If say a result first, nothing improved yet.
More evidence(users) are complaining Ehphase IQ7+ Inverters are showing Random Produciton Drop with 'No Grid Profile' error with Firmware v4.27 or v4.28. I have thought firmware v4.28 can resolve the issue, but, not.
Now, I decide to change wiring for all inverters to check the difference.
This is the current layout, there is no issue at Rear Roof, Only issue at Front Side Upper/Lower Roof.
So, I just try to simplify the front root layout.
This is the current layout,
i have updated the layout as below
(1) rear roof - I have reduced the Q-cable length by 4'
(2) front roof - change the wiring, and reduce the power on the wire by half. the length has reduced by 4'. and, it is a new wire from roof to load-center usung 10 AWG THHN-2, have installed an independent breaker.
(3) porch - direct to JB, No more path thru on front roof panels, so, the power path have reduced by 12'
Base on my calculation, this change has lmproved for the voltage rising and interference of panels (inverters).
The first day of test, I cannot find any noticeable difference. actually, the inverters are showing error continously. (OTL), but, I wish to compare the difference before/after the layout changes (if there is any improvements)
At my location, the maximum possible production is around 6.711MWh with my system.
* 15 LG350N1C with IQ7+
But, Panels are installed on the three different location with various direction/tilt.
When consider the installation, Maximum value is 6.314MWh
But, I just get 6.166MWh due to the shading of dome/tree.
My estimated production is 6.129MWh (NREL Model 6.185MWh),
One of critical issue with an AC coupling system is happening when battery has fully discharged.
There is no way to recover back.
So, I decide to install an addtional DC coupling
Two panasonic HIT340 module on the shed at my back yard.
2 pannels are connected in series, it can generate 680W. (practically, it can generate 760~780W).
I have installed cheap MPPT charger,
Actually, this model can support 190V input, and working up to 160V.
When I make 2s 96cell module, Voc is around 130-140V. and Vmppt is around 120V.
It is too hard to use a generic 150V charger.
but, this MPPT controller is perfect in my case.
This is final connection,
I have installed 200W 48V to 12V DC2DC for Mini-computer (monitoring), NAS (Data storage & Web Server)
and Wireless Router (to keep on an in-house network).
I have installed 30kWh battery power
The useable capacity is around 24~25kWh. and, It is enough to supply 24 hours full power usage.
or 2-3 days limited power usage at my house.
Around 50 yard in front of my house, there are some big trees.
I make some shadow on my house now.
Power gain is not even, and, drop power at end of day ~
actually, the shadow is not much horrible to reduce the power to the diffusion power level.
but, It is a problem with solar power generation.
I hate the trees, but, I can do nothing ~ because it is not belong to me.
When install a solar system, need to consider more carefully,
The top-left panel are shaded, just little bit, What will happen ? just guess ?
Yea, lost 1/2 energy. Technically, solar panel is not working like that..
(1) 20 cells are in a string, and
(2) 3 strings in a panel (that is why there are three by-pass diode)
If half of one cell is shadowing, the cell will generate much lower current and/or voltage drop.
those string will makes much weak power such as 10-20% (power base on the diffusion light)
The other two strings will generate the power normally, so, it will generate 100%.
100% * 2 strings * 2/3 = 66.7%
10% * 1 strings * 1/3 = 33.3%
so, finally, the power generation should be around 70%, BUT, Enphase inverter has a problem in MPPT.
They track the lower peak instead higher peak in this situation. and generate 3.3% * 3 = 10% intead 70%.
by the result, just 50% of power can be havested in this situation.
This kind of problem is happening with a full sun-light condition also. when three string show full power,
but, there are some cell mis-matching. it will generate 2-3% flatten peak points near highest power point.
Enphase inverter is detecting the lowest peak one, instead highest one also. and, it can reduce the power by 2-3% also.
You can observe the discontinual highest power peak when shutting by cloude. because, when shuttering, this inver can find the highest point, but by time, keep going down, and stay at the lowest-peak power again.
Due to the tracking problem, Enphase Micro-inverter can not havest 100% enery, if they fix it.
The power yeild can be increased 1-2% for the good sun-light condition, and by 5-30% for the shading condition.
THIS IS FAKE !!!! DO NOT BE FOOLED, IT IS REVERSED !!!
If one cell has shaded completely, Panel voltage will drop 2/3 of normal voltage, will out-of-range of Enphase Inverter, and will not working. Even string/optimizer can handle it. BUT, Enphase MI can not handle it. Don't be fooled.
Top-right panel : 1/2 of one cell has shaded, that is why it can show 50%. if the cell has shaded completely, it will show 10%.