What cable size for a 5kW solar system in Pakistan?

PILONE CABLES TECHNICAL TEAM

6 mm² on the DC strings, 6 mm² on the AC side to a 32 A MCB, 6 mm² for the earth.

A 5 kW inverter at full output draws 5000 ÷ 220 = 22.7 A on Pakistan's 220 V single-phase supply, which puts the AC run on a 32 A MCB with copper rated 46 A. On the roof, each string of five panels works at about 17.5 A of design current, and 6 mm² carries that out to a 43 m route inside a 3% voltage-drop budget. The catch is quantity, not size: two strings on two inverter inputs means four conductors down the same route.

A 5kW system needs three different cables

A rooftop system has three separate electrical jobs and each takes its own cable. The panels feed the inverter on direct current, outdoors, through single-core cable. The inverter feeds the house on 220 V alternating current through ordinary multi-core copper. And the aluminium frames the panels are bolted to have to be bonded back to earth.

A 5 kW rooftop solar system in Pakistan needs 6 mm² single-core DC cable for the panel strings and the runs down to the inverter, 6 mm² three-core copper from the inverter to the distribution board on a 32 A MCB, and 6 mm² for earthing the array frames and the inverter body. Those sizes hold for two strings of five panels feeding two MPPT inputs, 17.5 A of design current per string, routes of 43 m or less, and cable clipped direct at 30°C ambient. Parallel the two strings into a single home run and the current doubles to 35 A, which cuts the same 3% route limit to 21 m and pushes that run to 10 mm².

The three runs in a 5 kW rooftop system, two strings on two MPPT inputs. Current capacity per BS 7671, installation reference method C (clipped direct), 30°C ambient, two loaded conductors; conductor data per IEC 60228. Derate for conduit, bunching and roof heat. Verify sizing with a licensed electrician or your solar installer.
Run	Current	Cable	Capacity	Protection
Each panel string, DC	17.5 A design	6 mm² single core	46 A	DC isolator
Both strings paralleled, DC	35 A design	6 mm² to 21 m route, else 10 mm²	46 A / 63 A	DC isolator, string fuses
Inverter to AC board	22.7 A	6 mm² 3 core	46 A	32 A MCB
Array frames and inverter earth	—	6 mm²	—	—

Working the DC size out, step by step

Two numbers printed on the back of your own panels drive all of this: the short-circuit current, Isc, and the voltage at maximum power, Vmp. This worked example uses a plate reading Isc 14 A and Vmp 37 V, ten panels split into two series strings of five, and a 22 m route from the roof edge down to the inverter. Substitute your own figures in the same places.

String current. Panels in series all pass the same current, so each string carries one panel's Isc: 14 A.
Design current. Panels beat their plate figure on a bright, cold morning and hold it for hours. Size on 1.25 × Isc: 14 × 1.25 = 17.5 A per string.
String voltage. Five panels in series: 5 × 37 = 185 V at maximum power.
Voltage budget. Hold the DC side to 3%: 185 × 0.03 = 5.55 V.
The drop on 6 mm². 6 mm² drops 7.3 mV per amp per metre. Over the 22 m route: 7.3 × 17.5 × 22 ÷ 1000 = 2.81 V, or 1.5% — half the budget.
The same run on 4 mm². 11 × 17.5 × 22 ÷ 1000 = 4.24 V, or 2.3%. Inside 3%, but with only 6 m of route to spare before it is not.
Heat check. 6 mm² is rated 46 A clipped direct at 30°C against 17.5 A design current, so heat is never the limit here. Distance is.

That is why 6 mm² and not 4 mm². Both pass on paper at 22 m; only one still passes when the installer routes around a water tank and the run comes out at 30 m. The millivolt figure already covers the trip out and the trip back, so the 22 m in that sum is the route, measured one way — the cable you buy is twice it, per string.

How long a run each size covers

Heat is not what limits a 5 kW string; every size in this table carries the current with room to spare. Distance decides the size. The two columns are the two ways a 5 kW array gets wired, and they give very different answers.

Longest one-way route at 3% voltage drop on a 185 V string (5 × 37 V), at 17.5 A per string and 35 A with both strings paralleled. Buy twice these lengths per pair — the positive and the negative both travel the route. Voltage drop and current capacity per BS 7671, method C, 30°C, PVC; conductor data per IEC 60228. Recalculate for your own string current and voltage. Verify with a licensed electrician.
Size	Capacity	Voltage drop	Route, one string (17.5 A)	Route, strings paralleled (35 A)
2.5 mm²	27 A	18 mV/A/m	17 m	8 m
4 mm²	36 A	11 mV/A/m	28 m	14 m
6 mm²	46 A	7.3 mV/A/m	43 m	21 m
10 mm²	63 A	4.4 mV/A/m	72 m	36 m
16 mm²	85 A	2.8 mV/A/m	113 m	56 m

Read the right-hand column before anyone combines your strings on the roof to save cable. Paralleling halves the route you are allowed, and a 22 m route that was comfortable on 6 mm² becomes a 10 mm² job. Full spec and today's rate are on the 6mm solar cable and 10mm DC cable pages.

The AC side and the 32A breaker

Past the inverter it is an ordinary 220 V circuit and it is sized the ordinary way. A 5 kW inverter at full output draws 5000 ÷ 220 = 22.7 A. Apply the same 1.25 continuous-duty margin — 22.7 × 1.25 = 28.4 A — and the next standard breaker up is 32 A. Now the cable has to clear the breaker, not just the load. 4 mm² carries 36 A, only 4 A over a 32 A MCB, and that margin is gone the moment the cable enters conduit. 6 mm² at 46 A is the size to run.

