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Unfortunately this article (like most news articles seem to) mixes up kW and kWh, so we don't actually know how big his off grid solar system is. I'm guessing 8

Unfortunately this article (like most news articles seem to) mixes up kW and kWh, so we don't actually know how big his off grid solar system is. I'm guessing 8 kW (or 8 kWh per hour, without capacity factor taken into account). It's a pretty compelling option - spend less than the connection fee to get free electricity. The biggest problem is that you have to size your system for cloudiest days in the dead of winter - which means massive batteries and lots of extra panels. It would be interesting to see a full cost breakdown for a realistic use case over 4 or 5 years, including the cost of maintenance. I imagine you could throw a $1000 generator into the mix to cover the really bad days, but then that's an added maintenance burden.

giantg2 5y ago
If you're able to run central air plus a bunch of other stuff at the same time, then I would think your assumption of 8kW is right. If capacity was only 8kWh, then they could only run all this stuff for maybe 1-2 hours a day. That seems like an absurd outcome, and unlikely.
- Filligree 5y ago
  > If capacity was only 8kWh, then they could only run all this stuff for maybe 1-2 hours a day. I think the correct reading is they'd be able to run it for 1-2 hours, once. Presumably it's all powered off a bank of AA batteries. ;-)
  - jacquesm 5y ago
    He's using some pretty heavy duty prismatic Lithium Ion cells.
    - Filligree 5y ago
      Then presumably it's 8 kW. I wonder what the base rating of the solar panels is; it might be 60-70 kW. (If it's just the panels shown in the photo, then those are probably 8kW on a sunny day.)
      - jacquesm 5y ago
        26 panels at 300 W / panel is indeed about 7.8KW with some leeway if it is cold they will do a bit better and when it's warm they'll do a bit worse. Rural Canada is quite far North, so your sunlight will not quite reach the 1KW/square meter that you can expect elsewhere due to the longer path the light needs to take through the atmosphere which causes some attenuation.
- jacquesm 5y ago
  Why is that unlikely? You don't need all that much power if you're frugal and the first thing any person building a renewables installation is going to buy is a kill-a-watt, the next thing will be an energy efficient fridge. It's amazing how much you can shave off your electricity usage if you start monitoring where it goes. Converting electricity to heat is a bit like turning the best steak into hamburger, wasteful and costly. Electric heat is pretty much limited to the United States, in most other countries power is way too expensive to be used for heating.
  - giantg2 5y ago
    It's unlikely because central AC units (they mention having one) tend to be energy hogs.
    - jacquesm 5y ago
      Central AC is pretty much incompatible with having an off-grid system. But there are good alternatives such as heatpumps and running your central heat (water based) in reverse to cool.
      - giantg2 5y ago
        Well the article says their system runs central AC. That's why I'm thinking that it would use the bulk of the electricity.
        jacquesm 5y ago
        Yes, that's why they have an oversized system, essentially they are putting in roughly twice the amount of power they need so that they can convert sunlight into electricity to power an AC that then moves about half of that in heat. It would be far more efficient to use a heatpump.
        giantg2 5y ago
        I'm not sure what you mean by using a heat pump for AC. AC is effectively a heat pump. Colloquially, we call HVAC systems that use a heat pump to heat the house as a "heat pump", while a heat pump used to cool the house (heat the outside) is called air conditioning. Many AC systems are also configured to heat the house (heat pump can work in either direction). Why do you say it's an oversized system? It seems like it is sized appropriately give the stuff it is required to run.
jacquesm 5y ago
Capacity factor of a renewables system is usually around 20 to 30%.
Filligree 5y ago
Better throw in a backup generator for the backup generator, as well. They're mechanical devices, and fail a lot. Solar panels typically produce 10-15% of their normal power if it's cloudy. Adding a wind turbine or two can do a lot to make up for that, but then there's winter... I'd very much like to see what their thoughts are in a year.
- MaKey 5y ago
  Adding a small wind turbine is usually not worth it. They need a lot of wind to produce any meaningful energy output while costing a few thousand $. So unless you go really big, you'd be better off adding more solar panels.
boringg 5y ago
>> It's a pretty compelling option - spend less than the connection fee to get free electricity. The biggest problem is that you have to size your system for cloudiest days in the dead of winter - which means massive batteries and lots of extra panels. Or alternatively have a manageable demand side so you can minimize your demand on bad weather days. Definitely 8KW system - everyone messes up kW and kWh.

