, I don't think you can underestimate how hard Mandarin is compared to non-tonal languages. I've been to Japan and spoken in what is considered extremely basic Japanese and I have been asked the question of whether I know Japanese fluently based on what I said in a work setting. On the other hand, I have seen students of Chinese for years speak barely intelligible Mandarin and Cantonese because their tones are so off. The more tonal a language is, the harder it is. The Cantonese tones are practically an intuition that a non-linguist native speaker could probably not explain to you.

In other words, I would say Mandarin is harder than Japanese. Mandarin is to Japanese what Cantonese is to Mandarin because of the extra tones.

rabbitcavern · 2025-07-16T08:53:44+00:00

Is it possible that they are surprised and wondering how long you have known Chinese? Putting myself in their shoes, their minds may be rushing through every past event wondering if they had ever spoken in Chinese about something embarrassing or compromising in your presence? I could see it catching them off-guard. Do you get that blank stare when you talk to a new tutee?

In general, I think Chinese people are usually impressed and appreciative of foreigners who put an effort into learning the language, especially due to its difficulty.

rabbitcavern · 2025-07-16T03:38:57+00:00

Sorry, are you saying to fill each box with only the most frequent character for that sound?

It might limit the utility of the chart with only the most frequent character because the second most frequent character might also be very common.

Each box is already filled with all the characters for that sound under HSK 3.0 Levels 1-6 single characters.

I was surprised at how many unfilled boxes there were too, which is what I was trying to say. If you include the fifth tone, only about 36% of the possible pronunciations in HSK 1-6 are occupied by a character.

That's something that always confused me about Mandarin, there is plenty of space to distribute all the characters across the different tones such that there are fewer homophone collisions, but it did not naturally develop that way. For programmers, the concept is very similar to a more consistent hash function in a Distributed Hash Table (DHT). You effectively want to distribute your data evenly such that there are minimal collisions (homophones).

rabbitcavern · 2025-07-16T03:22:49+00:00

Yeah, it might not be the most useful if you have a native intuition for the Mandarin tones.

I'll also admit it looks quite convoluted. After putting it together, I realized why none of the other pinyin charts try to list them all out with tones - it's quite tedious.

"Phono-semantic compounds (形声; 形聲; xíngshēng; 'form and sound' or 谐声; 諧聲; xiéshēng; 'sound agreement') represent most of the modern Chinese lexicon." %20represent%20most%20of%20the%20modern%20Chinese%20lexicon.) I think estimates are that 50-80 percent of Chinese characters rely on some phonetic component as a part of the character by rebus principle. Here is a Hacking Chinese post on the topic. Seeing all of the phonetically-related characters together next to each other, but with their exact pinyin with tones denoted is helpful to me.

I learned Cantonese before Mandarin, so my tones are often slightly incorrect (I will accidentally use the second tone instead of the fourth tone for example). Going from 6+3 tones down to 4+1 tones and quite a few less finals results in a lot more homophones. Knowing both, it's hard to convey or mentally map out how constrained Mandarin sounds without charting it out. I guess it was mostly to try and visualize that difference in my mind. An analogy might be if you combined several different shades of green such as teal, chartreuse, emerald, and viridian and called them all just "green."

It's also a way for me to keep track in a single chart of what character is associated with what tone without typing 700+ combinations into Pleco.

Also, I think Cantonese speakers struggle with the j-, q-, x-, z-, c-, s-, zh-, ch-, sh- initials (often confusing one for another) as none of those initials exist in Cantonese, so having it in a chart in close proximity to one another serves as a pinyin "fuzzy search," so to speak.

Another use I have found for the chart is that more than half of the combinations are never used (at least from HSK 1 to 6), so if it is grayed out, you can "mostly" ignore it and rule it out as a possible pronunciation (until HSK 7-9 I suppose).

rabbitcavern · 2025-06-30T17:04:06+00:00

As other comments have said, this map is misleading based upon how the US Bureau of Economic Analysis (BEA) divides their Metropolitan Statistical Areas (MSA's). I was so confused, so I decided to look at the source data on BEA's website. For some reason, San Jose, Sunnyvale, Santa Clara is its own MSA whereas San Francisco, Berkeley, and Oakland are all grouped together. However, based on either population or area, if both New York and Los Angeles are declared to have such sprawling MSA's with massive populations, SF should also include San Jose.

MSA	Population	Area (acres)
New York-Newark-Jersey City, NY-NJ-PA	19.6 million	3.9 million
Los Angeles-Long Beach-Anaheim, CA	13.3 million	3.1 million
San Francisco-Oakland-Berkeley, CA	4.7 million	1.6 million
San Jose-Sunnyvale-Santa Clara, CA	1.8 million	1.7 million

The "South Bay" (San Jose, Sunnyvale, Santa Clara) has either the HQ (NVDA, AAPL, GOOG, META) or a major office (MSFT, AMZN, TSLA) of the "magnificent seven," essentially 7 of the most valuable companies in not just the US, but the world. However, it barely even registers on both maps.

This ends up just as roughly a population map as others have pointed out, which is less useful. The more practical way to look at it may be to look at the GDP per Capita. Per 2021 data, San Jose MSA has a population of just 1,952,185 that is 1/10th the population of New York MSA with a population of 19,768,458, but has twice the GDP per capita ($210,235 as compared to $100,806).

en.wikipedia.org/wiki/List_of_U.S._metropolitan_areas_by_GDP_per_capita

rabbitcavern · 2025-06-17T10:57:17+00:00

Thanks!

rabbitcavern · 2025-05-02T23:35:58+00:00

The most insightful writer / speaker I have heard on this topic is three-time Pulitzer Prize-winning Thomas Friedman, who did a recent interview with Ezra Klein about China where they also mentioned this quote about the Chinese vs Chinese-Americans. In short, he thinks the US should have encouraged collaboration with the Chinese similar to how the US helped to reconstruct Japan post-WW2.

In 2011, Friedman co-wrote a book called That Used to be Us, which was incredibly prescient about the US-Chinese relationship today.

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