I'm trying to design a system to power my house during intermittent outages. It's quite severe in frequency but not super long in duration, we get recloser-related flickers (power drops out for a few seconds) once or twice a week, and longer outages around once a month (we are up to 9 long outages totaling 50 hours so far in 2024).
For longer outages I have a F150 Lightning which has an L14-30 plug, and can power the house using that. Ideally I wouldn't have to get out the big cable and hook it all up for <2 hour outages.
Currently I already have a main and sub breaker panel which should be perfect for this. The main panel has only the huge loads (AC, oven, and 2 EV chargers) and a 60A sub-feed to the sub panel. The sub panel has a generator interlock kit and the 30A generator inlet breaker as well.
The sub panel feeds everything else, plugs, lights, and the well pump. The panel is physically full, but the house was built with a 15A circuit for every single room plus a few more per floor for lights, so the load calculation is actually not that bad. I have an energy monitor on this panel as well, and daily average is around 40kWh/day (less than 2kW avg load) with peaks as high as 5kW, which is well within the capabilities of the Rosie inverter.
So, anyway, design questions:
- I could skip the E-panel entirely, feed the Rosie from the main panel with a 60A breaker, and feed in to the sub panel via the transfer switch breaker slot, which would give me a bypass and all of the required AC breakers. I would still need to add generator transfer somehow, probably another generator interlock breaker in the main panel.
- I could use the Rosie E-panel and repurpose the bypass breakers as a generator transfer on the inverter input, and again use the existing transfer breakers as an inverter bypass. This option has no path for power from the generator inlet to bypass the inverter, which is fine to me
- Server-rack lithium batteries, TBD brand. These are roughly 5.2kWh (52V / 100Ah), so a single battery will meet my 2 hour target. However, I'm slightly concerned that surges while grid-down may trip the battery overcurrent protection. If I'm careful with grid-down loads would it be a problem to install an undersized battery for the inverter?
- If I only use one battery, it already has a breaker included, so I could skip the E-panel entirely. This would make it much harder to upgrade the system in the future or add DC-coupled solar (I'd need a DC breaker panel). If I use >1 battery it would be easiest to use the E-panel for a DC breaker I think.
And finally, monitoring. I read the threads here about the Commbox and its death. Is there any code still floating around to do the communication bits? I already have a monitoring setup for everything else (Home Assistant for control + InfluxDB/Grafana for long term data), so I just need the raw data decoded from the bus and can take it from there. Ethernet would be ideal, but it doesn't look like the MNGP2 has Ethernet like the Classics, so CAN bus is the only option?
Any thoughts and opinions are welcome.
Do you already have a Rosie ?
I was just looking at the specs on the new midnite all in one and it has programmable inverter outputs for loads.
Larry
Usually the rack mount 5kWh batteries top out at around 100A of BMS output. So maybe 5000W or so of inverter output?
What you may want to consider given this is just a temp ride through situation is a golf cart type battery as they usually have a more robust 200A BMS to deal with motor load. This does have Bluetooth to monitor at cell level. With a 200A BMS you'll prob be fine for any normal Rosie load including surges to 10kW
https://www.ebay.com/itm/145965021334
I have seen the AIO inverter, but I think it's more power than I need. I'm also not setup well to shed loads, since I have so many small circuits, and energy monitoring shows it's not necessary to go bigger unless I want to talk about powering the AC or Oven. I could load-shed the oven I guess. The AC has a 130A LRA, so it's definitely not happening on any inverter.
Using golf cart batteries instead of sever rack batteries is a good idea. I didn't think of that. It'll probably be easier to mount on the wall too.
Here's the actual last 24 hours on the subpanel. Some days are worse of course, but the AIO would be massive overkill.
Quote from: Brucey on September 24, 2024, 07:49:57 AMUsually the rack mount 5kWh batteries top out at around 100A of BMS output. So maybe 5000W or so of inverter output?
What you may want to consider given this is just a temp ride through situation is a golf cart type battery as they usually have a more robust 200A BMS to deal with motor load. This does have Bluetooth to monitor at cell level. With a 200A BMS you'll prob be fine for any normal Rosie load including surges to 10kW
https://www.ebay.com/itm/145965021334
I don't agree with using that battery .It might cost more but a server rack battery or wall mount type from Orient Power will get you much better monitoring capabilities, better cells, and a metal case that you can open to service anything in the future. The new midnite server rack batteries coming on the market are also priced $1011 now from Current Connected
Larry
Quote from: ClassicCrazy on September 24, 2024, 01:53:20 PMQuote from: Brucey on September 24, 2024, 07:49:57 AMUsually the rack mount 5kWh batteries top out at around 100A of BMS output. So maybe 5000W or so of inverter output?
