Pratique du Shadowing: The Hidden Problem With Home Batteries - Apprendre l'anglais à l'oral avec la vidéo
Création de la leçon...
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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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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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Things like names, emails, phone numbers and more.
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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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Vocabulaire et conseils d’expression pour cette leçon
Cette leçon d’expression orale de niveau B2 s’appuie sur la vidéo « The Hidden Problem With Home Batteries ». Les mots qui reviennent le plus souvent : battery, kwh, hour, grid, cost. Cette vidéo contient 273 phrases et 3307 mots à répéter en shadowing. La partie parlée dure 17:54. Le locuteur parle vite, environ 185 mots par minute : attendez-vous à des liaisons et à des sons réduits. Seuls 81 % des mots font partie des 3 000 mots les plus courants en anglais, le vocabulaire est donc exigeant.
Vocabulaire clé de cette vidéo
Les 15 mots les plus avancés de la vidéo, avec leur prononciation et leur sens :
| Mot | Prononciation | Sens |
|---|---|---|
| grid nom | /ɡɹɪd/ | grille |
| kilowatt nom | /ˈkɪ.ləˌwɒt/ | kilowatt |
| outage nom | /ˈaʊ.tɪd͡ʒ/ | panne, interruption |
| spreadsheet nom | /ˈspɹɛd.ʃit/ | tableur, chiffrier |
| resilience nom | /ɹɪˈzɪl.ɪ.əns/ | résilience |
| meter nom | /ˈmitəɹ/ | mètre, compteur |
| undecided adjectif | /ˌʌndɪˈsaɪ̯.dɪd/ | indécis, non décidé |
| metre nom | /ˈmiːtəɹ/ | mètre |
| import nom | /ˈɪm.pɔɹt/ | importation |
| mathematics nom | /mæθ(.ə)ˈmæt.ɪks/ | mathématiques |
| compute verbe | /kəmˈpjuːt/ | computer, calculer |
| contradiction nom | /ˌkɑːntɹəˈdɪkʃən/ | contradiction |
| installer nom | installateur, installatrice | |
| usable adjectif | /ˈjuː.zə.bəl/ | utilisable |
| calculation nom | /ˌkælkjuˈleɪʃn̩/ | calcul |
Les verbes à particule que vous entendrez
| Mot | Prononciation | Sens |
|---|---|---|
| check out verbe | mater, regarder | |
| find out verbe | découvrir, savoir | |
| work out verbe | /ˌwɝk ˈaʊt/ | calculer |
| come out verbe | /ˌkʌm ˈaʊt/ | sortir |
| go off verbe | exploser | |
| go out verbe | sortir | |
| pull up verbe | /ˌpʊl ˈʌp/ | soulever |
| take off verbe | enlever, ôter |
Des phrases à répéter
Des phrases courtes et complètes de la vidéo, à réutiliser dans la conversation de tous les jours :
- 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?
La grammaire de cette vidéo
Les structures que le locuteur utilise le plus, avec les mots exacts de la vidéo :
| Structure | Dans la vidéo |
|---|---|
| Present perfect continu have/has been + -ing — une action commencée avant et toujours en cours | I've been using · I've been dodging |
| Voix passive be + participe passé — l’accent est mis sur ce qui arrive, pas sur qui le fait | is brought · is computed · are computed |
| Present perfect have/has + participe passé — une action passée qui compte encore maintenant | has never saved · have imported · hasn't impacted |
| Propositions relatives who / which + proposition — une précision sur une personne ou une chose | batteries, which means · reserve, which means · level, which is |
Prononciation à surveiller
Le locuteur utilise 52 contractions et formes réduites, comme I'm, I'd, can't. Prononcez-les sous leur forme courte, telles que vous les entendez.
- Les sons « sh » et « zh »: spreadsheet /ˈspɹɛd.ʃit/, contradiction /ˌkɑːntɹəˈdɪkʃən/, calculation /ˌkælkjuˈleɪʃn̩/, notification /ˌnoʊtɪfɪˈkeɪʃn̩/, sunshine /ˈsʌnʃaɪn/
- Mots longs — placez bien l’accent: resilience /ɹɪˈzɪl.ɪ.əns/, undecided /ˌʌndɪˈsaɪ̯.dɪd/, mathematics /mæθ(.ə)ˈmæt.ɪks/, contradiction /ˌkɑːntɹəˈdɪkʃən/, notification /ˌnoʊtɪfɪˈkeɪʃn̩/
Les sons difficiles pour les francophones :
- /tʃ/ et /dʒ/ — à ne pas adoucir en « ch » et « j »: outage /ˈaʊ.tɪd͡ʒ/, discharge /dɪsˈtʃɑɹdʒ/, breach /ˈbɹiːt͡ʃ/, checkout /ˈt͡ʃɛkˌaʊt/, charger /ˈt͡ʃɑɹd͡ʒɚ/
- /r/ anglais — langue recourbée, sans frotter la gorge: grid /ɡɹɪd/, spreadsheet /ˈspɹɛd.ʃit/, resilience /ɹɪˈzɪl.ɪ.əns/, warranty /ˈwɔɹ.ən.ti/, meter /ˈmitəɹ/
Comment s’entraîner avec cette vidéo
- Écoutez la vidéo en entier une fois sans parler et notez les mots que vous ne connaissez pas.
- Commencez à la vitesse 0,75×, répétez phrase par phrase, puis revenez à la vitesse normale quand cela devient facile.
- Enregistrez-vous et comparez avec l’original, en faisant attention à des mots comme grid, kilowatt, outage.
Qu'est-ce que la technique du Shadowing ?
Le Shadowing est une technique d'apprentissage des langues fondée sur la science, développée à l'origine pour la formation des interprètes professionnels. Le principe est simple mais puissant : vous écoutez de l'anglais natif et le répétez immédiatement à voix haute — comme une ombre suivant le locuteur avec un décalage de 1 à 2 secondes. Les recherches montrent une amélioration significative de la précision de la prononciation, de l'intonation, du rythme, des liaisons, de la compréhension orale et de la fluidité.