Impressions from Intersolar 2017

bill von novakbill von novak Solar Expert Posts: 706 ✭✭✭✭

Thought I would relate some impressions from the Intersolar show I attended yesterday in SFO.  

General impressions - storage is exploding.  There were at least a dozen battery/inverter combos there intended for use with solar, and almost all inverter companies now have battery-backed options.  It’s too bad that we stopped the Ezero program – there’s a big need out there for systems that coordinate battery based systems to manage peak shaving/load shifting.

Solaredge has a combination EV charger and grid tie inverter.  Nothing too special about that.  But one cool thing is that when it is installed on a 40A breaker (which is limited to 32A during normal operation) the EV charger will actually go to 40A when the solar system is running, since it can still draw 32 amps or less through the breaker.  

Solaredge also has a 400V storage system that they pair with an LG battery.  They have sold a few of these so far.

 Pika had a very interesting islanding inverter in 7600w and 11400w flavors. They use a 380V DC bus system (called the REbus) - the inverter is intended to be the central device in such a system.  They DC bus is intended to run to solar and battery locations. So far they only have inverter plus storage plus solar but other companies (like that chiller company) are using the DC directly.  This is something that is long overdue IMO - it's silly to convert the 300-500 volt solar input down to 48 volts for batteries, then back up to 240VAC.  By keeping most of the system at the higher voltage, wiring cost is reduced, breaker size (and cost) is reduced and the power is more usable overall.  Most large motor drives prefer DC, and EV's definitely prefer DC.

 Pika's battery solution uses 48V Panasonic lithium ion modules and comes in 10kWhr or 15kWhr flavors.

 Pika's solar interface is a peak power tracker that takes in solar power up to 420V/2500W and then outputs it to the REbus (380V).  MPPT range is 60-360V; full power range is 200-360V.

 Saw two panel cleaning robots and one cleaning thing that looks like a backhoe with a big car-wash brush on the front.

 Interphase has a "storage chiller" that connects to the REbus (380VDC) and use the ~10 ton chiller to make ice.  Then they run air conditioning off the ice.  It's intended for peak shaving/load shifting - make ice at night when it's cool and power is cheap, then use it when it's hot out.  EER is 26.5.

 Ensync matrix energy management also uses a 400VDC system to connect batteries, solar, inverters, motor drives - but does not expose the voltage outside their box.  They said they were thinking about making it available outside.  They also have a 600V in/400V out charge controller.

 Midnite Solar has their new modular inverter.  Each rack has five bays - two for charge controllers and three for inverters.  It looks like the charge controllers can go to 100A out / 600 volts in which is very nice.  You can expand it up to 4 racks.  Uses a 48 volt battery system.

 Midnite also is announcing a 4000 watt 12/24/28 volt inverter that is rated to UL1741 - which should mean it can feed back to the grid.  This would be the first 12V inverter capable of doing that that I have seen.

 Aurora PV system planning SW - this is a nice solar planning package that lets you take a Google Maps picture of your home, place panels and see how much power you will get. aurorasolar.com

 Darfon makes a hybrid inverter (H5000) which will do self-consumption, peak shifting, peak shaving etc. www.darfonsolar.com  It has a MPPT charge controller that works to 500V.  They also have the H300 5kwhr lipo battery.

 Eterbright makes CIGS panels (thin film) that are above 15% efficiency now.  Their 3600A1 is a 360W 15.4% efficiency panel.  (But will it last?)

 Solar panels:

  • JPS-300M-60 Japan Solar 18.35%
  • Talesun Hipro M350+ panels - 72c 18%
  • Seraphim 72C 360W panel - SRP-6MA - 18.6% eff - 1966x992mm
  • BolySolar makes a non-tracking concentrator.  Panel efficiencies of 20%+.   www.bolymedia.com
  • Sunspark panels 300W sunsparkusa.com 18.2%eff SST-300W - made in USA!
  • LG Neon panels now come with integrated microinverters

HarvestHP combines solar-PV and solar thermal.  I think it will only work for low temp (pool) applications tho.

A company called BizLink does fused MC4 Y cables.  Less need for junction boxes on the roof!

