7 ms·

Think of your home as (small) profitable power plant

21 points by _m_benjamin 3y ago

M95D 3y ago
I wish I had my own roof.
- PaulKeeble 3y ago
  Have a look for cooperative solar farm schemes. There might be a local one or a state/national one you can invest into to offset your electricity bill. There are more popular in the EU and UK but they are bound to come to the USA due to how cheap Solar is for power now.
- bluescrn 3y ago
  In the same position. There's very few 'green tech' options for apartment dwellers. It all has the prerequisite of owning a large and very expensive home. You need significant space for a solar(+battery) installation. Or for a heat pump. Charging an EV at home requires you to have a garage or driveway, and we all know that public chargers are going to do a massive bait+switch, hiking prices way up once companies running them have established local monopolies and demand has built up. Even a bike or e-scooter can be a pain to own without secure storage space if you've got to carry it up/down stairs each time you want to use it.
  - 1234letshaveatw 3y ago
    A large and very expensive home or... A cheap and small one works as well. A garage or driveway or... a dirt 2 track also does the trick. No need to overstate things.
- _m_benjamin 3y ago
  I own my place but only the floor. I'm in a 2-unit condo, so I don't own the roof per se. That means if the guy upstairs has a toilet overflow, I get the downstream effects (that happened; not fun). I wish I had a standalone home (floor to roof and all in between) - especially in an area where the retrofits from the article were possible. I've been 11 years in my current place and now I _really_ know what to look for next time. I suppose it's like anything: once you've spent enough time to see how small cracks will widen; enough time to know what gutter configurations will cause; where the architecture might collect rain and cause flooding; where rodents can find ingress -- once you're pretty battle-worn, a new house shines different. My wife is looking at places and because I've run maintenance, we look at things quite differently.
_m_benjamin 3y ago
Use federal incentives, spend USD $75k, money back in 6 years, then turn a small profit from then on. I need to move.
thoma4s 3y ago
https://archive.is/e1xN9 https://archive.is/e1xN9
manfre 3y ago
I'm mostly curious about how a normal person can get a zero interest loan?
- why_only_15 3y ago
  I assume a government program for batteries, but not sure.
- krallja 3y ago
  Get the loan in 2019, with a generous markup on the product so you don’t notice the interest is baked into the price.
- kylert 3y ago
  Mass Save have various low or no interest loans available for improving energy efficiency and generating clean energy if you qualify for them. I used a Mass Save HEAT Loan about 10y ago to replace my old oil burning furnace with a gas furnace and paid zero interest. The new gas furnace had requirements on its efficiency. While Mass Save sounds really generous, it's being funded by everyone in their electric bill. So in a way, you've already paid into the program. You might as well get something out by calling up a Mass Save auditor and seeing what you can get out of it.
- ldoughty 3y ago
  Credit cards were offering 0% interest for new customers for up to nearly 2 years (with good credit) If I did a project like this, I certainly would max out a deal like that, and prioritize that payout over the duration. If it was from a bank and 3+ years, I'd love to know how to do that too
lucioperca 3y ago
These suburbia homes are still pretty bad deal for the public. Lots of infrastructure cost come with them like car infrastructure etc.
- AlgorithmicTime 3y ago
  [dead]
- some_random 3y ago
  As a society, we've decided that we want lots of infrastructure including car infrastructure.
  - dartos 3y ago
    Yknow, in the US, I think it was more auto industry lobbying in the 20th century that led us to the whole “stroads” situation we have. People didn’t like having 3 lane roads right in their path to walk to the grocery store. The municipal solution was to ensure everyone needed to drive everywhere.
    - some_random 3y ago
      The car infrastructure you were referring to is more than just stroads and mandatory vehicle ownership. I know that's all your favorite youtubers talk about, but there are actually other aspects.
      - dartos 3y ago
        Hey friend, how about instead of writing a comment that does nothing but sound condescending, you add something to the discussion. What “more” are you talking about? I’m very interested in this.
        some_random 3y ago
        Yeah absolutely, here's some reading to get you started! https://en.wikipedia.org/wiki/Types_of_road https://en.wikipedia.org/wiki/Types_of_road
eitally 3y ago
A lot of these [expensive] incentives are already being wound down, and the ones under control of utilities (e.g. net metering) can radically impact the ROI of things like solar installations. It'll be interesting to see how things stabilize in California over the next few years now that new residential solar doesn't make sense for almost anyone [unless they also have batteries and drive EVs, since electricity is now more expensive than running most gas-powered cars]. Additionally, why would most homeowners spend this kind of money when the vast majority of people only stay in a give house for ~7 years total? The incentives are great, but I don't see substantial changes happening unless it becomes a true no-brainer to replace fossil fuel systems and inefficient infrastructure (windows, roofs, insulation) with updated materiel. Blowing in more insulation is cheap and easy, but most Americans don't have a rainy day fund that would make replacing a furnace with heat pumps something they casually decide makes sense... or gas appliances with electric, or a new roof, etc.
