How Solar Panels Work — Step by Step
- Sunlight hits the panels: Solar panels absorb sunlight through photovoltaic (PV) cells made of silicon.
- DC electricity is generated: PV cells convert sunlight into direct current (DC) electricity.
- Inverter converts DC to AC: The inverter (Growatt or Fronus) converts DC into 220V AC electricity usable in your home.
- Powers your home: AC electricity flows to your home's distribution board and powers all your appliances.
- Excess sent to grid: Any surplus electricity is exported to the WAPDA grid via your net meter, earning you credits.
- Grid as backup: At night or on cloudy days, your home automatically draws from the grid as needed.
An on-grid (grid-tied) solar system is connected to the national electricity grid. It uses solar power during the day and draws from the grid at night. On-grid systems qualify for net metering but do not provide power during load-shedding unless paired with battery backup.
kWp (Kilowatt Peak) is the unit used to measure solar system size. It refers to the maximum power output under ideal sunlight conditions. A 10kWp system produces approximately 40–50 units (kWh) of electricity per day in Pakistan's climate.
How Panels Generate Electricity
A solar panel is made up of dozens of photovoltaic (PV) cells — thin silicon wafers sandwiched between glass. When sunlight (specifically, photons) strikes a silicon cell, it excites electrons and causes them to flow. That flow is direct current (DC) electricity.
On its own, DC electricity can't power a standard appliance — your ceiling fan, air conditioner, or refrigerator all run on alternating current (AC) at 220 V / 50 Hz (Pakistan grid standard). That's the inverter's job.
The amount of electricity a panel produces depends on:
- Panel wattage — higher-wattage panels produce more electricity per square foot of roof space.
- Peak sun hours — Lahore receives ~5.5 peak sun hours/day on average; Quetta ~6.5.
- Panel angle and shading — even partial shading on one cell reduces output for the whole string.
- Temperature — panels lose ~0.35–0.45% efficiency per degree Celsius above 25°C, so ventilation matters.
Key Components of a Solar System
1. Solar Panels (PV Modules)
The panels capture sunlight. Monocrystalline panels (single silicon crystal) are the industry standard for rooftop installations in Pakistan — they offer higher efficiency per square metre and better performance in partial shade than older polycrystalline models.
2. Inverter
The inverter converts DC from panels into AC for home use. It also monitors performance and, in on-grid systems, communicates with the utility grid. There are three main types:
- String inverter — most economical; all panels in a "string" are connected to one unit.
- Hybrid inverter — handles both solar input and battery storage; required for backup power.
- Microinverter — one small inverter per panel; best for shaded or complex roofs.
3. Mounting Structure
Panels are fixed to an aluminium racking system designed for your roof type (RCC slab, mild steel, or metal sheet). The angle is typically fixed at 25–30° in Pakistan to balance summer and winter performance.
4. Net Metering Meter (for on-grid systems)
A bi-directional smart meter measures both the electricity you draw from the grid and the surplus you export to it. Your DISCO (distribution company) installs this as part of the net-metering approval process.
5. Battery Bank (hybrid/off-grid only)
Lithium iron phosphate (LiFePO₄) batteries are now the preferred choice — they offer 4,000–6,000 charge cycles, safe chemistry, and faster charging than older lead-acid batteries. A 10 kWh battery bank typically provides 6–8 hours of basic household backup.
On-Grid vs Hybrid vs Off-Grid
In Pakistan in 2025, on-grid with net metering is the most popular choice for urban homes and businesses. Here's how the three types compare:
On-Grid vs Hybrid vs Off-Grid Solar — Which is Right for You?
| Feature | On-Grid | Hybrid | Off-Grid |
|---|---|---|---|
| Works during load-shedding | ❌ No | ✅ Yes (battery) | ✅ Yes |
| Net metering eligible | ✅ Yes | ✅ Yes | ❌ No |
| Battery required | ❌ No | ✅ Yes | ✅ Yes |
| Cost | Lowest | Medium | Highest |
| Best for | Low load-shedding areas | Most homes | Remote areas |
Most SolarLink residential customers choose hybrid systems — the battery provides peace of mind during load shedding while net metering keeps the payback period short.
What Affects System Size?
System size is measured in kilowatts (kW) — never in the number of panels. A single panel might be 580 W, so a 5 kW system contains roughly 8–9 panels.
The key metric is your monthly electricity consumption in kWh — this is printed on every WAPDA/LESCO bill. Don't size by rupee amount; tariffs change, but kWh consumption reflects your actual load.
- 300–500 kWh/month → 3–5 kW system
- 500–900 kWh/month → 5–8 kW system
- 900–1,500 kWh/month → 8–12 kW system
- Commercial / 1,500+ kWh/month → 12 kW and above; a detailed load study is required.
Other factors that influence final system design:
- Available roof area — a 10 kW system typically needs 50–65 m² of unshaded roof.
- Roof orientation — south-facing in Pakistan gets the most sun. East-west split arrays are possible.
- Future load growth — adding an EV charger or AC unit in 2 years? Size up now.
- Net-metering cap — your DISCO may limit export capacity; SolarLink knows each DISCO's current rules.
Maintenance & Lifespan
Solar systems have no moving parts, which makes them low-maintenance compared to diesel generators. That said, a few routine tasks keep output at peak:
- Panel cleaning — every 4–8 weeks in dusty areas (common across Punjab and Sindh). Dust and bird droppings can reduce output by 10–20% if left uncleaned.
- Visual inspection — monthly. Look for cracked glass, loose wiring, water pooling, or bird nesting under panels.
- Inverter check — monitor the inverter's app or display monthly; most modern inverters alert you to faults automatically.
- Annual service — SolarLink's maintenance plans include a full performance test, torque check on mounting bolts, and inverter firmware update.
Expected Lifespan
| Component | Warranty | Typical Lifespan |
|---|---|---|
| Monocrystalline panels | 25-yr performance | 30–35 years |
| String / hybrid inverter | 5–10 years | 10–15 years |
| LiFePO₄ batteries | 10 years / 4,000 cycles | 12–15 years |
| Mounting structure | 10 years | 25+ years |
5 Common Mistakes to Avoid
1. Sizing by bill amount instead of kWh consumption
Your electricity bill in PKR fluctuates with tariff hikes. Your actual load in kWh is the number that matters. Always ask for your last 12 months of kWh readings before sizing a system.
2. Ignoring future load growth
Adding an air conditioner, EV charger, or second residential unit two years after installation often means expensive system expansion. Design for your expected 5-year load.
3. Choosing the cheapest inverter
The inverter is the brain of your system and the component most likely to need replacement. No-brand or grey-market inverters may lack local warranty support, spare parts, or firmware updates. SolarLink only installs inverters from brands with a proper in-country service network.
4. Skipping the net-metering application
Without net metering, surplus electricity is wasted and you receive no bill credits. SolarLink handles the full application on your behalf — see our Net Metering Guide or the Net Metering Support service for details.
5. Delaying maintenance
A dirty or shaded panel doesn't fail visibly — it just reduces output silently. Set calendar reminders for cleaning and inspection, or enrol in an annual maintenance contract.