Hi

I am an old fart that has a double story roof, so when the panels were installed all I really got to see  of the connections were four cables coming down to my combiner box. How do I check if they were installed correctly ?

I have 10 x 455w panels. I did ask for and assume I got 2 strings of 5 panels.

The four wires go into the combiner box and two exit to the inverter.

I did a test when ac was off. My pool pump is running and the inverter (5kw) shows around 1.5kw being drawn. The input side shows also around 1.5kw from PV. As a small test I put the kettle on (2000w). Nothing more was being drawn from the panels so am assuming the balance was coming from the battery. Should my panels produce more under these circumstances ?

Thanks, any advice appreciated.

Bump

 

 In theory the panels should raise the output.

Need more info though to get an idea of what could be happening.

Which inverter have you got? Make & model? MPPT input specs and number of MPPTs? Does it blend power?

Was there enough sunlight at that time of day? Any clouds? Too early or too late in the day?

 

Combiner box, uses mc4 connectors

Can't see anything obviously wrong in the available information provided and the little bit I find on it online. That inverter looks like a Solarwise; speaking under correction, but seems like a form of Axpert derivative.

Most likely it's just a type that's not blending sources, and it's probably switching from solar to battery once the power demand exceeds the available solar resource in that moment, but that's a feature, not a fault.

Did you mean that once you turn the kettle on that the solar production drops away entirely? And that the entire load of around 3.5kW is being drawn from the battery?

 

 

Thanks

No, what I was looking at on the panel (yes the solarwise) was the PV input. At the time with the pool pump running and the normal household stuff, it showed 1.5kw with the output showing the same. When the kettle was switched on the output went up to 3.5kw but the PV input stayed the same. Sun was shinig and around 2pm. Load shedding was in effect.

1,5kW from ~4,5kW of panels seems rather low. But that would depend on the orientation of the panels and also the irradiation at the time.
The first thing I would check is the string voltages to see if they produce roughly the same voltage.
You would need to disconnect the solar from your inverter before testing each string, i.e. no load when you disconnect the MC-4s.
Disconnect the one string's MC-4 connectors and check the voltage and then check the other string.  From 5 of your Panels expect around 220-240V DC VOC in full sunlight. Losses may be a bit more; once again dependent on your panel orientation and also the length of the wires from the panels.
If the voltages are OK, then only connect one string back and do a load test.Then connect the other string and do the same load test and see if they give you the same max output wattage.
This you need to do under roughly the same solar conditions, ideally a bright sunny day and within a short time span to prevent changing environmental conditions influencing the tests.

Edited February 23, 20233 yr by zsde

Thanks I will give that a try. Is it possible that the installer could have mixed up the strings and how would this influence things

Hi zsde

I have just did as you said. Both strings are around 180V. They are not crossed and each string is producing independently. I cannot see or find a setting for max pv input.

One step further , I opened the combiner box and checked across the breaker, this V matches what is coming from the strings. Am I right in saying that the combiner box parallels the V when it sends it to the inverter.

Panels are North facing on a tile roof. Time is current, let's say 14:30

The two strings paralleled should give you the average of the voltages of the two strings.
Your Amps will be the sum of the two, i.e. about 20Amps. At 180V and 20 Amps. Whether your Inverter clips the Amps I wouldn't know, but a single MPPT would typically be around 18A max. There is normally no setting for max PV Input. The MPPT will clip at a max Ampage. Too high a voltage will burn out the MPPT. 
Lets assume 18A X 180V should give you a theoretical 3240W.
Just check in your Inverters specifications what the max Solar Input Amps are.
And check your string voltages again at around Midday (between 12 and 12:30), that would give you about the max Voltage you can typically expect.
 

Always surprised when we tend to think the highest voltage from the panels happen in peak time when production is the best.  In fact at maximum power point the voltage is lower. That is the function of the MPPT. 

The OP did not mention a time of the test so this is vital to know if the panels could be performing better. 

This picture shows voltage clearly. 

20 minutes ago, Scorp007 said:

maximum power point the voltage is lower.

True, the voltage drops quite a bit once load is applied. 
I was referring to testing the string voltage at midday. His string voltage yesterday was at around 14:30. 
After the string voltage check, he can then do the load test on each string individually.

22 hours ago, Stranger said:

 

17 hours ago, Stranger said:

Both strings are around 180V.

if that is without producing power, then the panel specs are probably bovine excreta... since your panels during the day, without producing power should provide a Voltage in excess of 5 x 41.25V = 205.25V at least and really 5 x 49.57V±3% so around 250V or thereabouts... I suspect these panels are actually really 300W each, or so, but I could be wrong, either way, based on the measurements given, this does not tally up with the sticker on the panel...

Hi, not sure what you mean by not producing power.

If for example I run my home office, which is around 400 W and then put on my 1.1Kw pool pump, I can see generation of around 1.5Kw coming from the panels. I can see this when load shedding is in effect. The inverter, if I am reading it right shows nothing being drawn from the battery.

The most V I have seen is around 220V, the most amps I have seen is around 12 A.

I have the system on solar priority, then utility, then battery. My battery is almost always full.

Thanks for all the replies, it goes a long way to understanding the system.

If we don't speak again today, have a great weekend.

PS: regardless of whether I have a perfect system or not. It beats the hell out of 8 hours or more a day load shedding.

2 hours ago, Stranger said:

Hi, not sure what you mean by not producing power.

when you measured the voltage of the panel strings was that disconnected from the inverter? if so,  they were not producing power, or at least the potential power was not being used/consumed and they should have been in Voc state, Voltage Open Circuit, if this was the case, you should have seen 49.57V x 5 panels being 250-odd Volt, but even under load/producing power their Voltage should be 41-odd Volt per panel and thus be sitting at more than 180V per string...

 

Just an update:

Well it appears that these panels like to be cold. Yesterday it was cooler and we had a lot of cloud cover. Now I see 220 V registering on the inverter.