hattmall 3y ago
75,000 in savings over 6 years is $12,500 a year, which means this person's utility bills were over $1000 a month!? I know that my house is wildly inefficient and $300-$400 a month is the worst it gets with extreme weather. Talking with friends and family my bills are higher than normal, most are around $200 and less in the milder months. A quick search shows $469 being average us Utility bills and that includes water, trash and internet. I would also like to know, what size the panels and battery are as well.
- PaulKeeble 3y ago
  Typically a panel these days is going to be around 400W, so the 33 panels is likely somewhere around 13KWp. I am not sure which Needham (Boston?) they are referring to but in Boston would produce annually about 15 MW/h. As to the battery the price gives us an idea of its size, $23,000 dollars. On the expensive side with a Tesla powerwall you get 13.5KW/h for about $9000, its possible to get about 2/3 that price with other systems. So somewhere in the region of 40-50KW/h of storage. Hope that helps.
- simonjgreen 3y ago
  Presumably the export has been factored in to this, so making money not just saving
- PH95VuimJjqBqy 3y ago
  > I know that my house is wildly inefficient and $300-$400 a month is the worst it gets with extreme weather. I lived in a house for 4-5 years where it struggled to stay cool in the summer and the bills would get up to $300-$400 a month as well. One year I had an HVAC guy out to clean my unit and I was asking him questions (which I did every year) and this was the first guy to tell me when he generally sees issues like that it's insulation related. He climbed up into my attic and recommended I add more insulation. I did so and the relief was shocking. Obviously I understand how insulation can help but what shocked me was just how large a difference more insulation helped in a house that already had insulation. Lessson learned that many times us technical folks know but don't truly understand. Every other HVAC person had just said the unit was on the small side. So you may take a look at the insulation in the house, even something as laying more insulation in your attic may help tremendously.
technotarek 3y ago
One man’s experience in DC (where the SRECs are crazy valuable): Installed 10Mwh system in 2021 for ~$40k. After federal tax credits, SREC earnings, reductions in electric bills, and payments from electric co for over production, we have $7k left to recoup in only 3 years. And that ignores savings from the gas we’re not spending on charging the PHEV. I know it’s a luxury to have, but there’s also some pride value (clearly!). Fortunate circumstance if you’re in the right place and have the cash. I wish the investment was more broadly accessible.
- djaychela 3y ago
  10MWh?
  - technotarek 3y ago
    Sorry, yes 10KWh!
  - simonjgreen 3y ago
    Surely 10 kWh
  - robin_reala 3y ago
    Presumably KWh? That’d be ~25 rather than ~25,000 panels.
  - PaulKeeble 3y ago
    Could be an annual measure of expected output.
    - midasuni 3y ago
      That’s the only thing which makes sense with the magnitude and unit used
  - sumtechguy 3y ago
    I have a 7k system. In 4 months since I have installed I have made about 3MW? Would have been more but ... winter. Maybe that is what they mean?
PaulKeeble 3y ago
Solar and batteries pays off pretty quickly and can bring you to a net zero position on electrical needs fairly easily (excess sold in summer, importing in the winter). On an annual basis I now power half of another home in addition to my own. If I take the total expected output over 25 years my electricity cost is 1/4 of what it would be from the grid per KW/h. I went 6 months last year importing almost nothing from the grid. In the UK at least batteries and an inverter are actually quicker to pay off using an economy 7 electricity tariff since power overnight is less than half the price of during the day and is typically from Wind power and imported Nuclear from France. That can pay off in less than 4 years and will last 10-15 with li-po. If you don't have a roof to put solar on then there are some cooperative schemes where you can own part of a solar/wind installation and still save on your bill. A national one is https://rippleenergy.com/ https://rippleenergy.com/ but there may be more local schemes that you could help fund and get the payback from, residents are banding together to build solar farms all over the country. The big energy companies have messed up this transition to green energy terribly and its considerably cheaper to make your own power than buy from them, which lets be honest it shouldn't be.
- midasuni 3y ago
  I’ve been wondering about just battery and inverter and using an agile tariff. How large an inverter did you get and what happens at full load (oven, kettle, electric shower and hairdryer all on at same time) which is presumably combined higher than the inverter?
  - PaulKeeble 3y ago
    My inverter is 3.6KW and can put out 4KW to the home. There is a normal limit for 3.6 in the UK for max export unless you do a more complex DNO99 application so that is the typical values. Above that you pull from the grid for the excess. I can run the oven (1.5KW) and kettle (2KW) but not a hair drier in addition. You change your behaviour a little with these solutions, you put the washing and dishwasher on when you have excess power or do them at night when it's cheap,you wait for the kettle to finish before hair drying. But the price isn't really driven by these rare combined events anyway, they don't matter in the grand scheme of things as most of your needs get met by the inverter and batteries.
