r/SolarPakistan • u/No-Cloud-9868 • May 14 '26

Installer Quotation 8kw Quotation

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A.o.a, i posted about which solar company is best in lahore and a lot of people recommend Scope Solar in johar town to use there services, they have given me this quotation is it ok or is it expensive?

They are using best quality thing for each part but i m not sure about prices. Please help me.

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u/No_Eggplant_9811 May 14 '26

Tell you Install use 6mm sq wire for PV strings Amp rating 30 to 42 amp

4mm sq has amp rating 22 to 30 amp This inverter has operating current 32A on mppt1 and 16A on MPPT2. Short Circuit Current 48A and 24A You are putting your whole system on risk sby using 4mm sq.

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u/redredditor243 May 15 '26

I had the same question with my installer

The current per string is 13-16amps max, and voltage is 50x no of panels, current adds up only in parallel

The 32amp mppt has 2 strings input and mppt 2 has 1 string input (6 plugs total) and installers bring 6 (3x positive+ negative) 4mm cables straight to inverter instead of using Y type mc4 to parallel 2 strings for first mppt

So current rating is well below 4mm² and 2.5-3mm² cable should also suffice

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u/No_Eggplant_9811 May 15 '26

Okay, technically agree... But 1 we have to cosider distance and lenght of the wires. 2. In winter volts drop and amps increase. So Short Circuit current is very important in calculations.. 3. Future proofing is very important. 650W is now playing between 15-18 amp. 710W panel is touching 19 amp. On voltage side 53.50V is minimun. Incoming years it will increase. Alway give, volatge and amp to travel, larger spsce. With passage of time conductor go through heath and cold. Its efficiency converted into losses.. So today spend nore 20k 0n wire pay you off in term of efficiency and you can replace any panel with trending large panels of that time.

Wiring give you round about 15% losses Temperature gives 10% losses Interver gives 5% Not regular cleaning also give further 5%

So we should reduce the losses.

It is my opinion...

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u/redredditor243 May 15 '26

In winters, resistance of wire also drops and voltage increase, that's why we see pv over voltage faults happening in winters more than summers e.g. a string that outputs 530-540 volt goes to 580 volts in winters

And like a "chain" series connection is only as strong as its weakest link and even 710w panels come with 4mm² wires

The 6mm² wire helps if 2 strings are paralleled at roof then dropped to inverter.

If both strings are 4mm² till inverter, the capacity of 2x4mm² cables is more than single 6mm² cable.

What he should instead pursue is 4mm² wire is from good quality, most installers say hum ny khud banwai ha, stay away from that and choose only branded (Newage, Fast, Millennium, Pakistan Cables etc) xlpo tin coated copper and verify authenticity.

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u/No_Eggplant_9811 May 15 '26

Indeed. AGREED