シャドーイング練習: The Hidden Problem With Home Batteries - 動画で英語スピーキングを学ぶ
レッスンを作成中...
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This is my electric bill from January.
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I have solar on the roof and 20 kWh of battery bolted to my garage wall.
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Even with all of that, the Eversource bill came out to $336.
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And Banked Sunshine from last summer paid $166 of it.
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Then the credit bank hit zero and my next bill came entirely out of my pocket.
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So here's the part that took me two years and a spreadsheet to work out.
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Every dollar of that rescue came from the panels on my roof, and the battery didn't help.
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12 months of my own utility bills
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and ran them against 12 months of data from the panel that meters every single circuit in my house.
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Then I ran those same 12 months again with the battery deleted.
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My battery costs me about $270 a year in electricity and has never saved me a dollar.
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Not once.
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And I'd buy it all again tomorrow.
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I know exactly how that sounds, but stick with me here, because by the end of this you'll know why
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and then you'll be able to decide whether my reasons align with your reasons.
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There's also something I realized I got wrong about my electric bill that I stated in a previous video two years ago.
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So what did I learn about home batteries after living with them across two homes over six years?
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And are they worth it?
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I'm Matt Farrell.
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Welcome to Undecided.
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This video is brought to you by Surfshark.
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A quick bit of history because it matters more than it looks like it does.
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In my old house, I had one Tesla Powerwall.
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Tesla's referral program gave me the hardware for free, but I paid for the installation costs.
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previous video.
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That meant I had to estimate the total overall costs whenever
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I talked about the calculation of payback numbers for my previous house.
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It was also a ballpark estimate because of the referral program.
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But this time I paid for the whole thing.
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Four Enphase IQ5P batteries, which means 20 kWh of storage and 15.4 kW of output. $33,407 all in before any rebates.
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The federal tax credit took 30% off and Massachusetts kicked in $1,000, so the net cost was $22,385.
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That's $1,119 for every single kilowatt hour hanging on that wall.
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I financed it with a MassSave 0% heat loan.
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It's a great program that Massachusetts runs to offer low
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or no interest loans for home energy upgrades on things like HVAC heat pumps to home batteries.
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Again, nobody sent me these batteries, so there's no sponsor.
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That's my money on the wall.
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And here's what I thought I was buying.
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Keeping those electrons generated on my roof, in my house, to help keep my electric bill low.
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Also the ability to shrug at a power outage.
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There's more to that, but only one of those turned out to be real.
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Before we get into the money, return on investment, and all the other reasons you might want to get a home battery, here's what this thing does on an ordinary Tuesday.
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Taking the last 18 months of data off my Span Smart Electric panel gives some really interesting insights.
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On a median day, the battery discharges 11.3 kWh.
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Over the last complete year, it moved 3,673 kWh into the house.
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And here's the key thing to keep in mind.
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The season decides everything.
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In January, my solar panels generate about 20 kWh a day, while my house eats 52.
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And yes, that's a lot, but remember that my house is all electric with an EV, heat pumps for heating and hot water.
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Like everything.
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There's no excess electricity generation to store, so the battery only moves about 6 kilowatt hours or so a day.
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However, in July I make 61 kilowatt hours a day and use 58, which results in the battery moving about 14 kilowatt hours.
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One quick clarification on my setup is that I keep my battery system set to 20% battery reserve, which means my total usable capacity isn't 20 kilowatt hours, it's more like 16.
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Now let's do some division, because who doesn't like some math?
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3,673 kilowatt hours a year over 16 usable kilowatt hours is 230 full battery cycles a year.
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My warranty covers 6,000 cycles or 15 years, but at my rate, I won't hit 6,000 cycles until year 26.
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It's kind of like a car warranty.
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Your car may come with a 150,000 mile warranty, but if you only drive 4,000 miles a year, the warranty will expire by its time limit first.
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I'm like that little old lady who only drives to church and back once a week.
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So this battery is going to age out long before it wears out.
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I wish I could say the same thing about my knees.
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That sounds like good news, right?
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It's actually the whole monetary problem because every dollar I spent has to spread across a very small pile of kilowatt hours.
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And that pile is smaller than I told you it was.
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Two years ago I sat here and explained how my electric bill works and I got part of it wrong.
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I didn't find out until I pulled the last 12 months of statements for researching this video.
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But hang tight because I'll show you the exact line item that proves it.
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But the reason I got it wrong was that something changed quietly and nobody told me.
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Your personal information works the same way.
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And that's where today's sponsor, Surfshark, comes in.
