• silence7OPM
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    2 months ago

    It’s not just the upfront savings; it’s that it takes truly huge amounts of storage to deal with intermittency in one location. You need a lot less storage in the aggregate if you can move power from one location to another. This makes systems where almost everybody is connected cheaper for society as a whole.

    • Sonori@beehaw.org
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      2 months ago

      You need less on a social scale if everyone is interconnected obviously, but at the individual level it may well cost more. People were doing household scale off grid with a pile lead acid for decades after all.

      Households don’t necessarily need that much power, and while heat pumps change that up north in the winter, when it comes to modern day solar off grid you often use two to three times the inverting capacity worth of panel, precisely because it allows for reliable near full power generation on cloudy or snowy days.

      • silence7OPM
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        2 months ago

        I’ve lived with one of those systems:

        • it didn’t use the electricity for heating, cooling, refrigeration, water heating, or cooking
        • It was 12v electricity, so you had to have specialized lighting and other appliances to use it
        • you tended to have limited electricity available in the winter

        It’s not the same as the almost-always-available situation that people expect.

        • Sonori@beehaw.org
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          2 months ago

          So have I, and nowadays it very much is almost always available situation people expect, even for fully electrified homes. PV paneling cheaper per square m than fencepost plus being able to store a full weeks worth of average amarican home consumption for 20k of new battery have combined to make generatorless off grid a lot more practical.

          • silence7OPM
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            2 months ago

            Yes, if you’re not running HVAC in a northern climate. Those use enough electricity that grid-connection is incredibly valuable.

            • Sonori@beehaw.org
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              2 months ago

              Even then, modern heat pumps on average only use in the neighborhood of .5k to 2k kwh during the coldest months in southen Canada/ northern US, that is definitely within the capabilities of an reasonably affordable properly designed off grid solar system. Hence why I suggested it was reasonably doable for a fully electrified home, and will likely be much cheaper by the time your average lemmy user is building or buying their dream home.

              Currently such a system is already in the cost range of twice that of a inground pool, by far the two most expensive parts of it, overpanneling and battery storage are plummeting in cost.

              • silence7OPM
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                2 months ago

                I think you underestimate what it takes to heat an older structure in the north. 7kw is pretty common for whole-home retrofits. Enough to run that all night in winter during an extended cloudy spell means a lot more panels and a lot more storage.

                • Sonori@beehaw.org
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                  2 months ago

                  Are you suggesting a 7kw heat pump, or 7,000kwh/m highest hearing load? Because the former would already come out to about 2.5k kwh assuming a 12h duty cycle for 30 days, while the latter would cost over a thousand dollars a month to run at average US electricity prices during the month of highest load.

                  For reference the typical heat pump in the typical amarican single family house consumes 5.4k kwh in an entire year.

                  • silence7OPM
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                    2 months ago

                    the typical heat pump in the typical amarican single family house consumes 5.4k kwh in an entire year.

                    I think you googled, took the first result, which was:

                    https://www.energysage.com/electricity/house-watts/how-many-watts-does-an-air-source-heat-pump-use/

                    and it says “Based on an EnergySage analysis of a Department of Energy database, a typical heat pump in a typical home uses 5,475 kilowatt hours (kWh) per year”

                    but then treated it as meaning a “about 5½kwh” instead of 5475kwh.

                    The two are very different numbers, and most heat pumps in the US are currently installed in warmer locations, so you can expect utilization in colder places to be appreciably higher.

                    A heat pump won’t be running at peak output all year long, but during winter in the north, it’s likely to do so every night for a week at some point.

                    A $1000/month heating bill isn’t that rare in some parts of the US in winter.