ComputerGuru 3y ago
To me, the obvious reason why solar would be a gamble is that I have no guarantee I’ll be living here in the same home five years - let alone twenty - from now and I can’t take it with me when/if I move.
- zie 3y ago
  If you don't think you will be living there in 5 years, you probably shouldn't have bought the place, as the up to 10% or more transaction costs will eat you alive.
  - ComputerGuru 3y ago
    In five more years, not "for five years."
- midasuni 3y ago
  As a buyer I would value an existing solar/battery system, especially one with actual generation data, thus would pay more
blagie 3y ago
My problem is whenever I've seen these numbers, they were completely baked. "The total price tag for the entire home project was roughly $75,000, after rebates. But Tuttelman says it will pay for itself in about six years through energy cost savings." The costs seem right. I've priced this. The savings are nonsense. I don't spend $75k in utility bills in six years. "Other benefits include the stress savings of not having to guess when a furnace, which typically lasts about 15 years, is on its last legs." My boiler is going strong after forty years, and the technician who looked at it last said this was typical and there's no reason to think it won't last another forty. I periodically need to replace a control board, which I should learn to do myself. In contrast, the system described -- with heat pumps, solar, and whatnot, has a lot more parts and things to go wrong. I'm equally sceptical of the current direct environmental benefit. If I e.g. tossed out my gas-powered car and bought a Tesla, I'd have the environmental cost of manufacturing a Tesla. That would need to be lower than the environmental cost of the gas I'll use for the rest of the life of my car. I don't think it is. There are reasons to buy this stuff (e.g. to support the green industry). That doesn't excuse the propaganda and the fake numbers.
- ljf 3y ago
  Agree on some points here - in the UK I spend about £300 combined on gas and electricity. But your boiler sounds interesting - if it is 40 years old it will be wildly inefficient compared to boilers from the last few years - on changing our 10yo boiler we saved about £100 a month across the year - But I only expect that boiler to last 10 to 15 years - but that is OK, by then I'm sure I'll be moving to electric heating and hot water, as I can only assume gas will be phased out.
  - blagie 3y ago
    I'm not quite sure how a boiler can be efficient or inefficient. It seems like for every watt of power going in, I get one watt of heat out. That's basic thermodynamics. If heat doesn't make it into the water, it still ultimately heats my house. Perhaps language issue? My boiler heats the water for my radiators which heat my house. That's not the same as my hot water tank, which heats running hot water. Here, where modern ones do tend to leak less heat into the air, and these do have a limited lifespan as the tank corrodes. Can you explain? I feel like the only way I could go up in efficiency is if I sucked in heat from the outdoors with a heat pump.
ProllyInfamous 3y ago
I recently replaced an electric instahot (on-demand) water heater with a tank hybrid heater. In addition to dehumidifying and cooling the basement, it uses about a quarter of the electricity (from 10%, monthly, to 3% kWH). During the winter, I keep the tub water plugged up for the heat pump to re-absorb... REDUCE, re-use, recycle, generate.
brk 3y ago
I've done these calculations, particularly after putting an 11.6Kw solar array on our last house, which was in St. Petersburg, FL, one of the sunniest places in the US. We sold the house after having the system for ~6.5 years, but we were tracking for a 9 year ROI. My cost was ~$23K out of pocket at the time, with power bills of $500-$800/mo., depending on time of year. I think our average daily consumption was 69Kwh, and the system produced the majority of that most days. Assuming an average power bill of $600/mo., $23K would cover roughly 3 years of power bills. However, if the money was invested in a decent-ish portfolio, it would be earning some interest along the way, which could stretch what it covers to 5+ years. Anyway, when I did all the math, the solar panels never really made money, but what they did was smooth out our monthly expenses and gave some hedge against rate increases. The new house is the same general area, and our use is about the same, but going to wait to see if solar takes a bigger decrease in cost before doing another array. It's mostly maintenance-free, but I did not output decline when the panels got dirty, and one panel died about 1 year after installation (and by then the installer company had gone out of business).
- friend_and_foe 3y ago
  I'm curious, it boggles my mind how people get energy bills that high. Do you pay 90¢ a kilowatt hour or something? What are you doing in your house to use that much electricity?
  - brk 3y ago
    In the previous house we had 3 A/C units for the house (4T, 4T, 1T), and two on the boat (1.3T, 1.3T) that ran pretty consistently. That was the vast majority of the consumption. We had an electric clothes dryer, which would run a few hours a week. And electric oven and cooktop, which had minimal use (mostly cook outdoors). The only other large loads were an electric water heater and an elevator, plus a few PCs that were on 24/7.