 

Batteries:

  • At least three companies (BYD, AES and a third one) were offering these massive cargo container batteries - 2MWhr, 4MW max power.
  • Siemens and AES just teamed up to do more grid scale battery power.
  • SimpliPhi has a 3.4kWhr 48V battery for sale now. Light enough to lift yourself.  Also a Conext XW+ based storage system.
  • Trojan is now making AGM batteries just for solar - SAGM-06 220/315/375 ah
  • Mercedes Benz has 2.5 to 20kw storage systems. They also have larger systems that are made of old car batteries (from their EV's.)  Interesting.
  • Elite power solutions (elitepowersolutions.com) does 48 volt battery systems with BMSes built in.
  • Reli3on has a 48V 300AH li-ion battery.  (15KW)

 

Del Sol has plastic shingles with embedded crystalline PV for about $2.80 a watt.  Specs are 17W, 3.10V/5.5A peak power.  It's intended for string inverters so you have to series about 100 of these to get a string.

 Aenergy / Aplus has standing-seam solar roof panels (i.e. they replace ordinary standing-seam roof panels.)  About $1.50 a watt.  Each panel is 75W (18.7V 8A pk) so you'd have to series 4 to get an "ordinary" 72 cell panel, or 20 or so to get a string for an inverter.

 Nuvation has a simple/small low voltage BMS for 16S batteries, up to 60V.

 bayo0s.com makes massive eight foot long ground screws, which are pretty cool.  They take a golf cart sized power driver to get them into the dirt, but once they are in you can build things (like groundmount solar systems) right on top of the screws.  They probably wouldn't work in the "dirt" here though; I usually need a prybar to get through at all.

 Cy solar has a cool mounting system for spanish tile.  You remove one tile, put one of these "fake" tiles back in (aluminim) and it has a mount on it.

 YM tech makes HVDC relays for EV's - www.goodymt.com - 15 to 600a - to 95V.  Good for battery disconnects for residential systems.

 

 

 

 




Comments

  • ThomThom Solar Expert Posts: 169 ✭✭✭
    Thanks fir the info

    thom
    Off grid since 1984. 430w of panel, 300w suresine , 4 gc batteries 12v system, Rogue mpt3024 charge controller , air breeze windmill, Mikita 2400w generator
  • AguarancherAguarancher Solar Expert Posts: 266 ✭✭✭
    edited July 12 #3
    Thanks...Excellent write up, better than crib notes..lol
  • SolraySolray Registered Users Posts: 246 ✭✭
    > @bill von novak said:
    >
    >
    >  Midnite
    > also is announcing a 4000 watt 12/24/28 volt inverter that is rated to UL1741 -
    > which should mean it can feed back to the grid.  This would be the first
    > 12V inverter capable of doing that that I have seen.
    >  

    What is the point of a 28 volt input inverter?
    Is 28 volts common somewhere?
  • ThomThom Solar Expert Posts: 169 ✭✭✭
    I think it's 48v  not 28 misprint 
    Off grid since 1984. 430w of panel, 300w suresine , 4 gc batteries 12v system, Rogue mpt3024 charge controller , air breeze windmill, Mikita 2400w generator
  • MangasMangas Solar Expert Posts: 537 ✭✭✭✭
    Thank you!
    Ranch Off Grid System: 2 x pair stacked Schneider XW 5548+ Plus inverters (4), 2 x Schneider MPPT 80-600 Charge Controllers, 2 Xanbus AGS Generator Start and Air Extraction System Controllers, 64 Trojan L16 REB 6v 375 AH Flooded Cel Batteries w/Water Miser Caps, 44 x 185 Sharp Solar Panels, Cummins Onan RS20 KW Propane Water Cooled Genset, ICF House Construction, 2 x High Efficiency Variable Speed three ton Central A/C 220v compressors, 2 x Variable Speed Air Handlers, 2 x HD WiFi HVAC Zoned System Controllers
  • MangasMangas Solar Expert Posts: 537 ✭✭✭✭
    edited July 13 #7
    The SAGM 06 375 look really interesting but pricey.

