diy solar

diy solar

Recent content by kbridgeman

  1. K

    SMA Sunny Island grid-tie / battery backup with Sunny Boy inverters design discussion

    Yes on the Midnight SPDs. We are on a new page ... so thank you again for your patience and detailed explanations. I've reread the thread at least 10 times. No telling what I haven't yet absorbed though. ;)
  2. K

    SMA Sunny Island grid-tie / battery backup with Sunny Boy inverters design discussion

    Added interlock breaker. > Don't want to get distracted with this right now. But, once I have the base design I'm considering adding the Midnight Solar AC Panel which provides a 60amp bypass from the PV input to the main panel if SI is down. I suppose the interlocked breaker backfeed from...
  3. K

    SMA Sunny Island grid-tie / battery backup with Sunny Boy inverters design discussion

    Focusing on the breakers, I simplified the diagram per this post and another that referenced the 70A main breaker. 70A in the main panel to SIs 56A in the PV landing panel to/from SI. 32A breaker (25A max output) for each SB 6.0 ... will change if I go with the 7.7 (40A breaker for 32A max...
  4. K

    SMA Sunny Island grid-tie / battery backup with Sunny Boy inverters design discussion

    @Hedges, I'm confused about 3 strings; i.e. 3 MPPT. Seems to me I get to maximum wattage with only 2 strings, so really unsure how or why 3 strings would be leveraged. Unless we are thinking 2 of the strings are at 90' different orientation so only 2 highly active at any one time. The...
  5. K

    inverters to work with positive ground panel array

    x sorry jumped on wrong thread. can't figure how to delete.
  6. K

    SMA Sunny Island grid-tie / battery backup with Sunny Boy inverters design discussion

    yes, @Hedges and I discussed. I subsequently saw this (see JPG) from: that helps further clarify. Basically, if grid-tied should have 1W SB for 1W of Sunny Island. I wasn't clear above, the sizing was for the AC-1 (island) side so I'm going for 1:1 on wattage. so, with 2 SI, I will have 2...
  7. K

    SMA Sunny Island grid-tie / battery backup with Sunny Boy inverters design discussion

    @Hedges @MurphyGuy String sizing validation. Sunny Boy 6.0 - 3 MPPT - 10a/mppt - 100-550V operating voltage - 600V max Not committed to this, just using it as an exercise: JA Solar 410 W 40.87 VOC 18x ~410W 41 V 9s x 2 - I didn't write 2p here because each string will go into a separate MPPT...
  8. K

    SMA Sunny Island grid-tie / battery backup with Sunny Boy inverters design discussion

    Agree with your point on price. What if I said I was going to buy the equipment right away, but still was going to approach the build incrementally? Thoughts on that as an approach?
  9. K

    SMA Sunny Island grid-tie / battery backup with Sunny Boy inverters design discussion

    ah, you are right. Can use the SI as battery backup with 1 but need an auto transformer to use SB. Score 1 for you, thanks.
  10. K

    SMA Sunny Island grid-tie / battery backup with Sunny Boy inverters design discussion

    @Hedges @MurphyGuy - When I lead software development projects I'm very good at breaking down a project into achievable units and iterating so that we can both show traction and successes as well as reduce risk to a big bang deliverable. Therefore, my inclination is to do the same with this...
  11. K

    SMA Sunny Island grid-tie / battery backup with Sunny Boy inverters design discussion

    Ah jeez, no idea what I’ve been looking at , but with fresh eyes there’s a plethora of info I must have looked right past. Thx. Reading TFM. ??‍♂️
  12. K

    SMA Sunny Island grid-tie / battery backup with Sunny Boy inverters design discussion

    I cannot find where you get 12kw SI (2x6048) can manage 24kW SB. Here's the Sunny Island datasheet. https://files.sma.de/downloads/SI6048US-DS-en-28.pdf?_ga=2.6202801.344650644.1647641451-782371609.1647173240
  13. K

    SMA Sunny Island grid-tie / battery backup with Sunny Boy inverters design discussion

    @Hedges - Really embarrassing question, but if I have 2 Square D 40MW225 panels with 200 amp main breaker, does that mean I have 400 amps coming into the house? The one panel does not feed the other. They both come from the meter.
  14. K

    SMA Sunny Island grid-tie / battery backup with Sunny Boy inverters design discussion

    I was EECS or EECE (computer engineering) also; University of Illinoi '86/87 with EECS Masters in Artificial Intelligence (useless) '89.
  15. K

    SMA Sunny Island grid-tie / battery backup with Sunny Boy inverters design discussion

    ah, might not know what I'm talking about....should have said 200a panel breaker. No idea on the busbar. Will have to figure that out. I do have a Square D panel 40MW225. So, I'm guessing that means 225a bus bar. Actually, I have two 40MW225s. Truly embarrassing that I have an electrical...
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