Powerwall for Electrical Goodies

[higher_wire]

I'm designing a powerwall setup for the eventual move to off-grid solar. I'm collecting 18650s, and planning to connect them similar to HBPowerwall (14s80p, ~10kWh), and expand as I continue to collect cells.

• 48v system
  
• Charge controller: MPP PCM60x
  
• Inverter: TBD
  
• BMS: Leaning toward TinyBMS (awaiting a response to my questions)
  

I would also like to be able to charge a 48v electric bike and eventually an EV converted car, both of which will have 18650s in an 14sXXp configuration. That is, it would be nice to connect the bike's battery pack(s) to the powerwall or controller to charge, using connectors such as the APP PP75. As I understand, this will be doable in spite of differing capacities, as long as voltage capacity is the same.

I also plan to initially segregate the house so that all lights and small appliances running 110VAC will be able to run completely off-grid, with 220VAC (air conditioning, dryer, water heater, etc.) running on-grid in the short-term, due to a lack of cost-effective inverter options at the moment. My power company charges a monthly $50 "grid use" fee for on-grid solar, which is more than my average monthly bill (less taxes/fees), so I would like to keep it completely divorced to avoid this.

I'd appreciate any input on this proposed system.

[higher_wire]

So a full year later, and I actually have a working off-grid solar setup for most of my electrical needs (air conditioning, stove, and clothes dryer notwithstanding). My current specs and equipment are listed below. This post will act as a quick reference and table of contents as things change. Be on the lookout for a system schematic and more photos.

Note that I'm still cleaning up the wiring

• Powerwall Specs: 51.8v nominal, 166Ah capacity, 8.614 kWh
    
  
• Powerwall Configuration: 14s/80p (effectively 48v)
  -1120 cells @ 2078 mAh average/cell
  -Modular so cells can be added in 20p (40 Ah) blocks
  -I took inspiration from owitte's modular powerwall
  -Connections are 5/8" copper HVAC tubing with PEX wall holders
  -20p blocks use 2 strands of 12 AWG copper wire, with 28awg fuse wire on positive and 20awg negative
  -I'm using this battery disconnect on the battery negative
  
• Solar Panels: qty 40 165w Solar Frontier SF165S CIGS panels (datasheet)
  
• Charge Controller: qty 2 Sunnysky 60a MPPT
  -One controller for my rooftop array (24 panels)
  -One controller for my garagetop array (16 panels)
  -These allow you to set battery type, charge current, charge and voltage
  -It comes with two flimsy L brackets, and hangs awkwardly on my stucco wall. But I haven't had any issues otherwise.
  
  
  

• Inverter: Sigineer 6000w 48v, 240v split-phase (USA)
   
  
• BMS: Chargery BMS24T
  -The BMS controls charge and load via two Albright 200a SU-80 contactors, and claims a 1.2a balance function. It seems to be keeping the cells within ~50mA fairly well.
  -The BMS monitors SOC% using a 600a shunt on battery negative. I connected mine directly to the battery disconnect switch.
  
• Misc:
  -My panels came with a Hiasa enclosure. It included DIN rails, to which I was able to mount my breakers and ancillary equipment
  -My solar (2P) and charge (1P) breakers
  -My ANL battery fuse, connected to battery positive
  -Here's my ground junction
  -I used these DIN mounts for my contactors, fuse holder, ground junction, converter and fan control
  -Because Phoenix gets stupid hot in the summer, I wired a 12v buck converter and cooling fan control
  -The enclosure also came with an ABB INCA emergency stop button, which I wired to cutoff the contactors in case of emergency.
  -The inverter AC output is connected to the house via this Reliance 50a transfer switch
  

[Geek]

Excellent setup. Excellent write up. Thanks for sharing!

[higher_wire]

Thanks! I went back and forth between this and the HB style, but ultimately chose this for the ability to add capacity. I think I'll try the more compact shelf style like I've seen others use if/when I change things around (aka move to a bigger place).

Here are a few more shots. The BMS24 is up and running, and seems to be balancing things nicely. It unfortunately does not have a way to log information, nor do the charge controllers (they have RS485 ports, but the seller has said that they currently don't support logging). Being developed for electric transport rather than solar powerwall applications, functionality is limited compared to Batrium; but what can you expect at half the price.

The BMS has a warning LED and buzzer for if/when things go awry. I have the LED connected for quick reference, but not the buzzer. The BMS is designed to light the LED and cut load and/or charge whenever there's a fault.

[owitte]

So a full year later, and I actually have a working off-grid solar setup for most of my electrical needs (air conditioning, stove, and clothes dryer notwithstanding). My current specs and equipment are listed below. This post will act as a quick reference and table of contents as things change. Be on the lookout for a system schematic and more photos.

