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That's fair. Better comparison: Author's config: 3x Powerwalls + inverters = 40 kWh 4.2 kW array £39,360 = $53k USD Alternative: EG4 18kPV Hybrid Inverte

by mbesto 9mo ago

That's fair. Better comparison: Author's config: 3x Powerwalls + inverters = 40 kWh 4.2 kW array £39,360 = $53k USD Alternative: EG4 18kPV Hybrid Inverter = $5000 3x RIUXU = $9600 10x Trina Solar 435w panels = $1580 Cabling, installations, etc. = $5000 Total = $21k It's not even close...

pchew 9mo ago
This is still not an accurate comparison. I'm not a Tesla fanboy but of all of the major players in the non-diy game (Enphase, Franklin, Tesla, Sol-Ark) they provide the best value for money, and are impressive pieces of equipment. The EG4 18k has 11.5 kw backfeed capability, with a rather pathetic 65ish amp in-rush. Obviously 18kw usable solar capacity(they technically let you land up to 21kw, but only 18 is usable). The Powerwall system you outlined can take 60kw of usable solar input, has 34kw standing backfeed capability, and a whopping 555 amp in-rush (not a typo, it's 185 amps per unit). Not to get in to warranties, etc.
- mbesto 9mo ago
  None of those things matter when your solar array is 4.5 kW and you have a standard 150A/200A grid in.... Like I said, they basically are not sold to scale like a normal household uses electricity. EDIT: What the heck is in-rush and backfeed? Are you talking about AC input to charge the batteries? The 18k is 50A @ 240VAC (12kW) fyi. Also, why does the charge rate even matter there? For the AC output its also 12 kW...the family is average 48 kWh days, which is 2 kW hourly average...
  - labcomputer 9mo ago
    Inrush is surge capacity. Starting a big motor like an air conditioner can require 2x or 3x the continuous running amps, but only for a few seconds.
  - pchew 9mo ago
    Inrush is exactly what it says it is, it's inrush current. When you have a sudden surge on something, that's inrush. Lots of appliances in your home have a large inrush, much larger than the breaker they're on. Inrush happens faster than a breaker trips, which doesn't matter when you're on the grid and the inrush is lower than your mainbreaker, it matters when you have an inverter in the way with a passthrough limit and an inrush limit. Typical central HVAC units have LRA over 100 amps. If we're talking about 'doesn't even matter with a 4kw array' well, hell, how the hell you gonna charge ~40kwh of battery with solar array that nominally produces 20kwh a day on its best day, assuming all conditions are perfect? Backfeed is what the inverter can push out from the battery to the home. It's the size of the tube coming from the gallons of water reservoir. EG4 18k has a tiny tube, no matter how much battery you put on it. Like emptying a 50 gallon drum with a drinking straw(and with the 4kw array, filling it with a 12 oz cup).
    - mbesto 9mo ago
      > Inrush is exactly what it says it is, it's inrush current These are not terms commonly used in the industry, thanks for the clarification. > Lots of appliances in your home have a large inrush, much larger than the breaker they're on. And inverters are designed to compensate for short term surges too fyi. The 18k provides 65A for a few seconds as an example. > well, hell, how the hell you gonna charge ~40kwh of battery with solar array that nominally produces 20kwh a day on its best day, assuming all conditions are perfect? Because you can't and don't need to...you should be asking the author of the original post, because they do what pretty much every other grid tied system which is that you pass through the power from the grid. > Backfeed is what the inverter can push out from the battery to the home. https://www.wartsila.com/encyclopedia/term/backfeeding https://www.wartsila.com/encyclopedia/term/backfeeding huh? > It's the size of the tube coming from the gallons of water reservoir. EG4 18k has a tiny tube, no matter how much battery you put on it. 1. The 18k can push 50A on each leg and most residential are sized at 150a or 200A, which are ridiculously oversized, so at most, even with two EVs and a 4 ton AC running in Texas, I max out at 150A. I can put 3 18k's in parallel if I really want to and its STILL cheaper than a powerwall battery/inverter combo. 2. There is no reason to have a "pipe" so large that it only is used for less than 5% of the overall runtime. This is why the powerwall setup doesnt make any sense.