21 points by _m_benjamin 3y ago

M95D 3y ago

I wish I had my own roof.

PaulKeeble 3y ago
Have a look for cooperative solar farm schemes. There might be a local one or a state/national one you can invest into to offset your electricity bill. There are more popular in the EU and UK but they are bound to come to the USA due to how cheap Solar is for power now.
bluescrn 3y ago
In the same position. There's very few 'green tech' options for apartment dwellers. It all has the prerequisite of owning a large and very expensive home. You need significant space for a solar(+battery) installation. Or for a heat pump. Charging an EV at home requires you to have a garage or driveway, and we all know that public chargers are going to do a massive bait+switch, hiking prices way up once companies running them have established local monopolies and demand has built up. Even a bike or e-scooter can be a pain to own without secure storage space if you've got to carry it up/down stairs each time you want to use it.
- 1234letshaveatw 3y ago
  A large and very expensive home or... A cheap and small one works as well. A garage or driveway or... a dirt 2 track also does the trick. No need to overstate things.
_m_benjamin 3y ago
I own my place but only the floor. I'm in a 2-unit condo, so I don't own the roof per se. That means if the guy upstairs has a toilet overflow, I get the downstream effects (that happened; not fun). I wish I had a standalone home (floor to roof and all in between) - especially in an area where the retrofits from the article were possible. I've been 11 years in my current place and now I _really_ know what to look for next time. I suppose it's like anything: once you've spent enough time to see how small cracks will widen; enough time to know what gutter configurations will cause; where the architecture might collect rain and cause flooding; where rodents can find ingress -- once you're pretty battle-worn, a new house shines different. My wife is looking at places and because I've run maintenance, we look at things quite differently.

