Off-Grid Solar System Design Pakistan 2026 — Complete Sizing & Protection Guide | CNC Electric
Off-grid solar in Pakistan is a different design problem from grid-tie or hybrid systems. There's no WAPDA to fall back on during cloudy weeks; no net-metering tariff to absorb daytime surplus; no AC reference for the inverter to synchronise against. The whole system must self-sustain — solar generation, battery storage, load delivery, and protection — using only the components on site. Get it wrong and the battery dies in 18 months from chronic undercharge, the inverter shuts down mid-evening from low DC voltage, or the system runs out of capacity during the first prolonged overcast spell. This guide walks through off-grid system design: load assessment, panel sizing, battery sizing for autonomy, charge-controller selection, and the full protection chain.
Who Should Build Off-Grid in Pakistan
| Use Case | Off-Grid Sense? | Alternative |
|---|---|---|
| Remote farmhouse without WAPDA | Yes — only option | — |
| Tube-well in agricultural land | Yes — common Pakistani off-grid use | — |
| Mountain area (Skardu, Hunza, Chitral) with intermittent WAPDA | Yes — hybrid risk is too high | — |
| Mobile / temporary installation | Yes | — |
| Urban home with frequent load-shedding | No — hybrid is much cheaper and net-metering eligible | Hybrid inverter |
| Commercial premises with reliable WAPDA | No — grid-tie or hybrid is more cost-effective | Grid-tie or hybrid |
| EV charging station / parking | Depends — typically grid-connected even at off-grid sites | Hybrid with EV charger |
Off-grid economics depend on the absence of grid alternative. If you can connect to WAPDA at any cost, hybrid wins on lifetime economics because net-metering monetises surplus daytime generation.
Step 1 — Load Assessment (The Critical Foundation)
Off-grid systems must size every component to actual loads, not nominal demand. Build the load schedule:
| Load | Power (W) | Daily Hours | Daily Energy (Wh) |
|---|---|---|---|
| LED lights (10 × 10 W) | 100 | 6 | 600 |
| Ceiling fans (3 × 75 W) | 225 | 10 | 2,250 |
| Refrigerator (200 W average) | 200 | 24 (with cycling) | 1,800-2,400 |
| 1.5-ton inverter AC | 1,200 W (running) | 6 (evening only) | 7,200 |
| TV + receiver | 120 | 5 | 600 |
| Water pump (0.5 HP) | 400 | 1 (filling tank) | 400 |
| Phone chargers, miscellaneous | 50 | variable | 200 |
| Daily total | 13,050-13,650 Wh |
Typical 3-BR Pakistani household: 12-15 kWh daily. Off-grid sizing must use the higher end of this range because there's no buffer. Add 20-30% safety margin: design target 16-20 kWh daily.
Step 2 — Panel Sizing
Panels must generate the daily load plus battery charging losses, accounting for Pakistani solar conditions:
- Average daily insolation: 5-5.5 peak sun hours (PSH) on Pakistani plains; 4.5-5 PSH on monsoon-affected areas; 6 PSH on northern dry areas
- System efficiency factor: 0.7-0.8 typical (accounts for soiling, temperature derating, cable losses, inverter conversion)
Required peak panel kW = (Daily energy in kWh) / (PSH × system efficiency)
For 18 kWh daily target on Pakistani plains (5 PSH × 0.75 efficiency):
kW peak = 18 / (5 × 0.75) = 4.8 kW. Round up to 5 kW panel array.
Panel count: 5,000 W / 420 W per panel = 12 panels.
For autonomy requirements (multi-day cloudy weather), increase the panel array by 20-30%: 6 kW (15 panels) gives 1.25-day excess generation buffer.
Step 3 — Battery Bank Sizing
Battery capacity covers evening loads + autonomy days:
- Daily evening / load-shedding energy: roughly 50-60% of daily total (ACs run mostly evening). For 18 kWh daily: ~10-11 kWh evening usage.
- Autonomy multiplier: Pakistani off-grid typically sizes 1-2 days of autonomy. Northern monsoon areas may need 3-4 days.
- Depth of discharge: 80-90% for LFP; 40-50% for lead-acid (long-life setting)
For a 2-day autonomy LFP system with 11 kWh evening usage:
Nameplate capacity = 11 × 2 / 0.85 = 26 kWh LFP
Equivalent lead-acid: 11 × 2 / 0.4 = 55 kWh nameplate (more than double the LFP requirement).