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I spend a lot of time thinking about protecting my home from the stuff I can't control.
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Power outages, price spikes, the grid having a bad day, and I got reminded the digital side needs the same attention recently.
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There was a massive BrightSpeed data breach that leaked personal info on more than 1 million customers.
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Things like names, emails, phone numbers and more.
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It's It's really cool.
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Go to surfshark.com slash undecided or use code undecided at checkout.
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Surfshark offers a 30-day money back guarantee, so there's no risk to try it out for yourself.
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I've been using Surfshark for years and I love it.
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Don't miss out on this great deal.
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The link's in the description below and thanks to Surfshark and to all of you for supporting the channel.
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OK, let's pull up my bill.
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Let's go slowly here.
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More for me than for you.
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My meter keeps a tab.
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One counter for kWh coming in from the grid and one for kWh going out.
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Eversource subtracts one from the other once a month and everything on my bill is computed on the difference.
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The bill makes it pretty clear.
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Consumption of 1,181 kWh, minus 143 for generation, nets 1,038.
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Then watch what happens to that 1,038 kWh.
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Both the supply and delivery chargers are computed on 1,038.
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The kWh I exported canceled the kWh I imported, delivery charge included.
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In Massachusetts that means about $0.32 of value for each one.
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That's a real one for one trade.
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And it's always worked that way here.
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So what does the battery have to do with any of that?
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Take July of last year, a month where I sent out far more than I took in.
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With the battery I imported 853 kWh and exported 1,420.
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Without it, I'd have imported 1,361kWh and exported 1,999kWh.
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The battery cut both sides by roughly the same amount.
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So my net barely budged and I came out $18 worse off.
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Now let's look at the month where I owed money.
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December of 2024.
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With the battery I paid $231.07, which is exactly what Eversource billed me.
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Without it, it would have cost $192.62, which means the battery cost me $38.
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This type of thing is happening every single month.
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Across the last 12 months, the battery cost me $207.
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The reason is almost embarrassingly simple.
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With every kWh I run through the battery, I lose about 16% as heat.
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714 kWh a year, gone.
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The cars in my garage might be slightly cozier because of that, but my wallet is not.
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Under a flat electricity rate like mine, along with basically 1 to 1 net metering, the grid is a better battery than my battery.
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It's virtually 100% efficient.
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But two years ago, I told you Massachusetts credits your exports at the generation rate only.
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So you eat the delivery charge on everything you send back.
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And I said the battery helps you dodge that.
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Many states in the country operate that way, so in those locations, that's 100% true.
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But my specific case, only half of what I said was true.
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In early 2024, my credit really was about 54% of retail, which certainly looks generation only.
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In February of 2025 it jumped to 85% and today it matches supply plus distribution plus transmission almost to the penny.
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My export terms improved by more than half and nobody told me.
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Not sure why.
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I only found it because I keep a spreadsheet.
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In case you couldn't tell, kind of a nerd.
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But the conclusion I drew was wrong back then.
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There is a haircut happening on the net metering credit for me.
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It's about 4.8 cents and it only touches the surplus
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that spills into the credit amount that builds up over the summer months.
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My battery couldn't capture it either way.
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And here's the number that nobody who's selling you a battery will put on a slide.
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So let's put a price tag on a stored kWh.
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Start with the net cost of $22,385.
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Spread it out over everything the battery will deliver in 20 years at my usage level, which is about 64,000 kWh.
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That number assumes the battery loses about 1.5% of capacity every single year, which is what the published data on this battery chemistry actually shows.
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That's $0.35 a kWh just for the hardware.
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This is not accounting for my solar panel setup, just the battery by itself.
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But when we do account for the solar I'm generating, we have to account for the cost of charging the battery.
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Every excess kWh I put into the battery is one I could have sold back to the grid for $0.28.
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Because I lose 16% in round trip efficiency, that works out to another $0.33 for every kilowatt hour I get back out. $0.68.
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That's what one kilowatt hour of my battery costs me.
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The one it replaces is worth $0.28 and I can buy one off the grid for $0.32.
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I'm paying more than double the grid price to store electricity I already own, and longer battery life doesn't rescue it.
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Stretch it to 25 years and it only falls to $0.62, because the cost of filling it never changes.
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And before you jump into the comments and try to dunk on home batteries in general, or especially on my setup, there is money in this system and it comes from exactly one place.
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My utility rents my battery.
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It's called Connected Solutions.
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Every summer between June and September, there's 40 or so afternoons that Eversource sends a signal to my battery to dump its power back into the grid.
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The sessions last for about 2-3 hours right around the 5pm crunch.
