6 ms·

AC is easy, because it is needed when there is a lot of sun. The challenge is heating. Feeding to the grid during summer and buying back during winter does not

AC is easy, because it is needed when there is a lot of sun. The challenge is heating. Feeding to the grid during summer and buying back during winter does not solve any problem. For non-heating use day/night cycles can be solved by batteries. For non-heating use over-provisioning to catch ambient light could even make it work during winter, no grid needed. But for heating, over-provisioning to run a heat-pump on ambient light does not seem viable. Year-cycle storage is complex (e.g., hydrogen, maybe high-temperature to store heat, ...). A solution can be collectors to create electricity which is then stored by a second system. An alternative might be collectors that don't produce electricity but something that can be stored directly. Difficult choice to go all-in on PV for planned use of 25 years today when there might be a more storage-friendly solution available in 10 years.

HyperSane 4y ago
cfn 4y ago
This mirrors my experience. I was offgrid for over six years and we had enough solar panels and batteries to produce all the power we needed and then some (even in the Winter as this was in South Europe). But for heating we used wood. I suppose we could have run a 1-2kw heater for a few hours every night but it would have reduced the batteries life which were quite expensive.
freddie_mercury 4y ago
> AC is easy, because it is needed when there is a lot of sun. This isn't universally true and I think shows a lack of intuitive familiarity with climates that aren't North America or Europe. Where I live the over night low will be 26c (79f). With high humidity that's a "RealFeel(r)" of 31c (88f). Most people find that uncomfortable to sleep in, especially if they didn't grow up in it. Most people I know have their air conditioning on overnight. There are plenty of places where night time temperatures, especially when combined with humidity, still result in air conditioning -- assuming the country is rich enough to afford it. Which increasingly many are. Heck, today is overcast with no sun but it is still 33c with a "RealFeel" of 40c.
- bryanlarsen 4y ago
  Is your house so badly sealed that if you air condition during sunlight hours it will become uncomfortable got at night? A 3 degree temperature differential between inside and outside will take a long time to equalize. My parents old house had wood heat. In other words it took a lot of effort, so we'd start the fire as rarely as possible. Which was every second or third day when the outside temperature was -20c. You don't have 12 inch walls like my parents did, but you don't have a 40c temperature differential either...
  - freddie_mercury 4y ago
    There's no such thing as whole house air conditioning here. Running air conditioning in the living room during the day isn't going to do anything for the bedroom at night. Also houses are often empty during much of the day due to people being at work/school. So they get home at 6pm and turn on the air conditioning. They certainly wouldn't leave it running all day when no one is home.
    - bryanlarsen 4y ago
      Circling back to the point of the article, they might leave the air conditioning running in an empty house if the power was free.
spockz 4y ago
Here in the Netherlands where we have relatively easy access to the ground and ability to drill, we are starting to make more use of ground temperature. With either narrow 50m deep installs to reach a place with a steady 12 degrees Celsius, or more top layer but wider installs. A heat pump is then used to exchange the heat of ground to the heat of the house. For both heating and hot running water. Then an additional option is to cool the house in summer by extracting the heat from the house and pumping it into the ground to be extracted during winter. This is interesting because, especially in combination with floor heating, this can heat a house on the solar generation in winter. Sadly these systems are expensive to install after building the house. But it can be done, especially the less specialised wider top soil solutions.
mahkeiro 4y ago
Heating (and AC) are not problems solved by pouring more energy in your home but with insulation.A passive house is a reality even for cold climate, and they don't need storage for cooling/heating. Then you are left with your appliance that have to run outside of production time, but this is rather small.
- nerdawson 4y ago
  Insulation alone doesn't necessarily solve for AC / cooling. Modern houses with more insulation than ever are some of the most prone to overheating. So much so that the UK's latest update to building regulations, Part O, are specifically targeted at overheating. Insulation slows the transfer of heat so in theory it should help on hot days as well as cold. The problem is modern houses lack thermal mass to smooth out temperature changes. They're quick to heat up whether wanted or not. So, you have solar gain heating up rooms on a sunny day, better insulation reducing heat transfer, and high levels of airtightness trapping the indoor air. Building design has to adapt for a changing climate. Many existing homes will need air conditioning to maintain a comfortable environment regardless of how well you insulate them.
freemint 4y ago
> Feeding to the grid during summer and buying back during winter does not solve any problem. It is summer or spring all year around. The problem is your grid it so small.

