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Powerwall Build
#1
Hi,

I finally got my build started and decided to either go big or go homeThis is after I installed a 2.4kW Pylontech battery and Goodwe inverter for the prettiest penny in my pocket! having "supervised" the installation of the solar system I told my inner self "that isn't too hard..." So I started off with a  24V system with 1120 cells on a 7S 160 configuration which I kept running for a few months before I found a secondhand Goodwe inverter. 



with another 14S 80P pack ready i scaled up to a 48V  system and currently have 2240 cells in service in a 14S 160P setup. 


This system has been primarily servicing light loads (lights only) as I monitored temperature, balancing of the packs as well as the voltage sag. It has gone pretty well so far...no explosions, no fires so a few more critical loads have been added on to the DB and so far life is good.

The initial setup wasn't the tidiest (and it hasn't improved much) but the plan to improve it is slowly coming together. So I currently have a Chinese 14S BMS running with this pack and it seems for now to be up to the job. I have my eye on a batrium system but the cost is a bit of a hurdle so it will wait a while longer.


My goal is a 50kWh power wall and hopefully to learn faster than I am building at the moment! I am using an old sever cabinet as my box and haven't  used the space efficiently in it but now hope to slowly fix that by building my new 14S 80P packs so that they can snugly fit into the cabinet. I am considering building sliding shelving so as to make maintenance and upgrading/adding to the powerwall easier, but time will tell whether my welding skills are up to the job.
ajw22, OffGridInTheCity, Korishan And 1 others like this post
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#2
Hahaha Love the battery pack holders! Big Grin True DIY right there

nice layout, too. Nice idea for storing the packs outside, but out of weather. Is the door metal?
chuckp and madmike like this post
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#3
I really like that battery box. Have been looking for something similar. What is it from?
Stingy49 likes this post
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#4
(12-03-2019, 02:50 PM)cowpen Wrote: I really like that battery box. Have been looking for something similar. What is it from?

Electrical enclosures like those are expensive new! Got to find them in scrap yards when they discard old equipment. We have a few from old machinery at work that I have to remember to cannibalize before they go to the scrap yard.

https://www.automationdirect.com/adc/sho...enclosures
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#5
(12-03-2019, 01:47 PM)Korishan Wrote: Hahaha  Love the battery pack holders!  Big Grin  True DIY right there

nice layout, too. Nice idea for storing the packs outside, but out of weather. Is the door metal?
The cabinet is an old server cabinet that I was able to get my hands on. I water proofed the top that had the cable opening with some fibreglass and Sika 560 (roofing material) i had left over after doing some roof work on the house.

(12-03-2019, 01:47 PM)Korishan Wrote: Hahaha  Love the battery pack holders!  Big Grin  True DIY right there

nice layout, too. Nice idea for storing the packs outside, but out of weather. Is the door metal?
 
the Cabinet is all sheet metal. Being on the narrow side I bolted it to the wall just to make sure it didn't tip over being top heavy with the batteries all at middle level (just like me and my gut!).

(12-05-2019, 04:08 PM)not2bme Wrote:
(12-03-2019, 02:50 PM)cowpen Wrote: I really like that battery box. Have been looking for something similar. What is it from?

Electrical enclosures like those are expensive new! Got to find them in scrap yards when they discard old equipment. We have a few from old machinery at work that I have to remember to cannibalize before they go to the scrap yard.

https://www.automationdirect.com/adc/sho...enclosures
mine is a decommissioned server rack unit. These can be got for a song and if lucky, free if you can haul it away!
Korishan likes this post
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#6
Very cool and looks like its turning into a serious effort! I'm about 2 1/2 in now and nearing 8500 cells... and my focus has come around to "Ongoing Power Production" - in other words I need to use the system long term and try to get some $ back that I promised my wife Smile.

I don't see your PV array size but if it helps you - I've (accidentally/haphazardly) come to understand some over-arching design goals and now have actual power production experience. For example, you said 'go big' and went to 48v - great move! 48v is a great practical decision for whole house power production and there are lots of products.

If it helps you, I've found that a 40kwh battery bank paired with a 7kw PV array produced 9,000kwh and resulted in a 32% DOD. This 32% DOD was more accidental that planned but I'm happy with this as it gives me a chance for a long battery life. As I go to a 13kw PV array I plan to expand the battery bank to 66kwh (8500 cells) to maintain < 40% DOD.