_m_benjamin 3y ago

Use federal incentives, spend USD $75k, money back in 6 years, then turn a small profit from then on. I need to move.

thoma4s 3y ago

https://archive.is/e1xN9 https://archive.is/e1xN9

manfre 3y ago

I'm mostly curious about how a normal person can get a zero interest loan?

why_only_15 3y ago
I assume a government program for batteries, but not sure.
krallja 3y ago
Get the loan in 2019, with a generous markup on the product so you don’t notice the interest is baked into the price.
kylert 3y ago
Mass Save have various low or no interest loans available for improving energy efficiency and generating clean energy if you qualify for them. I used a Mass Save HEAT Loan about 10y ago to replace my old oil burning furnace with a gas furnace and paid zero interest. The new gas furnace had requirements on its efficiency. While Mass Save sounds really generous, it's being funded by everyone in their electric bill. So in a way, you've already paid into the program. You might as well get something out by calling up a Mass Save auditor and seeing what you can get out of it.
ldoughty 3y ago
Credit cards were offering 0% interest for new customers for up to nearly 2 years (with good credit) If I did a project like this, I certainly would max out a deal like that, and prioritize that payout over the duration. If it was from a bank and 3+ years, I'd love to know how to do that too

lucioperca 3y ago

These suburbia homes are still pretty bad deal for the public. Lots of infrastructure cost come with them like car infrastructure etc.

AlgorithmicTime 3y ago
[dead]
some_random 3y ago
As a society, we've decided that we want lots of infrastructure including car infrastructure.
- dartos 3y ago
  Yknow, in the US, I think it was more auto industry lobbying in the 20th century that led us to the whole “stroads” situation we have. People didn’t like having 3 lane roads right in their path to walk to the grocery store. The municipal solution was to ensure everyone needed to drive everywhere.
  - some_random 3y ago
    The car infrastructure you were referring to is more than just stroads and mandatory vehicle ownership. I know that's all your favorite youtubers talk about, but there are actually other aspects.
    - dartos 3y ago
      Hey friend, how about instead of writing a comment that does nothing but sound condescending, you add something to the discussion. What “more” are you talking about? I’m very interested in this.
      - some_random 3y ago
        Yeah absolutely, here's some reading to get you started! https://en.wikipedia.org/wiki/Types_of_road https://en.wikipedia.org/wiki/Types_of_road

eitally 3y ago

A lot of these [expensive] incentives are already being wound down, and the ones under control of utilities (e.g. net metering) can radically impact the ROI of things like solar installations. It'll be interesting to see how things stabilize in California over the next few years now that new residential solar doesn't make sense for almost anyone [unless they also have batteries and drive EVs, since electricity is now more expensive than running most gas-powered cars]. Additionally, why would most homeowners spend this kind of money when the vast majority of people only stay in a give house for ~7 years total? The incentives are great, but I don't see substantial changes happening unless it becomes a true no-brainer to replace fossil fuel systems and inefficient infrastructure (windows, roofs, insulation) with updated materiel. Blowing in more insulation is cheap and easy, but most Americans don't have a rainy day fund that would make replacing a furnace with heat pumps something they casually decide makes sense... or gas appliances with electric, or a new roof, etc.

hattmall 3y ago

75,000 in savings over 6 years is $12,500 a year, which means this person's utility bills were over $1000 a month!? I know that my house is wildly inefficient and $300-$400 a month is the worst it gets with extreme weather. Talking with friends and family my bills are higher than normal, most are around $200 and less in the milder months. A quick search shows $469 being average us Utility bills and that includes water, trash and internet. I would also like to know, what size the panels and battery are as well.

PaulKeeble 3y ago
Typically a panel these days is going to be around 400W, so the 33 panels is likely somewhere around 13KWp. I am not sure which Needham (Boston?) they are referring to but in Boston would produce annually about 15 MW/h. As to the battery the price gives us an idea of its size, $23,000 dollars. On the expensive side with a Tesla powerwall you get 13.5KW/h for about $9000, its possible to get about 2/3 that price with other systems. So somewhere in the region of 40-50KW/h of storage. Hope that helps.
simonjgreen 3y ago
Presumably the export has been factored in to this, so making money not just saving
PH95VuimJjqBqy 3y ago
> I know that my house is wildly inefficient and $300-$400 a month is the worst it gets with extreme weather. I lived in a house for 4-5 years where it struggled to stay cool in the summer and the bills would get up to $300-$400 a month as well. One year I had an HVAC guy out to clean my unit and I was asking him questions (which I did every year) and this was the first guy to tell me when he generally sees issues like that it's insulation related. He climbed up into my attic and recommended I add more insulation. I did so and the relief was shocking. Obviously I understand how insulation can help but what shocked me was just how large a difference more insulation helped in a house that already had insulation. Lessson learned that many times us technical folks know but don't truly understand. Every other HVAC person had just said the unit was on the small side. So you may take a look at the insulation in the house, even something as laying more insulation in your attic may help tremendously.