by mbesto 9mo ago

pchew 9mo ago

This is still not an accurate comparison. I'm not a Tesla fanboy but of all of the major players in the non-diy game (Enphase, Franklin, Tesla, Sol-Ark) they provide the best value for money, and are impressive pieces of equipment. The EG4 18k has 11.5 kw backfeed capability, with a rather pathetic 65ish amp in-rush. Obviously 18kw usable solar capacity(they technically let you land up to 21kw, but only 18 is usable). The Powerwall system you outlined can take 60kw of usable solar input, has 34kw standing backfeed capability, and a whopping 555 amp in-rush (not a typo, it's 185 amps per unit). Not to get in to warranties, etc.

mbesto 9mo ago
None of those things matter when your solar array is 4.5 kW and you have a standard 150A/200A grid in.... Like I said, they basically are not sold to scale like a normal household uses electricity. EDIT: What the heck is in-rush and backfeed? Are you talking about AC input to charge the batteries? The 18k is 50A @ 240VAC (12kW) fyi. Also, why does the charge rate even matter there? For the AC output its also 12 kW...the family is average 48 kWh days, which is 2 kW hourly average...
- labcomputer 9mo ago
  Inrush is surge capacity. Starting a big motor like an air conditioner can require 2x or 3x the continuous running amps, but only for a few seconds.
- pchew 9mo ago
  Inrush is exactly what it says it is, it's inrush current. When you have a sudden surge on something, that's inrush. Lots of appliances in your home have a large inrush, much larger than the breaker they're on. Inrush happens faster than a breaker trips, which doesn't matter when you're on the grid and the inrush is lower than your mainbreaker, it matters when you have an inverter in the way with a passthrough limit and an inrush limit. Typical central HVAC units have LRA over 100 amps. If we're talking about 'doesn't even matter with a 4kw array' well, hell, how the hell you gonna charge ~40kwh of battery with solar array that nominally produces 20kwh a day on its best day, assuming all conditions are perfect? Backfeed is what the inverter can push out from the battery to the home. It's the size of the tube coming from the gallons of water reservoir. EG4 18k has a tiny tube, no matter how much battery you put on it. Like emptying a 50 gallon drum with a drinking straw(and with the 4kw array, filling it with a 12 oz cup).
  - mbesto 9mo ago
    > Inrush is exactly what it says it is, it's inrush current These are not terms commonly used in the industry, thanks for the clarification. > Lots of appliances in your home have a large inrush, much larger than the breaker they're on. And inverters are designed to compensate for short term surges too fyi. The 18k provides 65A for a few seconds as an example. > well, hell, how the hell you gonna charge ~40kwh of battery with solar array that nominally produces 20kwh a day on its best day, assuming all conditions are perfect? Because you can't and don't need to...you should be asking the author of the original post, because they do what pretty much every other grid tied system which is that you pass through the power from the grid. > Backfeed is what the inverter can push out from the battery to the home. https://www.wartsila.com/encyclopedia/term/backfeeding https://www.wartsila.com/encyclopedia/term/backfeeding huh? > It's the size of the tube coming from the gallons of water reservoir. EG4 18k has a tiny tube, no matter how much battery you put on it. 1. The 18k can push 50A on each leg and most residential are sized at 150a or 200A, which are ridiculously oversized, so at most, even with two EVs and a 4 ton AC running in Texas, I max out at 150A. I can put 3 18k's in parallel if I really want to and its STILL cheaper than a powerwall battery/inverter combo. 2. There is no reason to have a "pipe" so large that it only is used for less than 5% of the overall runtime. This is why the powerwall setup doesnt make any sense.