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You're assuming that the capacity of the Powerwall is all the power available. With a solar-tied backup system, there is power coming in from the modules as we

You're assuming that the capacity of the Powerwall is all the power available. With a solar-tied backup system, there is power coming in from the modules as well which is additive to the discharge rate of the Powerwall if wired correctly. So even your massive A/C should be useable for a while during daylight hours if your solar system is large enough. Most people here in humid hurricane country opt to have a 15 amp 120v window unit available instead, and limit themselves to a single comfortable room.

dragontamer 10y ago
> You're assuming that the capacity of the Powerwall is all the power available. With a solar-tied backup system, there is power coming in from the modules as well which is additive to the discharge rate of the Powerwall if wired correctly. That still begs the question: why use Solar + Powerwall when Solar + Gas Generator has higher capacity and is cheaper? > 15 amp 120v window unit 1800 W, which is more than half the capacity of your Powerwall. Not enough electricity left over to run a single-room AC and a dishwasher at night. Got an electric oven or stovetop? 4000W or so? Yeah, Powerwall just ain't gonna cut it. 3.3kW capacity is just way too small for the typical house. The answer to backup is frankly Solar + Generator. Battery backup just doesn't have the specs or the price to be practical yet.
- wang_li 10y ago
  > why use Solar + Powerwall when Solar + Gas Generator has higher capacity and is cheaper? Because Elon Musk! Senpai notice me!
- brightball 10y ago
  Y'all have thoroughly convinced me to disregard Powerwalls :)
- jakub_h 10y ago
  Or, solar+battery+generator for uninterruped power while still keeping costs low compared to a large battery?
  - dragontamer 10y ago
    What does the battery accomplish? I mean, maybe an UPS for your computer if you're running something mission critical? Something that can last for 20 minutes while the generator boots up? But I don't think most people are running mission-critical programs at home.
    - jakub_h 10y ago
      In my home, a single Powerwall battery could cover 90+ percent (or perhaps 95+ percent?) of nights even in an off-grid arrangement. Covering the rare extremes with a $150 generator would be more cost-efficient than using a larger battery, and likewise, covering the usual case with a battery would be more cost-efficient than running all nights inefficiently using our $5/USgal gasoline.
      - dragontamer 10y ago
        Why go off-grid when Net-Metering exists?

dragontamer 10y ago

> You're assuming that the capacity of the Powerwall is all the power available. With a solar-tied backup system, there is power coming in from the modules as well which is additive to the discharge rate of the Powerwall if wired correctly. That still begs the question: why use Solar + Powerwall when Solar + Gas Generator has higher capacity and is cheaper? > 15 amp 120v window unit 1800 W, which is more than half the capacity of your Powerwall. Not enough electricity left over to run a single-room AC and a dishwasher at night. Got an electric oven or stovetop? 4000W or so? Yeah, Powerwall just ain't gonna cut it. 3.3kW capacity is just way too small for the typical house. The answer to backup is frankly Solar + Generator. Battery backup just doesn't have the specs or the price to be practical yet.

wang_li 10y ago
> why use Solar + Powerwall when Solar + Gas Generator has higher capacity and is cheaper? Because Elon Musk! Senpai notice me!
brightball 10y ago
Y'all have thoroughly convinced me to disregard Powerwalls :)
jakub_h 10y ago
Or, solar+battery+generator for uninterruped power while still keeping costs low compared to a large battery?
- dragontamer 10y ago
  What does the battery accomplish? I mean, maybe an UPS for your computer if you're running something mission critical? Something that can last for 20 minutes while the generator boots up? But I don't think most people are running mission-critical programs at home.
  - jakub_h 10y ago
    In my home, a single Powerwall battery could cover 90+ percent (or perhaps 95+ percent?) of nights even in an off-grid arrangement. Covering the rare extremes with a $150 generator would be more cost-efficient than using a larger battery, and likewise, covering the usual case with a battery would be more cost-efficient than running all nights inefficiently using our $5/USgal gasoline.
    - dragontamer 10y ago
      Why go off-grid when Net-Metering exists?