I am sharing a question on Enphase Community

 

https://community.enphase.com/s/question/0D53m00007P62ncCAB/grid-instability-issue-anyone-have-similar-issue-

 

It is a known issue, but, No one answer it. 

It is a FW of Inverter or Inverter's Problem, 

Due to this issue, can lost 2-4% Pure Production in System, 

Because eqch drop will affect 1.5% lost. 

 

// Contents //

 

I have bought Paid Manager service to check in detail, 

I just find any advice or idea who have experienced it before

 

temperature_spike_7dThis is 7d graph, you can see the green spike, that is the point of issue, 

I have checked in detail 

 

issue_beforeBefore the trouble, everything looks no issue, 

BUT, if check DC current, there is an different story

 

issue_right_before_recover 

DC current is not 0A, it is 0.59A with 40.34V DC voltage. 

micro inverter is not just shut-down, it is eating DC current, and temperature is going up

it is the temperature spike which has shown 7d graph. 

 

First issue has started on Aug 17, and it become more and frequently, 

Second issued inverter has started on Sep 2, and it become more and frequently. 

3 inverters are twice a day, and 2 inverters are once per 2-3 days. 

not sure, it will get worse or not. 

 

Any idea or advice about it ? 

 

ADD/EDIT: 

This issue has started on AUG/SEP 2021

and, getting worse - more frequently, 

Finally, it start to shutdown 3 times per inverter 

 

a 

ADD/EDIT : Bad news, It is affect on actual production

 

B84C6C6D-31D1-47C2-BA5B-86211EBCC0E8If see the green line, can see a power down at noon (it is average of 3 zone, 4-6 inverters are showing issue at only one zone even installed all at same time)

three inverters are showing error at similar time around noon. 

 

0E5DB1A8-59E5-4F04-959E-74212D589833it is power level using Production Meter Reading at Envoy every minute. 

yes, production rate is slowing down little bit at noon, 

It means, It is real Shut-down & No Production. 

 

ADD/EDIT : Is it really grid instability ? 

980E17FE-0D7D-43CC-AC97-339F2CE0EAF7I am running my system using AC Coupling Mode, GRID voltage is 237V (20V lower than actual 

grid voltage), and much stable. i have add RP230-30-10 filter, and 5 ferrite ring on L1/2 to filter 

noise. The issue has not been improved at all, not worst or better, same.

 

15161EED-9DE9-429A-8A41-C82E7AC8BF74 

i have 3 groups, the first string is, Group1-Group2-Junction-Envoy // 2nd string is Group3 - Junction - Envoy. No issue on 2nd string at all. Most of Group 1 show an issue, 1 out of 5 at group 2 shows an issue, 2-3 times per week.

 

Solar Report.png

 

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

as below

 

Picture1.png

 

 

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).

 

back_solar.png

 

 

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.

 

mppt.png

 

 

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).

 

whole system.png

 

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.

 

 

 

battery_dc_load.png

 

 

http://www.forby.com/solar/?detail=1&offset=0

 

 

Really, simple information but hard to find

 

passw.png

 

 

Recently, I have just updated little bit..

Add an accmulating graph, It can make me easy to read how much power has generated/used easily.

 

IMG_2088.jpeg

 

Around 50 yard in front of my house, there are some big trees.

I make some shadow on my house now.

 

IMG_2078.PNG

 

Power gain is not even, and, drop power at end of day ~

 

 

IMG_2079.jpeg

 

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.

 

IMG_2080.jpeg

 

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 = 3.3%

 

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.

 

* Good Article to Understand Shading Model

 

IMG_2076.jpeg

 

IMG_2077.PNG

 

First, I do not know, it has been caused by an Inverter or a Panel,

but, I am suspecting that the problem is happening by The Inverter.

 

Because I have verified with MPPT charger with same panel, and similar condition,

and, the power generating is +1/3 and shade two cells, and +2/3 when shade one cell.

 

Everybody know the shadow can reduce the power from Solar Panel,

there are 3~4 strings in a panel, if shading a string, the other strings can operated normally.

What will happen there is very small shadow 1-2 cells in a 60 cells panel ?

Yes, it can reduce the production to 30~60%,

 

Look at the detail production yield at my house,

Sunlight is coming from Right-Top side and, Dommer at Right Hand Side is making a shadow on Panel #6,

 

#1, at 09:19AM, half of two cells (right-top side, two cells in horisontal, not a panel) are shade, power production is just 10% via the other panel.

#2, at 10:23AM, very thin shade on a cell of panel (around 10~20% on right-top side of cell, not panel), production is 80% via the other panel.

#3, at 10:29AM, no shades, same power gain via the other panel.

 

In the solar panel test with MPPT charger,  the minimum power is aroudn 60% in #1, 90% in #2

It makes me suspect There is a critical problem in Enphase IQ inverter.

 

Note. Enphase IQ 7+, LG350N1C-V5

 

 

202007140920.png

 

202007141020.png

 

202007141030.png

 

봄이조아

Finally, I have got PTO, and my solar system start to work ~

 

http://www.forby.com/solar/?detail=1

 

IMG_1168.jpeg