    Assume the XWs' and CC will manage.
    Ranch Off Grid System: 2 x pair stacked Schneider XW 5548+ Plus inverters (4), 2 x Schneider MPPT 80-600 Charge Controllers, 2 Xanbus AGS Generator Start and Air Extraction System Controllers, 64 Trojan L16 REB 6v 375 AH Flooded Cel Batteries w/Water Miser Caps, 44 x 185 Sharp Solar Panels, Cummins Onan RS20 KW Propane Water Cooled Genset, ICF House Construction, 2 x High Efficiency Variable Speed three ton Central A/C 220v compressors, 2 x Variable Speed Air Handlers, 2 x HD WiFi HVAC Zoned System Controllers
  • jonrjonr Solar Expert Posts: 858 ✭✭✭✭
    I agree about the new Trojan AGM batteries.  Slightly better life than flooded, but not by enough to make them cost effective.  So you have to value the other attributes of AGM (no watering, no gases, faster charging, etc).  
  • VicVic Solar Expert Posts: 2,815 ✭✭✭✭
    edited July 13 #9

    Thanks Bill for the very complete summary of the show.

    Was only able to spend a few hours there on Wednesday,   and cannot get back there today,  so your summary is quite helpful.

    It was very nice to spend time with the folks at MidNite Solar,   and some time at Magnum Energy as well.

    YES  the 4 kW MidNite inverter is planned to be a 12/24/48 V Inverter/Charger.   IIRC,  it will be 2.8 kW when on 12 V.

    Attached a pic of the MN 4 kW inverter,  that is in development.

    Bill,   Thanks again.     Vic

    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
  • PhotowhitPhotowhit Solar Expert Posts: 4,253 ✭✭✭✭

     Midnite also is announcing a 4000 watt 12/24/28 volt inverter that is rated to UL1741 - which should mean it can feed back to the grid.  This would be the first 12V inverter capable of doing that that I have seen.


    Not sure why a UL 1741 would mean it could back feed the grid.  Many/most can't.

    Actually am disappointed they would make a 4000 watt inverter that would run at 12 volts. If it will accept multiple voltages that's another story! I do like the idea of a cross voltage inverter. It will allow people more flexibility to buy one inverter and 'grow' a system. Heck I would be an interested buyer as I'm waiting for a battery to die to switch and buy a large enough inverter to properly run my home. 24 to 48...
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, ForkLift battery. Off grid for @13 of last 14 years. 1000 watts being added to current CC, @2700 watts to be added with an additional CC.
  • MarkCMarkC Solar Expert Posts: 155 ✭✭✭
    Bill;
    Very helpful summary.  You've got me motivated to check out (more local to Houston,TX, if any!) these conferences and try to attend.  Thanks.

    Does it appear to you that there are manufacturers - Ensync matrix energy management or Solaredge/others - interested in providing solar based (MPPT functionality) charger/controllers based on "quick charge - DC" protocols for electric vehicles?  This would require the standard CHAdeMO/CCS/Tesla connection equipment options to their DC charger/controllers.  I believe Setec Power has advertised they can provide these options (at least CHAdeMO and CCS), however their technical support is very lacking - not sure I want to risk a purchase.  

    I reviewed the presentation titles/synopses and did not see much focus on EVs and associated battery storage capabilities (except tours of Tesla!).  Did I miss something - is that not an active focus of this show?

    Appreciate your taking the time and effort,
    Mark
    3850 watts - 14 - 275SW SolarWorld Panels, 4000 TL-US SMA Sunny Boy Grid tied inverter.  2760 Watts - 8 - 345XL Solar World Panels, 3000 TL-US SMA Sunny Boy GT inverter.   3000 watts SMA/SPS power.  PV "switchable" to MidNite Classic 250ks based charging of Golf cart + spare battery array of 8 - 155 AH 12V Trojans with an  APC SMT3000 - 48 volt DC=>120 Volt AC inverter for emergency off-grid.   Also, "PriUPS" backup generator with APC SURT6000/SURT003  => 192 volt DC/240 volt split phase AC inverter.  
  • Dave AngeliniDave Angelini Solar Expert Posts: 3,304 ✭✭✭✭
    Outback also slipped the Skybox from about now to early 2018.
     Schneider is getting farther on the Bridge and some of the suppliers are training. I did training on the 400V LG RESU and I suppose if you have an electric car it might be nice but at 220 pounds I will not be anywhere near it. The 165 pound  Resu10 @ 48 is at my limit.

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     http://members.sti.net/offgridsolar/
    E-mail offgridsolar@sti.net

  • MarcFMarcF Registered Users Posts: 4
    Thanks for your report of InterSolar SF 2017 Bill.  I attended the show myself, but didn't have time for a deep dive at every booth of interest.
    I am intrigued about the prospect of the SolarEdge Inverter with integrated EV charger.  While it doesn't seem like a breakthrough, as a residential solar PV installer who is constantly challenged to find breaker space for both a PV breaker AND and EV charging breaker in the service panel, if this can reduce the need to 1 single circuit breaker for both, that is HUGE in my book.  I look forward to learning more about this product.