Note that I'm still cleaning up the wiring

• Powerwall Specs: 51.8v nominal, 166Ah capacity, 8.614 kWh
    
  
• Powerwall Configuration: 14s/80p (effectively 48v)
  -1120 cells @ 2078 mAh average/cell
  -Modular so cells can be added in 20p (40 Ah) blocks
  -I took inspiration from owitte's modular powerwall
  -Connections are 5/8" copper HVAC tubing with PEX wall holders
  -20p blocks use 2 strands of 12 AWG copper wire, with 28awg fuse wire on positive and 20awg negative
  -I'm using this battery disconnect on the battery negative
  
• Solar Panels: qty 40 165w Solar Frontier SF165S CIGS panels (datasheet)
  
• Charge Controller: qty 2 Sunnysky 60a MPPT
  -One controller for my rooftop array (24 panels)
  -One controller for my garagetop array (16 panels)
  -These allow you to set battery type, charge current, charge and voltage
  -It comes with two flimsy L brackets, and hangs awkwardly on my stucco wall. But I haven't had any issues otherwise.
  
  
  

• Inverter: Sigineer 6000w 48v, 240v split-phase (USA)
   
  
• BMS: Chargery BMS24T
  -The BMS controls charge and load via two Albright 200a SU-80 contactors, and claims a 1.2a balance function. It seems to be keeping the cells within ~50mA fairly well.
  -The BMS monitors SOC% using a 600a shunt on battery negative. I connected mine directly to the battery disconnect switch.
  
• Misc:
  -My panels came with a Hiasa enclosure. It included DIN rails, to which I was able to mount my breakers and ancillary equipment
  -My solar (2P) and charge (1P) breakers
  -My ANL battery fuse, connected to battery positive
  -Here's my ground junction
  -I used these DIN mounts for my contactors, fuse holder, ground junction, converter and fan control
  -Because Phoenix gets stupid hot in the summer, I wired a 12v buck converter and cooling fan control
  -The enclosure also came with an ABB INCA emergency stop button, which I wired to cutoff the contactors in case of emergency.
  -The inverter AC output is connected to the house via this Reliance 50a transfer switch
  

very nice setup, but your wall is way too small!

Have sun!
Oliver

[daromer]

Nice work!

[higher_wire]

very nice setup, but your wall is way too small!

Indeed it is! I have 7 more packs assembled, and picking up more cells soon. It gets me through the night as it is, but SOC hits about 5% at a voltage of ~48 by the time I check in the morning. I would have another full set of 14 packs, but I tried to run it with 14x1 packs without a proper BMS and ran a few flat.  

[higher_wire]

Update! I moved to a new house with a 200 sq.ft (18.5 sq.m) detached garage in the back yard. I've fitted 12 of my 165w panels to the flat roof and transferred all of my power conditioning equipment and batteries. I've dubbed this the scorpion shack because it was pretty derelict when I first moved in, and I've had a few run-ins. But I now have a nice little off-grid spot to build my batteries and take care of other projects. I am working to outfit my house with the rest of the panels.

I reconfigured my powerwall so it's now a powershelf. The plan is to stack packs vertically when I exceed the 6 pack depth limit.

[jdeadman]

Nice.

[OffGridInTheCity]

Very Cool! and I too have a working system that I hope to expand to power most of my house.  Its a lot of FUN!

I also made the decision to avoid power company requirements - so my system is also off-grid.  

I run the output of the Inverter into a sub-panel (seen in my profile picture) and then distribute power to various places.

1) Destination 1:  A 240v@50amp circuit is run from the main panel AND a 240v@50amp circuit is run from the inverter to the automatic transfer switch (box at bottom of picture).  The output of the automatic transfer switch feeds the Pro-Tran manual transfer switch - which is wired into main panel. 
 
The manual transfer switch gives individual circuit control because GEN position will get power from the automatic transfer switch and LINE position will get power from main panel as it originally did.

2) Destination 2:  A set of 30amp Go-Power automatic transfer switches power a set of 3000 watt APC UPSs.   I ran sockets to key computer/tv areas in house that are powered from the output of the APC UPS.   The 30amp Go-Powers get shore power from main panel and generator power from Inverter distribution box.  This takes care of sensitive equipment that can't take the automatic power switch that occurs twice a day.


All of this lets me
1) Shut the PV/off-grid system off to work on it without any disruption to the house power.
2) Consume all the PV/off-grid power...  and let grid take over automatically if the PV power is not enough for 24hrs for that day.   This let's me maximize my ROI and of course in an grid-down emergency I could use less power so it never shuts off.