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OffGridInTheCity Build

2nd AIMS, 5th Battery, 400a ABB shunt-trip, and Batrium tidy-up in place.  After 2 and 1/2 years its coming together!  This take the system up to
- 45 x 285w panes for a 12.8kw array.
- 5 x 260ah batteries (70 packs) for a 1300ah@48v Batrium monitored battery bank.
- 2 x AIMS 12K for a total of 24,000w (100a@240v) AC output. 

For orientation, here's a long view and a cross view of the solar control room...


The new heat pump is scheduled for next week.  Meanwhile, I just couldn't wait to try out the new AIMS.    Its just getting warm enough to run the 23yr old AC for a couple of hours in the afternoon - so I turned AIMS #2 on and wa-la, it seemed to work find for the last week until yesterday. 

Now remember, this 4 ton AC Compressor is 23yrs old and it blows motor capacitors every year - I learned how to replace them 7 yrs ago and have put in 5 new 'starter motor' capacitors in last 7 yrs.  So the AC Compressor is old / suspect!! - but I didn't expect this.

Today my new AIMS inverter powered-up and then WHAM, shut-off.   After much fear, I discovered that the 250a breaker between the battery bank and the inverter had tripped.   At 250a * 56v that means the Inverter was attempting more than 14,000watts!.   Look at what I found on my Omega power monitor log:

You can see the inverter turn on at 4:28:12 PM... and then 15sec later the automatic transfer switch changed over from grid to inverter power and WHAM -  95.4a @ 196.4v = 18,736 watts.     No wonder the 250a @ 48v circuit breaker tripped.    

Smile  Shows the value in having proper circuit breakers.

SO...  I'm going to leave it alone and wait for new Lennox XP24-048 heat pump install next week.   I was assured by the installer that this thing has variable speed 3-phase motor technology with has a couple of benefits.....   
- It is soft start.  So I shouldn't see anything like 100a @ 240v!!
- It takes in AC,  converts it to DC, then to 3-phase AC, which give the variable speed motor control.... which means the ATS (and the whole 60cycle syncing issue) will not cause any problems.

I'll report back next week with good news I hope Smile

P.S. GOVT OVERREACH: An intersting tid-bit on Lennox equipment according to the installer.  Lennox specifically made their modern heat-pumps to connect directly to solar panels...  BUT,  in Oregon USA,  they can't install the solar feature because Oregon requires a 'special'  solar certificate - which requires journeyman+test to get.  So Solar technician cannot do HVAC and HVAC cannot do solar - so the feature sits 'wasted' in Oregon.  Thank you government!!
cowpen and ajw22 like this post
Finally, after 1.5yrs of manual monitoring - the Batrium is actually hooked up thru 48v->24v step-down thru relay #1 to ABB 400a shunt-trip to disconnect the battery.    

Big shout-out to @LithiumSolar youtube:  "Connecting an ABB Shunt-Trip Breaker to the Batrium WatchMon 4 BMS" -
All I had to do was 'follow along'.    Thank you sir!
NEW HEAT PUMP: Brand new, whole house heat-pump install completed yesterday, first morning of heat, and look at this...

Only a 4,000watt draw heating a 2600 sq ft home up from night-time 19C/66F to day 23C/73F. This snapshot is mid-process (69F) at 5:30am, dark, and outdoor temp of 4C/39F.    Its an iComfort S30 'thermostat' using the 'IQ Schedule" to transition from night to day and the system is set for 100% heatpump when outdoor is >= -9C/15F - so heatpump may be limited due to outdoor temp and/or the "IQ Schedule" transition is programmed to raise the temp slowly over several hours - I don't know.

I live in "Zone 4 (moderate)" climate and the specific equipment is 
- Lennox "SLP98V" ...SLP98VUH090XV60C: 5 ton Furnace/Air-Handler dual fuel w/gas as 2nd fuel, indoor unit. -
- Lennox "XP25"  ... XP25-048:   4 ton HeatPump, outdoor unit -
- System is SEER 20, HSPF 9.5 according to the installer Smile

We'll see over time and of course AC is not yet in play..  but this very first 'solar powered',  'whole house heat' experience is *fantastic* (to me) and exceeds my expectations as I was estimating more like 6000watts from googling.    The heatpump 'soft start' is very nice -  you can see it ramp up slowly from 3amp @ 240v to 6a to 11a to 15a over a couple of minutes which is gentle on the inverter.
cowpen likes this post

The numbers show an average of 23kwh/day thru last 1/2 of March for a 2600sq ft home.  That's fantastic (to me) as my average solar production was 40kwh/day - which means there is enough power to heat my house.    Here's the National Weather info for March to help quantify what the 23kwh/day is doing - its a mild climate...    

More Detail:
We let it go down to 68F at night, so in the morning the system needs to raise the temp from 68F to 73F (5deg).    This takes about 1-3hrs depending on the outside temp.  At 30F the heat pump can barely raise the temp of the house (e.g. 3hrs).   At 35F or above, it's adequate (2hrs).   In the 40F(s) its much more responsive in raising the temp (<2hrs).  

One thing that jumps out at me - is that in a serious WTH...  it would be smarter to wait till late-morning for temps to raise before trying to warm the house.  Its only <30F during the day for 'a few days' a year on average here.  The rest of the time, its always >30F.
Thank you for the valuable information.iam very much impressed with this one.
Looking forward for the good posts.
APR 2020 Recap.   Remember this is 100% off-grid, cannot sell excess to power company. 

Generated 1862kwh per Midnite Classic and consumed 1475 kwh per meters on AIMs inverter output.   Averaged 79% efficiency.

