Posted by: @tim441

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My system

Pitched roof solar panels. installed 2015. 45 deg pitch south facing. single storey.
7 x Sunmodule 285W Panels = 2kW nominal

Inverter
SolarEdge Model SE2200-ER-01-GBR

Flat roof solar panels installed 2021. 6 deg pitch east facing. single storey.
20 x Jinko 325W MC Modules = 6.5kW nominal

Inverter
Givenergy Model Giv-HY 5.0
Input Data (DC) Max DC Power 6500W
Output Data (AC) Nominal AC Output Power 5000W

Backup (EPS) Output
Max Power Output From Battery 2600W
Max Power Output (Battery + Solar) 5000W

Batteries
3 x Givenergy Model Giv-Bat 8.2
3 x 8.2kWh each = 24.6kWh max

2015 panels are on FIT but with new system no longer get deemed export (just actual production via FIT and actual export via Octopus export tariff)
As panels are accessible (single storey & from flat roof) I clean 3 monthly as pitch reduces self cleaning.

No major issues or changes with shading until mid afternoon (neighbour trees)

My problem

The larger system is monitored with Givenergy app and in 2022 produced acceptable 5100kw (taking into account low pitch & sub-optimal orientation)

The smaller system seems to have produced around 1450 - 1550kw/pa until last year when production was under 900kw

Original installer is no longer in business.

Inverter appears to be working - not sure if anything can be checked?

Any suggestions for checks I can make myself? 

checking individual panels?
Due to location I can safely access and remove individual panels.

Is it worth getting them checked by a "normal" electrician or needs someone with specific solar knowledge?

Are there any error messages being shown on the inverter?

Have cleared access to get to the inverter properly (it's in a loft! Loft is insulated so should not suffer from excess heat/cold/damp)

The inverter is showing a solid green light only - and appears to be working fine.

I can press the LCD light button which brings up various screens.

There is no wifi setup (presumably would need additional kit)

Also no LAN connection setup but I'm wondering if that is something I should do? I could get a long cable from inverter to my network I think. 

one thing that's interesting and may indicate a fault is the first status screen shows 
P_OK: 7/8
We actually have 7 panels on the main roof but have setup an 8th which is permanently 90% shaded (setup because supplier over ordered and we thought we might as well utilise & keep as spare). I believe they all have optimisers. so perhaps it is not showing as quite gloomy right now? I can check again on a sunny day.

I guess I should also check live production on a sunny day to see peak production?

any other suggestions? I can photo other inverter LCD screens if useful

Posted by: @tim441

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The smaller system seems to have produced around 1450 - 1550kw/pa until last year when production was under 900kw

Please clarify these stats for the (smaller) SolarEdge system.
You have stated the 'production' as kw/pa, so do we assume that all those output figures are the annual total?

The photo you've posted shows the SolarEdge inverter exporting 420w from a 7 panel array with max output of 2kW.
How typical is that?

What weather conditions were present at the time?

If the DC input is 371v, that suggests there's about 1.2A of current flowing from that array.
That can be checked with an AC/DC clamp-meter around either of the drop-wires entering the inverter.

AC/DC clamp meter, CPC/Farnell £25

@transparent thanks for that.

yes, I confirm output quoted was the totals per annum (i.e. previously circa 1500kw but last year under 900kw)

I have not previously been monitoring as I have no app or online info for this inverter (possibly something I should try to do if done easily - not sure how easy to setup). But now I have made access easier in the loft I will try and get a variety of readings at different times of day and conditions. So I don't know "typical" outputs.

Pic yesterday was generally cloudy conditions but did not check exactly. 

as a matter of interest current production in cloudy conditions:
2kw system: 190w (say 10% nominal)
6.5kw system: 1kw (say 15% nominal)

Perhaps that's the first thing I should monitor is comparable readings from the 2 systems to get %age vs nominal. I would like to think they should be similar - but lets see!

I will also get a clamp meter and see what readings I can take at same time

Those figures for a (light) cloudy day sound about right to me.
I generally assume that such conditions will decrease panel output to around one-seventh of that obtained under full sun.

Not having monitoring equipment is an issue which regularly crops up on this Forum.
It applies to almost every type of technology being installed by 'professionals'. 😒 

Not only does it make life difficult for those, like you, who are now trying to report whether you may (or may not) have a problem
... but it also reduces the knowledge-pool on energy matters within the wider population.

It seems odd to me that MCS fail to make adequate monitoring a mandatory part of installations by their accredited members.

@tim441

I think that you stated that you have 8 panels connected to the inverter, 7 in full sunlight and 1 shaded. Do you know if the panel are connected to the inverter as 1 string of 8 panels, or 2 strings of 4 panels?

How many optimizers are installed?

@derek-m I am pretty sure it is with optimisers on all panels. However its not entirely clear from paperwork. 

There is a small amount of early morning shade from a chimney to East and significant shade from (say) mid-afternoon from neighbour trees to west. So I'm pretty sure optimisers were required.

For the number of strings would we be able to tell from the number of DC cables entering inverter? There are 2.

I have a related question. I can see our 3kW array is producing energy, but we had a smart meter installed and it's reading is quite high given we've been optimising our daytime use of electricity according to how sunny it is.
First question: how can I be sure my solar electric is available for domestic use.
2nd question; the smart meter isn't -and won't work- as there is no mobile signal (it's a KAIFA MA 120)
Is there a smart meter that doesn't need a mobile signal?
The smart meter looks complicated but we weren't given any instructions. Is there anything useful I can get out of it?

@tim441 you must have Optimisers on all of those Sunmodule panels.
Their spec says the raw panels run at about 31v when MPPT is operating, and output just over 9A.

Your SolarEdge LCD shows 371v DC input, which is only achievable because the Optimisers are operating as DC-DC step-up Converters.
Without them present, all 8 panels in series could only generate about 250v.

@gutoffowc It should be recording both import & export even if not sending readings.

I assume its SMETS2? Which uses its own network - not standard mobile.

Your meter should have ‘Kaifa MA 120’ printed on it. It will automatically change between four different screens, so you don’t need to press anything.

This meter cycles through its four displays automatically. Your reading will be on the display with a number followed by kWh. 

@gutoffowc - great question...

... but it's difficult to answer immediately because it stretches across solar panels and smart meters, whilst skipping over the inverter and monitoring equipment in the middle.

Let's start by addressing the Smart Meter to understand what 'high' reading you are seeing there.
There's an existing topic on Smart Meter installation which would be an appropriate location to discuss those issues.

When you post there, please give us your rough geographical area and which network you use for your mobile phone.
Those details matter.

See you over there shortly 🙂