    As far as the InterSolar show in general, I was disappointed that so many of the well known solar companies were not represented. I saw no booths for Outback, Morningstar, SMA, Enphase ?!?  Most of the major PV manufacturers were also missing.  Without these major players, how can InterSolar represent the latest and greatest in solar?
  • Dave AngeliniDave Angelini Solar Expert Posts: 3,304 ✭✭✭✭
    Go to the Vegas Show SPI, much bigger!  The Intersolar is for people in hot places and they get to cool down in San Francisco  ;)
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail offgridsolar@sti.net

  • SolraySolray Registered Users Posts: 246 ✭✭
    Mark Twain once said, the coldest winter he ever spent was a summer in San Francisco. Thanks, but no. :)
  • MarkCMarkC Solar Expert Posts: 155 ✭✭✭
    Outback also slipped the Skybox from about now to early 2018.
     Schneider is getting farther on the Bridge and some of the suppliers are training. I did training on the 400V LG RESU and I suppose if you have an electric car it might be nice but at 220 pounds I will not be anywhere near it. The 165 pound  Resu10 @ 48 is at my limit.


    Dave;
    Do you have a synopsis of the 400V LG training?  I'm most interested in any subjects related to 400 VDC bus protocols, including Power Line Communications, REBus (TM), Pika's "B-Link", anything "commercial" that support bi-directional energy flow to from grid/home support inverters and nominal 400 VDC battery systems.  This includes Pika and SolarEdge.  Do you know of other such inverters?  It appears that "Skybox" is more traditional 48 VDC battery bus?  I wonder if they will "boost" the charger/controller to handle the 400 VDC battery systems?

    Has anyone designed a 380 VDC system using the Pika B-Link?  This appears to require a somewhat modified system approach of +/- 190 VDC - seems unusual unless the Panasonics, LGs and Tesla are providing a center tap?  I know my Leaf has such a "tap" - the emergency disconnect at the 48th-49th cell of the 96 cell system but certainly not for any other function besides "fireman's disconnect".
    3850 watts - 14 - 275SW SolarWorld Panels, 4000 TL-US SMA Sunny Boy Grid tied inverter.  2760 Watts - 8 - 345XL Solar World Panels, 3000 TL-US SMA Sunny Boy GT inverter.   3000 watts SMA/SPS power.  PV "switchable" to MidNite Classic 250ks based charging of Golf cart + spare battery array of 8 - 155 AH 12V Trojans with an  APC SMT3000 - 48 volt DC=>120 Volt AC inverter for emergency off-grid.   Also, "PriUPS" backup generator with APC SURT6000/SURT003  => 192 volt DC/240 volt split phase AC inverter.  
  • Dave AngeliniDave Angelini Solar Expert Posts: 3,304 ✭✭✭✭
    The LG training  for the (10H 400vdc series only) is mainly common sense, following their directions, and the shipping safely and legally of the product to a home. It is not a hard course. The SMA is in beta testing for the 10H.

     As for Skybox, you are right. There was talk of higher voltage but I think most offgrid testers told them that the last thing we want is anything over 48VDC in our homes. We often can't get fire insurance as people in the big city can :)