giantg2 5y ago

If you're able to run central air plus a bunch of other stuff at the same time, then I would think your assumption of 8kW is right. If capacity was only 8kWh, then they could only run all this stuff for maybe 1-2 hours a day. That seems like an absurd outcome, and unlikely.

Filligree 5y ago
> If capacity was only 8kWh, then they could only run all this stuff for maybe 1-2 hours a day. I think the correct reading is they'd be able to run it for 1-2 hours, once. Presumably it's all powered off a bank of AA batteries. ;-)
- jacquesm 5y ago
  He's using some pretty heavy duty prismatic Lithium Ion cells.
  - Filligree 5y ago
    Then presumably it's 8 kW. I wonder what the base rating of the solar panels is; it might be 60-70 kW. (If it's just the panels shown in the photo, then those are probably 8kW on a sunny day.)
    - jacquesm 5y ago
      26 panels at 300 W / panel is indeed about 7.8KW with some leeway if it is cold they will do a bit better and when it's warm they'll do a bit worse. Rural Canada is quite far North, so your sunlight will not quite reach the 1KW/square meter that you can expect elsewhere due to the longer path the light needs to take through the atmosphere which causes some attenuation.
jacquesm 5y ago
Why is that unlikely? You don't need all that much power if you're frugal and the first thing any person building a renewables installation is going to buy is a kill-a-watt, the next thing will be an energy efficient fridge. It's amazing how much you can shave off your electricity usage if you start monitoring where it goes. Converting electricity to heat is a bit like turning the best steak into hamburger, wasteful and costly. Electric heat is pretty much limited to the United States, in most other countries power is way too expensive to be used for heating.
- giantg2 5y ago
  It's unlikely because central AC units (they mention having one) tend to be energy hogs.
  - jacquesm 5y ago
    Central AC is pretty much incompatible with having an off-grid system. But there are good alternatives such as heatpumps and running your central heat (water based) in reverse to cool.
    - giantg2 5y ago
      Well the article says their system runs central AC. That's why I'm thinking that it would use the bulk of the electricity.
      - jacquesm 5y ago
        Yes, that's why they have an oversized system, essentially they are putting in roughly twice the amount of power they need so that they can convert sunlight into electricity to power an AC that then moves about half of that in heat. It would be far more efficient to use a heatpump.
        giantg2 5y ago
        I'm not sure what you mean by using a heat pump for AC. AC is effectively a heat pump. Colloquially, we call HVAC systems that use a heat pump to heat the house as a "heat pump", while a heat pump used to cool the house (heat the outside) is called air conditioning. Many AC systems are also configured to heat the house (heat pump can work in either direction). Why do you say it's an oversized system? It seems like it is sized appropriately give the stuff it is required to run.

jacquesm 5y ago

Capacity factor of a renewables system is usually around 20 to 30%.

Filligree 5y ago

Better throw in a backup generator for the backup generator, as well. They're mechanical devices, and fail a lot. Solar panels typically produce 10-15% of their normal power if it's cloudy. Adding a wind turbine or two can do a lot to make up for that, but then there's winter... I'd very much like to see what their thoughts are in a year.

MaKey 5y ago
Adding a small wind turbine is usually not worth it. They need a lot of wind to produce any meaningful energy output while costing a few thousand $. So unless you go really big, you'd be better off adding more solar panels.

boringg 5y ago

>> It's a pretty compelling option - spend less than the connection fee to get free electricity. The biggest problem is that you have to size your system for cloudiest days in the dead of winter - which means massive batteries and lots of extra panels. Or alternatively have a manageable demand side so you can minimize your demand on bad weather days. Definitely 8KW system - everyone messes up kW and kWh.