technotarek 3y ago

One man’s experience in DC (where the SRECs are crazy valuable): Installed 10Mwh system in 2021 for ~$40k. After federal tax credits, SREC earnings, reductions in electric bills, and payments from electric co for over production, we have $7k left to recoup in only 3 years. And that ignores savings from the gas we’re not spending on charging the PHEV. I know it’s a luxury to have, but there’s also some pride value (clearly!). Fortunate circumstance if you’re in the right place and have the cash. I wish the investment was more broadly accessible.

djaychela 3y ago
10MWh?
- technotarek 3y ago
  Sorry, yes 10KWh!
- simonjgreen 3y ago
  Surely 10 kWh
- robin_reala 3y ago
  Presumably KWh? That’d be ~25 rather than ~25,000 panels.
- PaulKeeble 3y ago
  Could be an annual measure of expected output.
  - midasuni 3y ago
    That’s the only thing which makes sense with the magnitude and unit used
- sumtechguy 3y ago
  I have a 7k system. In 4 months since I have installed I have made about 3MW? Would have been more but ... winter. Maybe that is what they mean?

PaulKeeble 3y ago

Solar and batteries pays off pretty quickly and can bring you to a net zero position on electrical needs fairly easily (excess sold in summer, importing in the winter). On an annual basis I now power half of another home in addition to my own. If I take the total expected output over 25 years my electricity cost is 1/4 of what it would be from the grid per KW/h. I went 6 months last year importing almost nothing from the grid. In the UK at least batteries and an inverter are actually quicker to pay off using an economy 7 electricity tariff since power overnight is less than half the price of during the day and is typically from Wind power and imported Nuclear from France. That can pay off in less than 4 years and will last 10-15 with li-po. If you don't have a roof to put solar on then there are some cooperative schemes where you can own part of a solar/wind installation and still save on your bill. A national one is https://rippleenergy.com/ https://rippleenergy.com/ but there may be more local schemes that you could help fund and get the payback from, residents are banding together to build solar farms all over the country. The big energy companies have messed up this transition to green energy terribly and its considerably cheaper to make your own power than buy from them, which lets be honest it shouldn't be.

midasuni 3y ago
I’ve been wondering about just battery and inverter and using an agile tariff. How large an inverter did you get and what happens at full load (oven, kettle, electric shower and hairdryer all on at same time) which is presumably combined higher than the inverter?
- PaulKeeble 3y ago
  My inverter is 3.6KW and can put out 4KW to the home. There is a normal limit for 3.6 in the UK for max export unless you do a more complex DNO99 application so that is the typical values. Above that you pull from the grid for the excess. I can run the oven (1.5KW) and kettle (2KW) but not a hair drier in addition. You change your behaviour a little with these solutions, you put the washing and dishwasher on when you have excess power or do them at night when it's cheap,you wait for the kettle to finish before hair drying. But the price isn't really driven by these rare combined events anyway, they don't matter in the grand scheme of things as most of your needs get met by the inverter and batteries.