At 48 V system voltage: 26 kWh ÷ 48 V = 540 Ah lithium battery bank. Or 540 Ah of LFP packs in parallel (typically 4-6 × 100 Ah modules).
Step 4 — Inverter Sizing
Off-grid inverter handles the entire peak load simultaneously (no grid to share with):
- List instantaneous peak load: lights + fans + AC compressor + fridge + TV running at the same time
- Apply 1.5-2× margin for compressor inrush
For a household with 1.5-ton AC (peak 2 kW), fridge (200 W average, 600 W start), lights (100 W), fans (225 W), TV (120 W): total continuous peak around 2,750 W. Inverter sizing: 5 kW off-grid inverter handles this comfortably.
Step 5 — Charge Controller
The charge controller manages battery charging from solar panels. Two technologies:
- PWM (Pulse Width Modulation): Older, simpler, cheaper. Limits voltage to battery's terminal voltage; loses 15-25% of panel output. Acceptable for very small systems (under 500 W).
- MPPT (Maximum Power Point Tracking): Optimises panel voltage independently of battery voltage. 95-98% efficient. Required for any meaningful off-grid system.
Modern off-grid inverters usually have integrated MPPT charge controllers — Solis, Growatt, Sungrow, Studer all offer this. For larger off-grid systems (10 kW+ panel), external MPPT charge controllers (Victron, Studer) provide more flexibility.
Charge controller current rating: Panel current Isc × 1.25. For 5 kW @ 12 A Isc per string × 2 strings = 30 A combined. Need 40 A MPPT controller minimum.
Step 6 — The Protection Chain
Off-grid systems need every component of the standard solar protection chain:
- Panel string fuses (gPV class) — One per string, both legs
- DC combiner box breaker — Service disconnect for solar input
- Type 2 SPD on combiner — Lightning surge protection
- MPPT charge controller — Smart panel-to-battery management
- Battery-side fuse (class T) + DC breaker — Battery short-circuit protection + service disconnect
- Inverter input protection — Some integrated inside the inverter
- AC output MCB + RCBO + voltage protector — Standard home distribution protection on the inverter output
- SPD on AC output — Protects against surges entering through loads
Total protection cost for a 5-7 kW off-grid: Rs. 40,000-65,000. Significant but mandatory for system longevity.
Step 7 — Earthing & Lightning Protection
Off-grid systems often have inadequate earthing because the site lacks utility-grade infrastructure. Required:
- Dedicated earth rod — minimum 1.5 m copper-coated steel rod driven into ground. Resistance < 25 Ω.
- Equipotential bonding — all metal frames (panel rails, battery cabinet, inverter chassis) bonded together with 16-25 mm² copper.
- Lightning protection — for rooftop installations in lightning-prone areas (Northern Areas, monsoon zones), a Type 1+2 SPD plus separate lightning rod with dedicated earth path.
- Battery cabinet earth — battery enclosure bonded to system earth; each battery module's chassis bonded to cabinet.
Worked Example — 7 kW Off-Grid for Remote Farmhouse
- Load assessment: 14 kWh daily (lighter usage than urban average; no 1.5-ton AC)
- Autonomy target: 2 days (rural location, fewer cloudy days)
- Solar panels: 14 kWh / (5 PSH × 0.75) = 3.7 kW. Round up to 4 kW = 10 panels @ 400 W.
- Battery: 14 × 0.5 (evening usage) × 2 days / 0.85 (LFP DoD) = 16.5 kWh LFP. Round to 20 kWh.
- Battery voltage: 48 V → 416 Ah LFP bank (4 × 105 Ah packs in parallel)
- Inverter: 5 kW off-grid with integrated MPPT charge controller (Solis or Growatt)
- Charge controller current: 10 × 12 A Isc = 120 A peak input, derated to ~80 A operating. Inverter's integrated MPPT must handle this.
- Protection: 10 string fuses (5 strings × 2 legs), 1 combiner DC breaker, 1 Type 2 SPD, 1 class T battery fuse 200 A, 1 DC breaker 125 A, AC-side MCB + RCBO + VA protector + SPD
Estimated total cost: Panels Rs. 240,000; battery 20 kWh LFP Rs. 1,000,000; inverter 5 kW off-grid Rs. 380,000; protection package Rs. 55,000; cables and installation Rs. 120,000. Total ~Rs. 1,800,000.