What you may want to consider given this is just a temp ride through situation is a golf cart type battery as they usually have a more robust 200A BMS to deal with motor load. This does have Bluetooth to monitor at cell level. With a 200A BMS you'll prob be fine for any normal Rosie load including surges to 10kW
https://www.ebay.com/itm/145965021334
I don't agree with using that battery .It might cost more but a server rack battery or wall mount type from Orient Power will get you much better monitoring capabilities, better cells, and a metal case that you can open to service anything in the future. The new midnite server rack batteries coming on the market are also priced $1011 now from Current Connected
Larry
Normally I would agree but the mnflow 5kWh is "only" good for 100A. In this specific case where he may need higher surge and low price I think the DC house golf cart 200A is a viable option. As background I have a bunch of non Bluetooth DC house/ecoworthy batteries and they all work fine as "black boxes".
Yes an ideal situation would be two mnflow 5kwh rack mounts but you'd be at $2k plus shipping, versus $700 or so. Grab two DC house and you have redundancy as well in case one has to be sent back for warrantee replacement?
Quote from: Brucey on September 24, 2024, 02:59:46 PMQuote from: ClassicCrazy on September 24, 2024, 01:53:20 PMQuote from: Brucey on September 24, 2024, 07:49:57 AMUsually the rack mount 5kWh batteries top out at around 100A of BMS output. So maybe 5000W or so of inverter output?
What you may want to consider given this is just a temp ride through situation is a golf cart type battery as they usually have a more robust 200A BMS to deal with motor load. This does have Bluetooth to monitor at cell level. With a 200A BMS you'll prob be fine for any normal Rosie load including surges to 10kW
https://www.ebay.com/itm/145965021334
I don't agree with using that battery .It might cost more but a server rack battery or wall mount type from Orient Power will get you much better monitoring capabilities, better cells, and a metal case that you can open to service anything in the future. The new midnite server rack batteries coming on the market are also priced $1011 now from Current Connected
Larry
Normally I would agree but the mnflow 5kWh is "only" good for 100A. In this specific case where he may need higher surge and low price I think the DC house golf cart 200A is a viable option. As background I have a bunch of non Bluetooth DC house/ecoworthy batteries and they all work fine as "black boxes".
Yes an ideal situation would be two mnflow 5kwh rack mounts but you'd be at $2k plus shipping, versus $700 or so. Grab two DC house and you have redundancy as well in case one has to be sent back for warrantee replacement?
okay on the 200a - have you or anyone ever tested that output from one battery ?
It would be interesting to know what kind of LiFePo4 cells can deliver 2C current .
Larry
Quote from: ClassicCrazy on September 24, 2024, 03:29:48 PMQuote from: Brucey on September 24, 2024, 02:59:46 PMQuote from: ClassicCrazy on September 24, 2024, 01:53:20 PMQuote from: Brucey on September 24, 2024, 07:49:57 AMUsually the rack mount 5kWh batteries top out at around 100A of BMS output. So maybe 5000W or so of inverter output?
What you may want to consider given this is just a temp ride through situation is a golf cart type battery as they usually have a more robust 200A BMS to deal with motor load. This does have Bluetooth to monitor at cell level. With a 200A BMS you'll prob be fine for any normal Rosie load including surges to 10kW
https://www.ebay.com/itm/145965021334
I don't agree with using that battery .It might cost more but a server rack battery or wall mount type from Orient Power will get you much better monitoring capabilities, better cells, and a metal case that you can open to service anything in the future. The new midnite server rack batteries coming on the market are also priced $1011 now from Current Connected
Larry
Normally I would agree but the mnflow 5kWh is "only" good for 100A. In this specific case where he may need higher surge and low price I think the DC house golf cart 200A is a viable option. As background I have a bunch of non Bluetooth DC house/ecoworthy batteries and they all work fine as "black boxes".
Yes an ideal situation would be two mnflow 5kwh rack mounts but you'd be at $2k plus shipping, versus $700 or so. Grab two DC house and you have redundancy as well in case one has to be sent back for warrantee replacement?
okay on the 200a - have you or anyone ever tested that output from one battery ?
It would be interesting to know what kind of LiFePo4 cells can deliver 2C current .
Larry
I believe there's a few batteries using 2C rated cells. Note this is just for discharge they all seem to have a 1C limit for charging.
Epoch golf cart rated battery has some more details here:
https://www.epochbatteries.com/products/48v-120ah-gc2-golf-cart-lifepo4-lithium-battery-complete-kit
On the cutting edge of LFP we have 4C rated charging from CATL:
https://chargedevs.com/newswire/catl-launches-fast-charging-lfp-battery-to-start-mass-production-this-year/
For a permanent install if the budget allows then certainly the mnflow 5 and 16kWh batteries would be far superior to the golf cart one from a cell, BMS, warranty, comms and overall system design perspective.