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Author Topic: Tesla Powerwall 2's + Solar iBoost = Problem?  (Read 3331 times)
Countrypaul
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« Reply #60 on: August 04, 2020, 10:20:55 AM »

As I said earlier, I'm not an electrician, my background is chemistry and IT for the Pharmaceutical and fine chemical industries.

I am not clear on the details of how your Powerwall works, but the fact it draws from all 3 batteries when there is a load on one phase (if I have understood correctly) suggests to me it could be interfering with what the iBoost expects. I don't know if you can turn the Powerwall off for a short period in order to test things, but if you can that might provide some clarity.

If the PV is generating say 10KW and the Powerwall is charging using all 10KW then the iBoost (P2) sees nothing.
If an oven 3KW (P3) is turned on, then that phase will not be able to charge at the same rate as other phases, so if the PW eases back its charging so all three phases are equal could that result in a 3KW export on phases 1 & 2?
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cg617
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« Reply #61 on: August 04, 2020, 03:55:57 PM »

Hi Aunat,

Again, the information you're providing is open to misunderstanding (I appreciate you don't have an electrical background), so a previous comment made about wiring diagrams or additional photos (diagrams preferred) would help although photo's might show the physical connectivity to be different to the diagram.  But it would baseline the starting point for investigation.

The Powerwalls are set to 5kW each (not 3.68kW as they are out of the box), which means I have 15kW of power (assuming it's dark, no solar).

Although 5kWh each does give 15kWh in total, you can't use power from one phase on another (phase shift).
So if all three powerwalls are on a single phase, then either your hot tub OR your immersion would benefit, not both (or neither if they are on the third phase).  If you have a powerwall on each phase (three powerwalls and three phases sounds much more sensible but 'design' might alter that connectivity), then all home devices can benefit, but the batteries won't be used evenly.  Unless the three powerwalls are sitting behind some monitoring control and can release energy to whichever phase needs it, not even sure that is an option.

As you can see, lots of questions, but until we understand the system, it's difficult to help.
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4kWp installation, installed in May 2013.
16 solar panels each with an Enphase edge invertor.
Averaging 4,450kWh / year.
Location South Essex
marcus
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« Reply #62 on: August 04, 2020, 04:23:30 PM »

I was thinking that Rogers advice had sorted the issue, and if what you say about the 3 powerwalls all charging/discharging as a balanced system is true, then that would certainly explain the iboost's behaviour, as it would see exports on ph2 overnight if the other two phases were seeing greater demand from the battery and divert those ph2 exports to the immersion.

If the 3 the powerwalls really are set up for balanced charge/discharge  wackoold (which might make sense if they were all on one phase, or in an industrial 3ph system where the bulk of the loads were balanced 3ph), then i'd look into getting them re-configured as 3 independent systems - If possible (ought to be - though you may need 3 gateways).
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cg617
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« Reply #63 on: August 04, 2020, 05:14:45 PM »

Just checked the spec of the powerwall 2 and noticed that the charge/discharge rate is 3.68kW charge and 5kW discharge.  I thought your figures were storage capacity. 
So basically you have 3x 'powerwall 2', total storage 39kWh.

The photo's you provided earlier show:-
Grid supply (bottom left)
going to (the grid meter), so far so good
then going to (a 3-phase breaker), still good
then going to (somewhere outside of the cabinet)  now we are into the realmes of vagueness and where we could use some clarity.

Tyhe three individual connectors at the top of the photo show connectivity from outside of the cabinet,
I'm guessing the leads coming in at the top are the solar generation (so from the 3-phase invertor and generation meter?)
and the 6 leads coming from the bottom are in vaguely the consumer cabinet and the power walls, but if anything else is going on, we don't see sight of it from the photos.

I seem to remember that the powerwall 2 is able to work in isolation of the grid and charge from the grid, so there may be some automatic isolators that cut the grid from everything else, that just makes it all the more 'interesting?'

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4kWp installation, installed in May 2013.
16 solar panels each with an Enphase edge invertor.
Averaging 4,450kWh / year.
Location South Essex
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