4 ms·

I've built a new home, NOT off-grid but capable of a limited autonomy and I'm FAR less optimistic than the author: first of all I'm living far south (French Alp

by kkfx 4y ago

I've built a new home, NOT off-grid but capable of a limited autonomy and I'm FAR less optimistic than the author: first of all I'm living far south (French Alps of the south) so in a far more p.v. friendly place, with less cold for less time in winter and still a circadian thermal Δ that makes cooling needed only when the Sun shine. It's not a cabin but a home so with far more room for equipment. For the home I see I need to double my p.v. to 10kWp JUST to achieve a bit more than 50% self-consumption of the year, from 72% maximum in spring/summer to 35% of November-February. WFH to recharge A BIT from p.v. my EV with a realistic relative autonomy I need around 10kWp three phase, not single phase. Witch means three time the plant and it's costs, space etc. Still NOT reaching autonomy. Not counting the usable life of LiFeP storage and NMC cars... With my actual setup I can POTENTIALLY halving by home storage operation life be autonomous just from late May to September being VERY attentive in all I do, without counting the car. With a theoretical 10kWp x 3 I might be reasonably autonomous also for car (limiting my trips much) just from June to August. Actually my time-machine is offline and my body live 365 days per year, regardless of the season and actual hours of Sunlight or heating/cooling needs... Oh, and I also need to eat, being unable to create my own food out of my land (except for VERY limited amount of veggies, fish and meat casually hunted in a limited period of the year)... Oh, and of course I need many gears, starting from p.v. who is built by factories unable to run on p.v. themselves.............

Ballas 4y ago
You should really do an energy audit to figure out why you are using so much power. There is likely a more optimal way of spending your money to optimize your energy requirements. I have 5kWp and that generates more than double my needs on average (albeit in an even more solar friendly location than you).
- kkfx 4y ago
  It's not that much power, it's simply the normal home needs: being a new home it's ALL electric, heating/cooling, cooking, hot water, ... if you have a classic home where for instance heating/cooling is not needed of course the story SEEMS different until you do a bit of conversion: - 1 standard m³ CH₄ is ~10.36kWh - LPG in standard m³ is ~12.80kWh in kg ~10.87kWh - 1kg of pellets ~4-5 kWh - 1 liter of heating oil (it's name vary from country to country, but it essentially diesel in the west) is ~11.1kWh - 1kg of reasonably dry coal is ~10 kWh Once you compute ALL your energy consumption you'll see similar data. Oh, of course, in mere math terms I can produce 110-130% of my overall consumption from the grid. BUT that's just math, it's not autonomy because it compute locally generated energy vs locally absorbed energy from the grid. Autonomy means you have to store or use ALL the energy you produce. Look at your self-consumed energy not the balance between what you give to the grid and what you get from it. To dig more: - try to measure how much energy you use for heating/cooling - how much for hot water - how much for cooking - how much for VMC if any - how much for the car You'll might be astonished about the result in mere kWh.
  - lostmsu 4y ago
    But most of the heating is the space heating, and heat pumps have way over 100% efficiency while gas burning is <100%
    - kkfx 4y ago
      Sure, but we still need heating. For instance the last days (-8℃ to 6℃) from 17:30 to 10:00 in the morning I need from 1 to 1.8kW constant power for main home heat pump and VMC small one. When the Sun shine I do not need heating, large glass surfaces on the south side get enough heat directly from the Sun, but from p.v. I have around 3 hours with enough power for doing useful things, like dishwasher, washing machine, hot water heater etc not more now and Sunny days are still very few compared to cloudy/rainy/snowy ones. In the coldest part of the winter (-25℃ to -3℃) sometimes I need 3kW just for heating. And even if not much used I also have to recharge my car witch eat around 60-70kWh/week. If you go northern, for instance when I was in south Sweden the home ALONE, witch was not super-new but still relatively new and well insulated, eat around 60kWh/day... Sure, from late May to September from the grid I consume VERY little, but as I said I live all the year, being unable to hibernate like bears...

by kkfx 4y ago

Ballas 4y ago

You should really do an energy audit to figure out why you are using so much power. There is likely a more optimal way of spending your money to optimize your energy requirements. I have 5kWp and that generates more than double my needs on average (albeit in an even more solar friendly location than you).

kkfx 4y ago
It's not that much power, it's simply the normal home needs: being a new home it's ALL electric, heating/cooling, cooking, hot water, ... if you have a classic home where for instance heating/cooling is not needed of course the story SEEMS different until you do a bit of conversion: - 1 standard m³ CH₄ is ~10.36kWh - LPG in standard m³ is ~12.80kWh in kg ~10.87kWh - 1kg of pellets ~4-5 kWh - 1 liter of heating oil (it's name vary from country to country, but it essentially diesel in the west) is ~11.1kWh - 1kg of reasonably dry coal is ~10 kWh Once you compute ALL your energy consumption you'll see similar data. Oh, of course, in mere math terms I can produce 110-130% of my overall consumption from the grid. BUT that's just math, it's not autonomy because it compute locally generated energy vs locally absorbed energy from the grid. Autonomy means you have to store or use ALL the energy you produce. Look at your self-consumed energy not the balance between what you give to the grid and what you get from it. To dig more: - try to measure how much energy you use for heating/cooling - how much for hot water - how much for cooking - how much for VMC if any - how much for the car You'll might be astonished about the result in mere kWh.
- lostmsu 4y ago
  But most of the heating is the space heating, and heat pumps have way over 100% efficiency while gas burning is <100%
  - kkfx 4y ago
    Sure, but we still need heating. For instance the last days (-8℃ to 6℃) from 17:30 to 10:00 in the morning I need from 1 to 1.8kW constant power for main home heat pump and VMC small one. When the Sun shine I do not need heating, large glass surfaces on the south side get enough heat directly from the Sun, but from p.v. I have around 3 hours with enough power for doing useful things, like dishwasher, washing machine, hot water heater etc not more now and Sunny days are still very few compared to cloudy/rainy/snowy ones. In the coldest part of the winter (-25℃ to -3℃) sometimes I need 3kW just for heating. And even if not much used I also have to recharge my car witch eat around 60-70kWh/week. If you go northern, for instance when I was in south Sweden the home ALONE, witch was not super-new but still relatively new and well insulated, eat around 60kWh/day... Sure, from late May to September from the grid I consume VERY little, but as I said I live all the year, being unable to hibernate like bears...