HyperSane 4y ago

cfn 4y ago

This mirrors my experience. I was offgrid for over six years and we had enough solar panels and batteries to produce all the power we needed and then some (even in the Winter as this was in South Europe). But for heating we used wood. I suppose we could have run a 1-2kw heater for a few hours every night but it would have reduced the batteries life which were quite expensive.

freddie_mercury 4y ago

> AC is easy, because it is needed when there is a lot of sun. This isn't universally true and I think shows a lack of intuitive familiarity with climates that aren't North America or Europe. Where I live the over night low will be 26c (79f). With high humidity that's a "RealFeel(r)" of 31c (88f). Most people find that uncomfortable to sleep in, especially if they didn't grow up in it. Most people I know have their air conditioning on overnight. There are plenty of places where night time temperatures, especially when combined with humidity, still result in air conditioning -- assuming the country is rich enough to afford it. Which increasingly many are. Heck, today is overcast with no sun but it is still 33c with a "RealFeel" of 40c.

bryanlarsen 4y ago
Is your house so badly sealed that if you air condition during sunlight hours it will become uncomfortable got at night? A 3 degree temperature differential between inside and outside will take a long time to equalize. My parents old house had wood heat. In other words it took a lot of effort, so we'd start the fire as rarely as possible. Which was every second or third day when the outside temperature was -20c. You don't have 12 inch walls like my parents did, but you don't have a 40c temperature differential either...
- freddie_mercury 4y ago
  There's no such thing as whole house air conditioning here. Running air conditioning in the living room during the day isn't going to do anything for the bedroom at night. Also houses are often empty during much of the day due to people being at work/school. So they get home at 6pm and turn on the air conditioning. They certainly wouldn't leave it running all day when no one is home.
  - bryanlarsen 4y ago
    Circling back to the point of the article, they might leave the air conditioning running in an empty house if the power was free.

spockz 4y ago

Here in the Netherlands where we have relatively easy access to the ground and ability to drill, we are starting to make more use of ground temperature. With either narrow 50m deep installs to reach a place with a steady 12 degrees Celsius, or more top layer but wider installs. A heat pump is then used to exchange the heat of ground to the heat of the house. For both heating and hot running water. Then an additional option is to cool the house in summer by extracting the heat from the house and pumping it into the ground to be extracted during winter. This is interesting because, especially in combination with floor heating, this can heat a house on the solar generation in winter. Sadly these systems are expensive to install after building the house. But it can be done, especially the less specialised wider top soil solutions.

mahkeiro 4y ago

Heating (and AC) are not problems solved by pouring more energy in your home but with insulation.A passive house is a reality even for cold climate, and they don't need storage for cooling/heating. Then you are left with your appliance that have to run outside of production time, but this is rather small.

nerdawson 4y ago
Insulation alone doesn't necessarily solve for AC / cooling. Modern houses with more insulation than ever are some of the most prone to overheating. So much so that the UK's latest update to building regulations, Part O, are specifically targeted at overheating. Insulation slows the transfer of heat so in theory it should help on hot days as well as cold. The problem is modern houses lack thermal mass to smooth out temperature changes. They're quick to heat up whether wanted or not. So, you have solar gain heating up rooms on a sunny day, better insulation reducing heat transfer, and high levels of airtightness trapping the indoor air. Building design has to adapt for a changing climate. Many existing homes will need air conditioning to maintain a comfortable environment regardless of how well you insulate them.

freemint 4y ago

> Feeding to the grid during summer and buying back during winter does not solve any problem. It is summer or spring all year around. The problem is your grid it so small.