ComputerGuru 3y ago

To me, the obvious reason why solar would be a gamble is that I have no guarantee I’ll be living here in the same home five years - let alone twenty - from now and I can’t take it with me when/if I move.

zie 3y ago
If you don't think you will be living there in 5 years, you probably shouldn't have bought the place, as the up to 10% or more transaction costs will eat you alive.
- ComputerGuru 3y ago
  In five more years, not "for five years."
midasuni 3y ago
As a buyer I would value an existing solar/battery system, especially one with actual generation data, thus would pay more

blagie 3y ago

My problem is whenever I've seen these numbers, they were completely baked. "The total price tag for the entire home project was roughly $75,000, after rebates. But Tuttelman says it will pay for itself in about six years through energy cost savings." The costs seem right. I've priced this. The savings are nonsense. I don't spend $75k in utility bills in six years. "Other benefits include the stress savings of not having to guess when a furnace, which typically lasts about 15 years, is on its last legs." My boiler is going strong after forty years, and the technician who looked at it last said this was typical and there's no reason to think it won't last another forty. I periodically need to replace a control board, which I should learn to do myself. In contrast, the system described -- with heat pumps, solar, and whatnot, has a lot more parts and things to go wrong. I'm equally sceptical of the current direct environmental benefit. If I e.g. tossed out my gas-powered car and bought a Tesla, I'd have the environmental cost of manufacturing a Tesla. That would need to be lower than the environmental cost of the gas I'll use for the rest of the life of my car. I don't think it is. There are reasons to buy this stuff (e.g. to support the green industry). That doesn't excuse the propaganda and the fake numbers.

ljf 3y ago
Agree on some points here - in the UK I spend about £300 combined on gas and electricity. But your boiler sounds interesting - if it is 40 years old it will be wildly inefficient compared to boilers from the last few years - on changing our 10yo boiler we saved about £100 a month across the year - But I only expect that boiler to last 10 to 15 years - but that is OK, by then I'm sure I'll be moving to electric heating and hot water, as I can only assume gas will be phased out.
- blagie 3y ago
  I'm not quite sure how a boiler can be efficient or inefficient. It seems like for every watt of power going in, I get one watt of heat out. That's basic thermodynamics. If heat doesn't make it into the water, it still ultimately heats my house. Perhaps language issue? My boiler heats the water for my radiators which heat my house. That's not the same as my hot water tank, which heats running hot water. Here, where modern ones do tend to leak less heat into the air, and these do have a limited lifespan as the tank corrodes. Can you explain? I feel like the only way I could go up in efficiency is if I sucked in heat from the outdoors with a heat pump.

ProllyInfamous 3y ago

I recently replaced an electric instahot (on-demand) water heater with a tank hybrid heater. In addition to dehumidifying and cooling the basement, it uses about a quarter of the electricity (from 10%, monthly, to 3% kWH). During the winter, I keep the tub water plugged up for the heat pump to re-absorb... REDUCE, re-use, recycle, generate.

brk 3y ago

I've done these calculations, particularly after putting an 11.6Kw solar array on our last house, which was in St. Petersburg, FL, one of the sunniest places in the US. We sold the house after having the system for ~6.5 years, but we were tracking for a 9 year ROI. My cost was ~$23K out of pocket at the time, with power bills of $500-$800/mo., depending on time of year. I think our average daily consumption was 69Kwh, and the system produced the majority of that most days. Assuming an average power bill of $600/mo., $23K would cover roughly 3 years of power bills. However, if the money was invested in a decent-ish portfolio, it would be earning some interest along the way, which could stretch what it covers to 5+ years. Anyway, when I did all the math, the solar panels never really made money, but what they did was smooth out our monthly expenses and gave some hedge against rate increases. The new house is the same general area, and our use is about the same, but going to wait to see if solar takes a bigger decrease in cost before doing another array. It's mostly maintenance-free, but I did not output decline when the panels got dirty, and one panel died about 1 year after installation (and by then the installer company had gone out of business).

friend_and_foe 3y ago
I'm curious, it boggles my mind how people get energy bills that high. Do you pay 90¢ a kilowatt hour or something? What are you doing in your house to use that much electricity?
- brk 3y ago
  In the previous house we had 3 A/C units for the house (4T, 4T, 1T), and two on the boat (1.3T, 1.3T) that ran pretty consistently. That was the vast majority of the consumption. We had an electric clothes dryer, which would run a few hours a week. And electric oven and cooktop, which had minimal use (mostly cook outdoors). The only other large loads were an electric water heater and an elevator, plus a few PCs that were on 24/7.