Common Off-Grid Sizing Mistakes
- Under-sizing for cloudy weather. Pakistani monsoon (July-September in much of the country) can produce 30-50% less solar over a week. Off-grid systems need 1.5-2× the average-day capacity to handle these periods without battery depletion.
- Treating AC inrush as continuous load. A 1.5-ton AC's 20 A start current applied for hours = battery and inverter sized far too large. Use running current for energy calculation, start current only for inverter peak rating.
- Skipping the soiling derating. Dust on Pakistani panels (especially in arid plains) can reduce output by 10-25% if not cleaned. Apply soiling factor in efficiency calculation; plan regular cleaning.
- Wrong DOD on lead-acid. Discharging lead-acid below 50% to "stretch" the system cuts cycle life from 1,500 cycles to under 500. Always size lead-acid at 40-50% DoD for longevity.
- Single inverter without N+1 redundancy. Remote off-grid sites lose function entirely if the inverter fails. For mission-critical applications, consider parallel inverters or modular systems.
- Forgetting future load growth. Off-grid systems sized for current loads have no buffer for next year's EV charger or additional AC. Size 25-50% over current need; can add panels later but battery + inverter expansion is harder.
Frequently Asked Questions — Off-Grid Solar Pakistan
Should I build off-grid or hybrid solar in Pakistan?
Hybrid for 95% of Pakistani installations. Off-grid only when WAPDA connection is unavailable (remote farmhouse, tube-well, mountain area) or unreliable enough that grid-dependence is impractical. Hybrid is cheaper, supports net-metering tariffs, and provides backup during outages.
How much does a 5 kW off-grid system cost in Pakistan?
Approximate breakdown: panels Rs. 300,000-400,000; LFP battery 10-15 kWh Rs. 500,000-750,000; off-grid inverter 5 kW Rs. 280,000-380,000; protection Rs. 35,000-55,000; cables and installation Rs. 80,000-150,000. Total Rs. 1,200,000-1,750,000.
How big a battery do I need for off-grid?
Size for evening / overnight loads × autonomy days. Typical Pakistani 3-BR farmhouse with 14 kWh daily (~50% evening usage): 2-day autonomy requires 20-25 kWh LFP. Northern areas with extended cloudy periods: 30+ kWh.
Do I need a charge controller separate from the inverter?
Modern off-grid inverters have integrated MPPT charge controllers — no separate device needed for systems up to 10-15 kW panel array. For larger systems or specialised configurations, external MPPT (Victron, Studer) provides more flexibility but adds Rs. 50,000-150,000.
How many panels for a 14 kWh daily off-grid system?
14 kWh ÷ (5 PSH × 0.75 efficiency) = 3.7 kW peak. At 400 W per panel: 10 panels minimum. Add 20-30% margin for cloudy weather: 12-13 panels practical.
Can off-grid systems power air conditioners?
Yes with proper sizing. A 1.5-ton inverter AC running 6 evening hours uses ~7 kWh. For 18-20 kWh total daily off-grid system with appropriate battery and panel sizing, AC is feasible. Larger ACs or multiple ACs need proportionally larger systems.
What is the difference between PWM and MPPT charge controllers?
PWM is simpler and cheaper but wastes 15-25% of panel output by limiting panel voltage to battery voltage. MPPT optimises panel voltage independently of battery voltage; 95-98% efficient. MPPT is required for any practical off-grid system; PWM only acceptable for tiny installations under 500 W.
Do off-grid systems need NEPRA approval?
No — off-grid systems are not connected to WAPDA grid, so NEPRA net-metering rules don't apply. However, local building codes for safety (cable sizing, earthing, fire protection) still apply, and lightning protection is recommended for rooftop installations regardless of grid connection.
More CNC Electric Buyer's Guides
- Solar Inverter Selection Guide
- Battery Bank Pakistan — LFP vs Lead-Acid
- PV String Sizing — Voc & Temperature
- DC Fuse vs DC Breaker — Solar & Battery
- Solar Combiner Box Wiring
- DC Breaker Price in Pakistan 2026
- 1500V Industrial Solar
- MC4 Connectors Pakistan — Branded vs Generic, Crimping Guide