You said you are shooting for a 50kwh battery bank - if you are OK sharing, I'd be interesting to hear more about your PV arrays size and design goals.
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#7
(12-09-2019, 06:04 PM)OffGridInTheCity Wrote: Very cool and looks like its turning into a serious effort!    I'm about 2 1/2 in now and nearing 8500 cells... and my focus has come around to "Ongoing Power Production" - in other words  I need to use the system long term and try to get some $ back that I promised my wife Smile.

I don't see your PV array size but if it helps you - I've (accidentally/haphazardly) come to understand some over-arching design goals and now have actual power production experience.    For example, you said 'go big' and went to 48v - great move!    48v is a great practical decision for whole house power production and there are lots of products. 

If it helps you, I've found that a 40kwh battery bank paired with a 7kw PV array produced 9,000kwh and resulted in a 32% DOD.  This 32% DOD was more accidental that planned but I'm happy with this as it gives me a chance for a long battery life.    As I go to a 13kw PV array I plan to expand the battery bank to 66kwh (8500 cells) to maintain < 40% DOD.

You said you are shooting for a 50kwh battery bank - if you are OK sharing, I'd be interesting to hear more about your PV arrays size and design goals.
I currently have 2 goodwe inverters 3kW and 5kW installed and running. So I am looking to end up with two powerwalls either in one large server rack is possible, my wish list includes a batrium BMS (funds allowing).

At the moment I have a 3.3kW array and this will take just under 2 days to fully charge my batteries. It is a work in progress to get the solar array right sized. roof space is also at a premium as I have limited north facing roof (if i could I would have rotated the house... just a little bit... but alas!). 

Hopefully 2020 will be the year i cover the rest of the north facing roof and use the east and west facing roof space. I may just be able to get the batteries fulling charged in a day.
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#8
madmike Wrote:
OffGridInTheCity Wrote:Very cool and looks like its turning into a serious effort!    I'm about 2 1/2 in now and nearing 8500 cells... and my focus has come around to "Ongoing Power Production" - in other words  I need to use the system long term and try to get some $ back that I promised my wife Smile.

I don't see your PV array size but if it helps you - I've (accidentally/haphazardly) come to understand some over-arching design goals and now have actual power production experience.    For example, you said 'go big' and went to 48v - great move!    48v is a great practical decision for whole house power production and there are lots of products. 

If it helps you, I've found that a 40kwh battery bank paired with a 7kw PV array produced 9,000kwh and resulted in a 32% DOD.  This 32% DOD was more accidental that planned but I'm happy with this as it gives me a chance for a long battery life.    As I go to a 13kw PV array I plan to expand the battery bank to 66kwh (8500 cells) to maintain < 40% DOD.

You said you are shooting for a 50kwh battery bank - if you are OK sharing, I'd be interesting to hear more about your PV arrays size and design goals.
I currently have 2 goodwe inverters 3kW and 5kW installed and running. So I am looking to end up with two powerwalls either in one large server rack is possible, my wish list includes a batrium BMS (funds allowing).

At the moment I have a 3.3kW array and this will take just under 2 days to fully charge my batteries. It is a work in progress to get the solar array right sized. roof space is also at a premium as I have limited north facing roof (if i could I would have rotated the house... just a little bit... but alas!). 

Hopefully 2020 will be the year i cover the rest of the north facing roof and use the east and west facing roof space. I may just be able to get the batteries fulling charged in a day.

How does the Goodwe inverters work with custom battery solutions? I did find another thread about this and plenty of problems with firmwares and communication with the goodwe unit. I myself have a 10kW Goodwe hybrid unit and 60pcs solar arrays (neither installed yet). I am worried I will have to get an expensive low capacity battery solution like pylontech. That would suck and I would need to reconsider the goodwe inverter.
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#9
>I may just be able to get the batteries fulling charged in a day.
My goal is to consume all the PV array power produced.  IF I could do it with 1% battery charge (batteries just stayed at 3.7v all day) then that would be ideal as the battery would last forever.   The purpose of the battery is to buffer the variability between PV array power input and consumption.

I cringe at the idea of fully charging my batteries as this reduces their life span Smile

For the year 2019 I averaged 31.4% DOD but this included lows of 14% and highs of 45%  (in range between 4.0v/cell and 3.5v/cell) because of all the variables in PV power production.   Some days - e.g. the 45% DOD the sun is strong and consumption was week.   In some days e.g. 14% the sun was weak and consumption was high.    The 14% is sort of the minimum as I don't want the inverter to cycle on/off several times a day - the system is tuned to on / off once per day.  
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