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Enphase pays $275 per average kilowatt delivered and passes 100% of that money from my utility to me.
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Some companies don't because they take a cut.
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But how's it work out?
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In 2024 I earned $1,881.38.
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In 2025 I earned $1,634.35.
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So why was one year 13% less?
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Both years my battery dumped essentially the same energy per event, about 14.5 kWh.
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What changed is how long the utility stretched it out.
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The program pays on average kW, not kWh.
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Basically, you get paid for how fast you can empty your bucket instead of how much water is in it.
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Same energy over 2 hours scores 7.3 kW.
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Over 3 hours, 4.8 kW.
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In 2024, 82% of my events were 2 hours.
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In 2025, only 55%.
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Same battery, same job, but a third less money.
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And I have zero say in it.
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Which brings us to the real question, does a home battery make financial sense?
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If you take the $207 a year my battery costs to run out of the Connected Solutions income, I'm netting about $1,550 a year if I average the first two two years.
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My enrollment runs for five years, but my understanding is that I might be able to re-enroll.
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If participation does end after five years, this battery will only recover about 20% of its cost over 25 years, and then it bleeds $200 a year forever.
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If it renews beyond the five-year period, it might pay for itself in year 15.
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The whole answer is kind of fuzzy on what's going to happen down the road.
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So when looking at the finances and ROI of a home battery, the math is saying no, it's not worth it.
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So here's the question I've been dodging for the past 10 minutes.
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Why don't I regret this?
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Why on earth would I do it all over again?
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That's because this isn't an investment decision.
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I'm not deciding what stocks to buy or where to invest my money for a financial return.
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Ask yourself, what does a battery do?
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What's its function and purpose for what you want it for?
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Do you buy a lawnmower because it's an investment or because it serves a task?
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For instance, look at my emergency backup history.
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For the past 26 months, I've had 10 outages for a total of 51 minutes.
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Out of those, the longest one lasted 11 minutes.
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On his face, it sounds like I'm spending over $22,000 for 51 minutes of backup is an insane decision.
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But here's what actually happened during those 10 outages.
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Nothing.
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We didn't notice.
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There were times we were running on backup and had no clue.
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No flicker, no beeping, no clocks blinking at us the next morning.
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I found out afterward from a log or phone notification that I missed.
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And that's the thing the spreadsheet can't see.
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Every number in this video is a money calculation, and money is not why most people buy a battery.
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So let's talk about my actual reasons for wanting a home battery.
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Contradictions included because I think the contradictions are the interesting part.
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I wanted energy independence.
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Meanwhile my utility takes the wheel 40 or so afternoons during the summer, and that's the only part of this that pays.
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My money and motivation are pointing in opposite directions.
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I wanted to use my own clean solar power power being generated on my roof.
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And To do it, I throw away 714 kWh a year as heat.
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Storing my own sunshine is less efficient than shipping it to the grid and buying it back.
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But I wanted resilience.
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I didn't size it for the worst case scenario.
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20 kWh runs my whole house about 8 hours in January, if I didn't do any kind of curtailment.
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A genuine multi-day nor'easter needs 3 or 4 times that.
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I made a rational call about how much backup I'd most likely need.
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Going off-grid was never my motivation.
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If I shut things down to just the critical loads like the fridge, the HVAC, a few lights, and with any January sun at all, I can run it indefinitely.
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That's the span panel helping me to shape my energy usage during an outage.
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Most people just install a hard-wired critical loads panel to do the same thing, but I'm able to adjust my critical loads in software.
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I can be more flexible with it depending on what's actually happening.
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The last rationale for getting a home battery tends to trip up everybody.
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Independence and resilience are two different things.
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Independence means leaving the grid.
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Resilience means the grid can stay.
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It just stops mattering when it fails.
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And I want the second one.
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Those two get mashed together constantly and they buy you completely different systems.
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EnergySage asked homeowners and installers the same question in the same survey.
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67% of installers said people buy batteries for resilience, only 11% for savings. To homeowners?
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30% said rate savings.
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A lot of people are being sold one story while telling themselves another and nobody's numbers get checked.
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And there's one benefit that the whole spreadsheet misses.
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When my battery discharges at 5pm on a 90 degree Fahrenheit day, it's shoving aside the dirtiest power on the grid.
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Peaker plants are what's running at that hour.
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Last year my battery pushed 611 kWh into the grid across 43 events.
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Every one of them timed to the filthiest moment of the day.
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My solar can't do that on its own.
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So here's where I land.
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I can't tell you this pays for itself, because in my situation, it doesn't.