    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail offgridsolar@sti.net

  • MarkCMarkC Solar Expert Posts: 155 ✭✭✭
    Got it Dave, thanks.  "Time will tell" about use of HV battery systems to help stabilize grid energy peak loadings and if such commercial designs and applications (with needed safety protocols) make it to the offgridders.  I'll not consider the HV systems until the energy contracts make it economical to do so - plus maybe help pay for my EV.   
    3850 watts - 14 - 275SW SolarWorld Panels, 4000 TL-US SMA Sunny Boy Grid tied inverter.  2760 Watts - 8 - 345XL Solar World Panels, 3000 TL-US SMA Sunny Boy GT inverter.   3000 watts SMA/SPS power.  PV "switchable" to MidNite Classic 250ks based charging of Golf cart + spare battery array of 8 - 155 AH 12V Trojans with an  APC SMT3000 - 48 volt DC=>120 Volt AC inverter for emergency off-grid.   Also, "PriUPS" backup generator with APC SURT6000/SURT003  => 192 volt DC/240 volt split phase AC inverter.  
  • bill von novakbill von novak Solar Expert Posts: 706 ✭✭✭✭
    MarkC said:
    Got it Dave, thanks.  "Time will tell" about use of HV battery systems to help stabilize grid energy peak loadings and if such commercial designs and applications (with needed safety protocols) make it to the offgridders.  I'll not consider the HV systems until the energy contracts make it economical to do so - plus maybe help pay for my EV.   
    The industry will eventually commonize on 400VDC, just from a cost and future-proofing perspective.  But it will be a long time before 48V goes away completely.
  • Dave AngeliniDave Angelini Solar Expert Posts: 3,304 ✭✭✭✭
    You might be right, you might be wrong also. A few good fires caused by batteries and who would want to be the deep pocket. Look at
    PG & E trying to dump their problems on the shareholders. Once the shareholders get burned it takes a long time to get investors back.


    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail offgridsolar@sti.net

  • jonrjonr Solar Expert Posts: 858 ✭✭✭✭
    I've seen no evidence that 48V is less of a fire hazard than 400V.  Shock hazard - clearly.
  • Dave AngeliniDave Angelini Solar Expert Posts: 3,304 ✭✭✭✭
    Just because you have not seen it does not mean it is not there. What is your background in these voltages? Do you live offgrid Jon?

    The path from a shock to an arc that starts a fire is not that hard to imagine. Defects in insulation, a bad arc fault detector, human error,
     and ? We are talking about  DIY systems and a pro systems also here? How good is the pro? Having a bad day?

    From what I have seen the two big players have stopped working on 400v equipment (for now) because they do not see the market and are reducing their risk to not making profit. An existing offgrid home can't add a 400v battery without replacing and rewiring equipment.  Adding the risk of 400v is not something most would do if they thought about it. 

    400V is great for the big city where insurance agents, fire hydrants, and fire houses are everywhere!

    The fact that 400vdc adds several additional failure modes to living offgrid was part of the feedback wrenches like me gave. I really was impressed with 400v at first. Then after some time, it sunk in how bad an idea it is. One of the testors lost the whole battery system.

    The problem was magnified for him as he could not just go to costco and buy 8 golf cart batteries. Think about that one when the lights go out ;)


    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail offgridsolar@sti.net

  • BB.BB. Super Moderators Posts: 26,837 admin
    More or less, safety regulation wise, 60 volts is the maximum voltage you can have before everything is behind locked doors and require trained service personal for installation/maintenance.

    Excluding the electronics issues (DC current is very difficult to prevent arc faults, once there has been a failure in insulation or electrical connection), is the battery bank itself.

    With 12 volts and 6x lead acid cells in series, you lose 1x cell (shorted/no longer holds a charge), and you drop your bus voltage by 2 volts--You now have 10-8 volt bus (0 volts across cell, or even -2 volts as it "reverse charges" and nothing works--Vary obvious when a cell has failed.

    With 48 volts and 24 cells in series, and a cell "goes bad", you now have a 46 working cells and 1 bad one with 0 to -2 volts across it--a 44-46 volt bus. Low bus voltage, but stuff still works sort of OK (42 volts is nominal "failed battery" bus voltage).

    400 volts or 200x cells in series, lose 1x cell, you are now looking at a 396-398 volt bus nominal voltage. Well within nominal operating voltage of bus--And beyond the accuracy of a typical volt meter (0.5% difference between 398 and 400 volts).

    Now you are needing per cell (or per small block of battery) monitoring. More wiring, more electronics, more things that can go wrong.

