Dragan100

Me thinks you've had a bit of lightning about.

The problem will be figuring out the values for these.
The thing that looks like a diode is a thermal fuse. They operate at a particular temperature, as well as at a particular current. Hopefully there will be marks on there indicating the temperature and/or current. Typical ratings are 15 A or 20 A. This might carry the PV current, so if you can't find markings, size to that. If P7 is of of the PV inputs, and there is connectivity from P7 to one end of the fuse, then this seems likely. 
Movistors usually have a code on them; sometimes you can guess the ratings from that. They also have an energy (number of Joules) rating, but that's proportional to their diameter; if you replace with one of the same size (diameter and approximate thickness), this usually will have the correct rating. Its best not to have to guess the rating for movistors.
[ Edit: Example from above:

The "561" from the part number represents 560 V standoff voltage (like resistor code: 5, 6, and 1 zero). ]
The gas arrestor is obviously connecting to chassis/earth through the large via with the screw icon next to it. You likely can't get a rating off the blown one; if so, any of about the right size will provide some protection.

I found some micro cracks in the joints on PCB around the 230VAC OUT filter, on Lout and also on Cout (picture attached).
Then I re-soldered some larger joints on that section, reassembled everything back, connected LAB PSU 26VDC 10Amax (current limitation), No Grid, NO PV, for LOAD 100W Light bulb only.
Switching ON, everything OK! Firmware MCU display [U1 04.23] and for U2 no data on display?
Funs do a StartUP check up, then they are in standby.
Without load, the Inverter has its own consumption of around 28W (LAB PSU display). With OUT Load 100W light bulb => aprox. 125...130W is displayed on the LAB PSU display.
Output voltage 228VAC steady.
After about 20...30 minutes a fuzzy/sizzling noise starts to be heard, with the Inverter cassis open I try to locate the source of this fuzzy/sizzling noise!
230VAC OUT section,the output capacitor of the LC filtration OUT 230VAC starts "singing", a little later the output voltage starts to fluctuate/swinging from 180VAC... to 280VAC and back! Consumption during this swinging OUT voltage increased from the previous 130W to almost 200W.
I do not have an oscilloscope at this location, so I cannot provide some oscillograms at this time.
I have to unsolder OUT C 10uF/350V, measure it, looks good and see what quality it is!
I will try to find something suitable for replacement/test 5...12uF/400V (275VAC...440VAC), lead speacing /pitch 48mm or 33mm holes distance on PCB ,
what type of capacitor do you recommend I mount for this 230VAC LC filtering Cout?
 
Cout for AC filtering, Grid interface, High current peak capabilities, UPS, ...
WIMA MKP 4F series
EPCOS-TDK B3235 series , B3275 series
Panasonic EZPQ series
KEMET C4AF series
Vishay MKP1847C series
 

Almost good enough cup grounding more efficient answer for your friend.

is this good enough for grounding ? Asking for a friend.
 

Well done.
You won't see the U2 firmware version unless there is at least about 5 volts more than battery voltage at the PV input. You could probably force the solar charger to "detect" PV and switch itself on; see the left side of SCC3.PNG here.
I don't have any 04.xx main firmwares in my collection, sorry.
That sounds normal.
Could it be that the leads have tarnished, and you just need to clean the leads and resolder?
I've had it happen that capacitors "sing", yet appear to be working normally. I don't like that, so I replace them. These would be film capacitors. I would only replace it with one of the exact same capacitance, i.e. 10μF.
I clicked on the EPCOT link and it didn't respond in reasonable time; EPCOT, Panasonic, and Kemet brands should be fine, as long as they are film capacitors with appropriate AC voltage ratings. All capacitors of that size are likely to be film types. I don't expect the type of file (polystyrene, polypropylene etc) to be critical.

I notice the processor (first photo, bottom right) is an MC9S08, which is an 8 bit processor, only used in the smallest models. If you tell me the main firmware version, there is a chance that I can identify the model from that.

As basic as it sounds, I've had a lot of random errors caused by dry/aged capacitors on the battery SPS circuits. If the inverter in question is more than 3 years old the capacitors will likely need checking and replacing.
 
The manual looks like the unit is a VMII design. For the VM models the bus soft start circuits are on the solar controller board so when testing startup/inverting this has to be plugged in...when I first worked on one I spent 2 days looking for non-existent faults because I didn't have the board connected.

Thanks for the quick reply @Shadders,
the inverter is 1 year old, it has about 500 hours of Inverter work so far, mostly the complete system is switched OFF, the batteries are charged via PV as needed when/and only when arriving at the location. Only then do switch the system to All-ON. The cottage is located at the edge of the forest, a rather remote location, the cottage is used approximately once a week.
So I doubt that the electrolytes are already dried out, but I will still visually inspect/Checking/measure them on the PCB.
A friend (the owner of the cottage) checked the inverter's error history yesterday, the Error code 05 ([05 ]Output short circuited or over temperature is detected by internal converter components) also appeared (only once), and that was when the system was connected to the generator set, there was not much PV energy due to bad weather, but used a generator to supplement the batteries and enable the operation of the refrigerator and lights (tot 500Wmax, so it was not Output short circuited , so more likely an Overtemperature fault. As Input Utility, the generator enabled Inverter Bypass mode and additionally charged batteries, solar energy was not available => Program 01 SOL!
So here I see a similar problem around DC<->AC , Utility provides Bypass to OUT 230VAC, and we have energy transfer AC<->DC=>DC<->DC=>Charge batteries, so again I suspect AC<->DC IGBT Gate drive problem like @BritishRacingGreen mentioned, not correct/insufficient Gate drive/Gate ON/OFF times, Overlapping ON/OFF Gate times/too short DeadTime due to bad Gate drive/IGBT Id current in FullBridge on one or both half bridges partial current pass through , so I suspect a problem here as well around this Error code 05 like IGBT Overtemperature.
Utility charging was set in Program 11 to 15A (insted 25A default), and in Program 02 Maximum charging current: To configure the total charging current for solar and utility chargers, was set to 50A(default for PWM)
LP
Dragan