Voltage drop on that run is small: over 10 m at 22.7 A on 6 mm², 7.3 × 22.7 × 10 ÷ 1000 = 1.66 V, or 0.75% of 220 V. The three cores are live, neutral and earth — 6mm three-core, off the standard cable range, is the usual pick. Bond the array frames and the inverter body back to the house earth with 6 mm²; the solar earthing cable guide covers the terminations. If the system is going on net metering, the run from that board on to the utility meter is a separate calculation — see the net metering cable size guide.

A panel string is live in daylight whether the inverter is switched on or off, and a DC arc does not self-extinguish the way an AC one does. Size the cable, the DC isolator and the string fusing together as one design.

How many metres of cable a 5kW roof takes

Sizes are easy to look up. Metres are what the quote is actually made of, and this is where a 5 kW job surprises people: two strings on two MPPT inputs send two pairs of conductors down the same route, so one 22 m route consumes 88 m of cable. Here is the count for one stated layout, to adjust against your own roof.

Cable count for one stated layout: ten panels in two rows of five on the roof slab, each row wired as one string, both strings brought to the roof edge and run down to an inverter on the ground floor, AC distribution board beside it. DC rows need twice the route length per pair because the positive and the negative each make the trip. Cable figures are the bare doubled route — add about 15% on top for slack, bends and re-terminations. Measure your own routes before ordering.
Run	Route	Cable to buy	Size
String 1 to roof edge, DC	6 m	12 m (6 red, 6 black)	6 mm²
String 2 to roof edge, DC	4 m	8 m (4 red, 4 black)	6 mm²
Roof edge to inverter, DC, both strings	22 m	88 m (2 pairs)	6 mm²
Inverter to AC board	10 m	10 m of 3 core	6 mm²
Frames, inverter, earth pit	24 m	24 m single core	6 mm²

Totals for that layout: 108 m of 6 mm² DC, evenly split red and black, plus 10 m of 6 mm² three-core and 24 m of 6 mm² earth. With 15% for slack, order 62 m of each colour. One warning before you compare quotes: coil lengths in this market are not standard, and price lists routinely print a coil price as though it were a per-metre price. Ask for the metres, ask which unit the number is in, and check both against the same run. Send us the route lengths on WhatsApp and we will quote the metres.

The cable for this system

Single-core solar DC cable in red and black jackets, cut back to show the stranded copper conductor, with a coil of red cable behind

6MM² · 1 CORE · DC SOLAR · 84/0.30 CLASS 5

6mm DC Solar Cable

Single-core stranded copper for the strings and the home run, drawn on the Pilone line in Lahore. Plain annealed class 5 copper, 84 strands of 0.30 mm — not tinned. A 100 m length holds about 5.33 kg of conductor at 53.3 kg/km, which is the fastest check on whether you were sold full copper: put the coil on a scale.

Factory-direct price

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Prices track the daily copper rate. Send the metres and your city on WhatsApp for the exact figure.

The AC side of the same system takes 6mm three-core, off the standard cable range, the earth takes 6mm earth cable, and a paralleled home run takes 10mm DC cable. All DC and solar cable sizes.

Current capacities on this page assume the cable is clipped direct in open air at 30°C. A run pulled through conduit, bunched with other circuits, on a roof slab in June carries less than the table says. Have a licensed electrician or your solar installer confirm the size for your layout — or start with the cable size calculator.

Frequently asked

5kW solar system ke liye kitna cable chahiye?

For the layout on this page it is 108 m of DC cable, 10 m of three-core AC and 24 m of earth. The DC figure surprises people: two strings on two MPPT inputs means two pairs of conductors down the same 22 m route, so that one route alone eats 88 m. Measure your routes, double them, then add about 15%.

Is 6mm enough for a 5kW solar system?

Yes, with each string on its own MPPT input: 17.5 A design current, and 6 mm² holds 3% drop out to a 43 m route on a 185 V string. Parallel the two strings into one home run and the current doubles to 35 A, the route limit falls to 21 m, and past that the home run wants 10 mm².

What MCB size for a 5kW inverter?

32 A. A 5 kW inverter at full output draws 5000 ÷ 220 = 22.7 A on single-phase supply. Add the 1.25 continuous-duty margin: 22.7 × 1.25 = 28.4 A, and the next standard breaker up is 32 A. The cable then has to clear 32 A, which is why the AC run is 6 mm² at 46 A rather than 4 mm² at 36 A.

4mm ya 6mm — which one should I use for my panels?

Route length decides it. At 17.5 A per string on a 185 V string, 4 mm² holds 3% drop to 28 m and 6 mm² to 43 m. A 5 kW inverter is usually a floor or two below the array, so most 5 kW roofs land between those two numbers and 6 mm² is the size with headroom left in it.

How do I check the cable is pure copper and not mixed?

Weigh it. Copper conductor runs 8.89 kg per km per mm², so 6 mm² is 53.3 kg/km — about 5.33 kg of conductor in 100 m, before the insulation. A coil that comes in well under that is either undersized or not full copper. Count the strands too: class 5 6 mm² is 84 strands of 0.30 mm.

Do I need 1500V rated cable, or is 1000V enough?

String voltage decides it, and a 5 kW roof is nowhere near either figure. Add up the Vmp of every panel in one series string: five panels at 37 V is 185 V, ten is 370 V. The 1000 V and 1500 V ratings matter on commercial strings of twenty-plus panels. Read the marking printed on the sheath of whatever you are sold, and check your inverter's maximum DC input voltage before lengthening a string.

Cable for the 5kW system, at the factory rate

We draw the copper in Lahore and sell it at the day's rate — no dealer margin. Send the route lengths and your city and we will price the metres: Punjab in 1–2 days, rest of Pakistan in 2–4.

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