    Can it be done--Yes, electric car manufacture battery packs full of (upwards of 8,000?) ~18mm round x 65mm long batteries (about 2x the size of a AA battery). Not something I look forward too a typical off grid home battery bank.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • MarkCMarkC Solar Expert Posts: 155 ✭✭✭
    Waiting to see how the LG, Panasonic, Powerwall, etc. batteries work out in actual applications for grid stabilization.  My 2012 Nissan Leaf has proven (to me at least) several things about advanced lithium batteries in EV applications:
    - It can be used safely in a potentially dangerous application
    - It can be managed very effectively for high energy density and power rates
    - It can deteriorate more than expected in hot environments - even when "improved" technology is applied.  I.E., cooling/heating might be a requirement for certain environments (like South Texas).  
    - It results in one of the most fun cars to drive!
    3850 watts - 14 - 275SW SolarWorld Panels, 4000 TL-US SMA Sunny Boy Grid tied inverter.  2760 Watts - 8 - 345XL Solar World Panels, 3000 TL-US SMA Sunny Boy GT inverter.   3000 watts SMA/SPS power.  PV "switchable" to MidNite Classic 250ks based charging of Golf cart + spare battery array of 8 - 155 AH 12V Trojans with an  APC SMT3000 - 48 volt DC=>120 Volt AC inverter for emergency off-grid.   Also, "PriUPS" backup generator with APC SURT6000/SURT003  => 192 volt DC/240 volt split phase AC inverter.  
  • Dave AngeliniDave Angelini Solar Expert Posts: 3,304 ✭✭✭✭
    The Tesla and LG's I have direct experience with are mounted outdoors. They are degraded by temperature over 80F and log it. The Tesla actively cools the battery and the LG is passive with a heatsink. These are being mounted outdoors for safety but they are not required to be mounted there. It was the installers choice (mine too).  Basically on garage wall outside near the main and sub panels and used for grid back-up.

    Nice that the car could be pushed out of the garage  :) Just in case.

    Panasonic is making some Tesla batteries and I have not seen a prototype from them yet. The Sony version looks interesting to me with its pressure relief in the cell. The Tesla is ordered thru their network and the LG Resu 10H is out there for 4.5K$ wholesale. All need training to install and I like what wind and sun here is doing with the Simplyphi and battleborn. Nice entry level batteries but not really for a large home, yet!
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail offgridsolar@sti.net

  • cow_ranchercow_rancher Solar Expert Posts: 68 ✭✭✭
    BB. said:
    Can it be done--Yes, electric car manufacture battery packs full of (upwards of 8,000?) ~18mm round x 65mm long batteries (about 2x the size of a AA battery). Not something I look forward too a typical off grid home battery bank.

    Bill, what are they using for batteries, 18650's?

    Rancher
  • BB.BB. Super Moderators Posts: 26,837 admin
    Yes, and I guess, 20700 (20mm dia x 70.0mm long) is a new optimum design in new designs.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • bill von novakbill von novak Solar Expert Posts: 706 ✭✭✭✭
    Just because you have not seen it does not mean it is not there. What is your background in these voltages? Do you live offgrid Jon?

    The path from a shock to an arc that starts a fire is not that hard to imagine. Defects in insulation, a bad arc fault detector, human error,
     and ? We are talking about  DIY systems and a pro systems also here? How good is the pro? Having a bad day?

    From what I have seen the two big players have stopped working on 400v equipment (for now) because they do not see the market and are reducing their risk to not making profit. An existing offgrid home can't add a 400v battery without replacing and rewiring equipment.
    Agreed.  And that factor will keep 48V for a long time

    However, in the long term, it won't much matter what the battery voltage is, because people won't be dealing with it directly.  They will be buying systems from installers, and the installers will plug systems together using standard connectors from standards like REbus and gesis-NRG.  What buyers _will_ care about is price - and the higher voltages will allow smaller inverters, wiring, protection devices and conduit, which will lead to lower prices.

    Keep in mind that 48V came about partly because (now-ancient) telco systems used -48V as a standard for line voltages, line office power and battery backup.  And that led to the ready availability of 48V "rectifiers" (battery chargers) inverters, protection devices and switchgear.  That meant that when renewable energy needed more power than 12V could deliver, they turned to the existing 48V equipment at first, and later to the purpose-designed 48V equipment that companies like Iota and Trace started supplying.

    This pattern - where early availability leads to an implicit decision on a standard - is often called "path dependency."  The path (i.e. from telco to RE) determines the standards.  And that's happening now with 400 volt.  It's become the de facto standard for electric vehicles, mainly due to semiconductor availability.  It's becoming the de facto standard for building and data center power in Asia, due to how much money it saves on wiring and power conversion.  And the availability of equipment for those standards is now helping to drive the 400V standard.

    One of the testors lost the whole battery system.  The problem was magnified for him as he could not just go to costco and buy 8 golf cart batteries. Think about that one when the lights go out ;)

    Right.  But in Asia, he can get on Ebay (or their equivalent of Craigslist) and get a used 400V battery from a data center.  That will start to happen more and more in the US.


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