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What I can tell you is what $22,000 actually bought for a nerdy homeowner in Massachusetts.
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It bought 10 power outages that I slept or worked through.
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It bought about $1,550 a year for as long as Eversource keeps renting it.
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It bought a house that holds its fridge
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and HVAC through a storm as long as the sun shows up from now and then.
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And it bought me the ability to stop thinking about winter nor'easters, which… knock on wood, hasn't impacted me in this house yet.
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It definitely did in my previous house.
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I've experienced much longer outages and it's not fun.
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Which is why I'd much rather be prepared with my energy storage backup.
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It costs me $207 a year in electricity and it will very likely never pay itself back.
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But it depends on where you live and how your electricity rates are structured.
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And this was my favorite part of digging into this topic.
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While I was pulling bills for this video, I found this.
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Eversource swapped my meter in February.
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Western Massachusetts is first in line for their smart meter rollout.
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A million and a half of them will be installed by the end of 2027.
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And the entire point of that program is time of use rates.
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Now, time of use would flip my energy math from negative $200 a year to somewhere between $170 and $800 positive,
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depending on how Massachusetts structures the rates.
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It definitely helps, but it still doesn't make it a crystal clear investment.
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The program renting my battery still does that.
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But here's the part I'm fixated on.
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A better peak rate wouldn't help my battery.
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But my utility paying me less for excess solar power I send back would.
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Right now, the grid is a perfect virtual battery for anyone that lives in my area with solar.
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It's free and never loses a thing.
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That's exactly why my battery can't win.
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The policy change I'd normally be complaining about is the one
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that would actually vindicate the purchase and honestly be more fair to all the non-solar homeowners and renters in my area.
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And yes, I'm advocating for not having a 1 to 1 net metering.
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I think it's more fair to have generation only credits for solar homeowners.
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Come at me in the comments if you disagree.
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And if you've got a battery of your own, I'd genuinely like to see your numbers and hear about your motivations on getting one.
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And for those of you that don't have home batteries, do you want them?
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Do they make sense in your area?
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Jump in the comments and let me know.
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You can also check Check out extended cuts of many of my videos over on Patreon.
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If human-written and researched videos matter to you, Patreon support helps a ton.
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The link's in the description if you'd like to join, but just watching, subscribing, and turning on notifications is awesome.
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Check out my follow-up podcast, Still to be Determined, where we'll keep this conversation going.
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Keep your mind open, stay curious, and I'll see you in the next one.
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このレッスンの語彙とスピーキングのポイント
このB2レベルのスピーキングレッスンは、動画「The Hidden Problem With Home Batteries」を教材にしています。 繰り返し出てくる語は次のとおりです：battery, kwh, hour, grid, cost。 この動画には、シャドーイング用の文が273文、単語が3307語あります。 音声の長さは17:54です。 話す速さは速く、1分あたり約185語です。音のつながりや弱く発音される音が多くなります。 英語の頻出3,000語に含まれる単語は81%だけなので、語彙は難しめです。
この動画の重要語彙
動画の中で特に難しい単語15語を、発音と意味つきで紹介します。
| 単語 | 発音 | 意味 |
|---|---|---|
| grid 名詞 | /ɡɹɪd/ | 格子, グリッド |
| kilowatt 名詞 | /ˈkɪ.ləˌwɒt/ | キロワット |
| homeowner 名詞 | 家持ち | |
| spreadsheet 名詞 | /ˈspɹɛd.ʃit/ | 表計算ソフト, スプレッドシート |
| meter 名詞 | /ˈmitəɹ/ | メーター, 計量器 |
| metre 名詞 | /ˈmiːtəɹ/ | メートル, ㍍ |
| import 名詞 | /ˈɪm.pɔɹt/ | 輸入品 |
| mathematics 名詞 | /mæθ(.ə)ˈmæt.ɪks/ | 数学 |
| compute 動詞 | /kəmˈpjuːt/ | 計算する |
| contradiction 名詞 | /ˌkɑːntɹəˈdɪkʃən/ | 反論, 反駁 |
| installer 名詞 | インストーラー, インストーラ | |
| calculation 名詞 | /ˌkælkjuˈleɪʃn̩/ | 計算 |
| notification 名詞 | /ˌnoʊtɪfɪˈkeɪʃn̩/ | 通知 |
| discharge 動詞 | /dɪsˈtʃɑɹdʒ/ | 全うする |
| sponsor 名詞 | /ˈspɒn.səː/ | スポンサー |
動画に出てくる句動詞
| 単語 | 発音 | 意味 |
|---|---|---|
| check out 動詞 | 試験する, 検査する | |
| find out 動詞 | 見出す, 調べる | |
| come out 動詞 | /ˌkʌm ˈaʊt/ | 出る |
| go out 動詞 | 出る | |
| pull up 動詞 | /ˌpʊl ˈʌp/ | 引き上げる |
| take off 動詞 | 脱ぐ | |
| throw away 動詞 | 棄てる, 捨てる | |
| wear out 動詞 | 擦り減らす |
繰り返し練習したい文
動画に出てくる短く完結した文です。日常会話でそのまま使えます。
- That's my money on the wall.