Key Notes:
- Efficiency drop.   Since adding the 2nd AIMS,  average efficiency has dropped from 86% to 79% and I'm not sure why.
- Heat Pump.    The whole house heat pump used 389kwh for heat/cool.   Set for electric only (so not gas involved)    See weather info below.    
                      Note: HeatPump functions down to 30F outside temp - below that it struggles, cannot raise the house temp/minimal heat. 
- Generated more PV power than can be consumed...   
   * Midnite Classics are transitioning to float early afternoon most days...  leaving 15/day on the table leaving estimated (15kwh * 30days)= 450kwh lost.
   * Inverter was off 80hrs (out of 720 possible) for the month.  At 2300w/hour average consumption that's 80 * 2.3 = 184kwh lost due to lack of battery size.


Next Up:
- A new (6th) 260ah@48v battery is nearing completion to boost the battery bank to 1560ah@48v (e.g. 80kwh battery bank).   This should let me capture some of the lost PV power described above.

Observation so far... 
For 2020, I wanted enough PV array to heat/cool the house 9months out of 12.    So I nearly doubled the PV array and battery bank BUT the consumption of the heat pump is 'less than anticipated' so far - so I'm 'wasting' PV input power.    Maybe the hotter temps will cause Heat Pump to pick up the slack - not sure yet.
2 units have 2x the idle load than 1 have. So if 1 have 60w you now have 120w in losses. Thats why going with bigger or more units arent that efficient unless you really need it.

Get your self a Pool so you can waste the power into som nice warm baths Big Grin Im just about to start up my pool soon. Though i heat it mainly with firewood but the lazy days i dump excess into the pool
NOTE! My links supplied in this message may be affiliated with Ebay and by clicking on them you agree on the terms.
YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 100kWh LiFePo4 | 20kWh 14s 18650 |  66*260W Poly | ABB S3 and S5 Trip breakers
Upcoming: 14S 18650~30kWh
(05-01-2020, 05:26 PM)daromer Wrote: 2 units have 2x the idle load than 1 have. So if 1 have 60w you now have 120w in losses. Thats why going with bigger or more units arent that efficient unless you really need it.

Get your self a Pool so you can waste the power into som nice warm baths Big Grin Im just about to start up my pool soon. Though i heat it mainly with firewood but the lazy days i dump excess into the pool
The AIMS 12,000w have 200w/hour idle power consumption so I have the distribution panels wired so that they have load 24/7 have load all the time - e.g. they are never idle.  The single AIMS ran at 86% all last year.

Based on that I was expecting to get 86% efficiency from each inverter...   and 86% overall.   This logic....

[Battery] ----- (1000w) --> Inverter1 --> 850w       --> 1700w total out of 2000w input -->  1700/2000 = 85% overall effeciency.
              ----- (1000w) --> Inverter2 --> 850w  

But I'm wrong somewhere.  
Side Note:
 I can't use power saver mode because this 'probes for load' instead of affirmatively supplying load to the ATS to cause it to take power from the inverter instead of the grid.

>dump excess into the pool
Yea... I already have the Hybrid Hot Water Heater and the Heat Pump fully supplied. I'm literally powering the entire house except a few low-power odds and ends. The only things left are the Dryer & Oven and we use those once a week (not much)

I do have a spa but it looses its settings on ATS switchover if I hook 'the whole thing' to the system... so i need a way for it to keep it settings OR just ATS the heating coil alone - but its a bit of work. We'll see.
- Batteries 5 and 6 in place Smile  Brings the battery bank up to 80kwh (6 x 260ah@48v)

- Lennox whole house heat pump (2600 sq ft) in moderate climate,  May was 382 kwh,  Jun was 405kwh.  Continue to be fantastic numbers.     Here's the ATS powering the outside unit:

- The 12.8kw PV array is producing 80kwh/day.  Highest was 83.7kwh on Jun 25th.  70kwh/day'ish is powering the house 24/7!!    I'm running weeks at a time continuously on off-grid solar as long as the day is mostly clear - inverters never shut-off.   In fact, I'm loosing 5-10% of the available PV power because I can't consume it.    The efficiency of the whole house heat pump is so low compared to the previous AC that I overestimated the number of panels. 

Added the dryer into the off-grid wiring so that once or twice a week we use an extra 5% - considering adding the dishwasher as well - but I'm really down to low hanging fruit and don't want to 'jigger' the wiring into non-code hookup for just a bit of excess power.

Here's a typical day with full sun that the power company sees:

The 2 spikes are the spa on a 12hr cycle.  The rest is a background 200-300w/hour because I don't have *all* the circuits on off-grid.  The MTS only supports 10circuits - 2 are directed to dryer and the other 8 to higher usage circuits like the kitchen - but there are several others (spare bedroom, garage lights, ....) and its just not worth it to add a 2nd MTS.   In a real emergency I could double up circuits at the MTS - but that's not OK per code so not good for regular living. 

HAVE REACHED GOAL of 'powering the house comfortably' for 9 months of the year - so fantastically pleased to be able to do this.    

* Building battery #7 and #8 from RING packs...   Will try to fit into camper and/or hook to house system.

* Stockpile 30'ish panels for Nov, Dec, Jan (low power) months.  These could be propped up in the back yard and fed into the existing infrastructure if there ever were a Puerto Rico style emergency during winter.   This would bring the system up to 1000kwh/month - enough to heat/operate the house 20 of 30 days / month.  Not perfect but could work with that. Smile.

* 7 x 14 Cargo Trailer conversion to a camper.   Can stay warm in that thing for those 10 days/month with not enough power for heating house??   We'll see...   stay tuned. 

cowpen likes this post
Wow! Great work. Congrats!
Thanks for the project update. Very interesting.
Couple of questions:
What's a RING pack?
Do you have any issues with different charge / discharge characteristics of the 6 batteries you've built over time? Do they all pretty well stay in sync for SOC?

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