- In case you couldn't tell, kind of a nerd.
- Why don't I regret this?
- What's its function and purpose for what you want it for?
- Do they make sense in your area?
この動画の文法
話し手がよく使っている文型を、動画の実際の表現とともに紹介します。
| 文型 | 動画での表現 |
|---|---|
| 現在完了進行形 have/has been + -ing — 以前に始まり今も続いている動作 | I've been using · I've been dodging |
| 受動態 be + 過去分詞 — 誰がするかより、何が起きるかに焦点を当てる | is brought · is computed · are computed |
| 現在完了形 have/has + 過去分詞 — 過去の出来事が今も関係している | has never saved · have imported · hasn't impacted |
| 関係詞節 who / which + 節 — 人や物について情報を加える | batteries, which means · reserve, which means · level, which is |
注意したい発音
話し手はI'm, I'd, can'tなど、短縮形や弱形を52回使っています。聞こえたとおりの短い形で発音しましょう。
- 「sh」と「zh」の音: spreadsheet /ˈspɹɛd.ʃit/, contradiction /ˌkɑːntɹəˈdɪkʃən/, calculation /ˌkælkjuˈleɪʃn̩/, notification /ˌnoʊtɪfɪˈkeɪʃn̩/, sunshine /ˈsʌnʃaɪn/
- 長い単語（アクセントの位置に注意）: resilience /ɹɪˈzɪl.ɪ.əns/, undecided /ˌʌndɪˈsaɪ̯.dɪd/, mathematics /mæθ(.ə)ˈmæt.ɪks/, contradiction /ˌkɑːntɹəˈdɪkʃən/, notification /ˌnoʊtɪfɪˈkeɪʃn̩/
日本語話者が苦手な音：
- /r/ と /l/ の区別 — /l/ は舌先を歯茎につけ、/r/ はどこにもつけない: resilience /ɹɪˈzɪl.ɪ.əns/, referral /ɹɪˈfɜː.ɹəl/, rationale /ˌɹæʃ.əˈnæl/, clarification /ˌklæɹɪfɪˈkeɪʃən/, enrollment /ənˈɹəʊl.mənt/
- /f/ — 「フ」ではなく、上の歯と下唇で出す: referral /ɹɪˈfɜː.ɹəl/, notification /ˌnoʊtɪfɪˈkeɪʃn̩/, clarification /ˌklæɹɪfɪˈkeɪʃən/, indefinitely /ɪnˈdɛfɪnɪtli/, fuzzy /ˈfʌzi/
- 子音の連続 — 間に母音を入れない: grid /ɡɹɪd/, spreadsheet /ˈspɹɛd.ʃit/, resilience /ɹɪˈzɪl.ɪ.əns/, import /ˈɪm.pɔɹt/, mathematics /mæθ(.ə)ˈmæt.ɪks/
この動画での練習方法
- まず声を出さずに動画を最後まで聞き、知らない単語をメモします。
- まず0.75倍速で一文ずつシャドーイングし、慣れてきたら通常の速度に戻します。
- 自分の声を録音して元の音声と比べます。grid, kilowatt, homeownerなどの単語に特に注意しましょう。
シャドーイングとは？英語上達に効果的な理由
シャドーイング（Shadowing）は、もともとプロの通訳者養成プログラムで開発された言語学習法で、多言語習得者として知られるDr. Alexander Arguelles によって広く普及されました。方法はシンプルですが非常に効果的：ネイティブスピーカーの英語を聞きながら、1〜2秒の遅延で声に出してすぐに繰り返す——まるで「影（shadow）」のように話者を追いかけます。文法ドリルや受動的なリスニングと異なり、シャドーイングは脳と口の筋肉が同時にリアルタイムで英語を処理・再現することを強制します。研究により、発音精度、抑揚、リズム、連音、リスニング力、そして会話の流暢さが大幅に向上することが確認されています。IELTSスピーキング対策や自然な英語コミュニケーションを目指す方に特におすすめです。