How to Size a Solar System for Load Shedding in 2026: A Room-by-Room Method
Learning how to size a solar system for load shedding is the single skill that separates a smooth off-grid evening from a dead battery at 9 PM. In 2026, most Pakistani households no longer ask if they should go solar, but exactly how many panels, how big a battery, and how large an inverter they truly need. This guide skips the sales talk and walks you through a practical, room-by-room method you can do with a pen and your last electricity bill.
The goal is simple: cover your essential loads during outages without overpaying for capacity you will never use. Get the sizing right and your system pays for itself faster while keeping fans, lights, and the fridge running through every scheduled cut.
Step 1: Build a Load List Before You Size a Solar System
Everything starts with a load list. Walk through your home and write down every appliance you want running during load shedding, along with its wattage. Wattage is printed on the appliance label or in its manual.
Do not guess. A ceiling fan pulls very different power from an inverter AC, and mixing them up wrecks your battery math.
A sample household load list
| Appliance | Watts each | Qty | Hours/day on backup | Wh/day |
|---|---|---|---|---|
| LED lights | 12 | 8 | 5 | 480 |
| Ceiling fans | 75 | 4 | 8 | 2,400 |
| Refrigerator (avg) | 150 | 1 | 10 | 1,500 |
| TV + router | 110 | 1 | 5 | 550 |
| Water pump (0.5 HP) | 400 | 1 | 1 | 400 |
| Phone / laptop charging | 90 | 1 | 3 | 270 |
| Total | 5,600 Wh |
This example home needs roughly 5.6 kWh per day of backed-up energy. Your number will differ, but the method is identical.
Step 2: Size the Inverter for Peak Load
Your inverter must handle the highest number of watts running at the same moment, not the daily total. Add up everything that could switch on together, then add a 20 to 30 percent buffer for surge from motors like pumps and compressors.
- Sum of simultaneous loads in the example: about 1,600 W.
- Add 25 percent surge headroom: roughly 2,000 W.
- Choose a 3 kW hybrid inverter so you have room to grow.
A hybrid inverter is worth the extra cost because it charges batteries from solar and grid, prioritises panels during the day, and switches to backup instantly. If you are comparing units, you can buy solar products online and filter by continuous wattage rather than the flashy peak rating that marketing loves to advertise.
Step 3: Size the Battery Bank for Your Outage Window
Battery sizing answers one question: how many hours must you run without sun or grid? For load shedding, plan for the longest realistic cut plus overnight.
Take your daily backup energy and divide by battery depth of discharge (DoD). Lithium LiFePO4 batteries safely use about 90 percent of capacity; lead-acid tolerates only 50 percent before damage.
| Battery type | Usable DoD | Needed for 5.6 kWh | Cycle life |
|---|---|---|---|
| Lead-acid (tubular) | 50% | ~11.2 kWh rated | 1,000–1,500 |
| Lithium LiFePO4 | 90% | ~6.2 kWh rated | 4,000–6,000 |
Lithium costs more upfront but its longer cycle life and higher usable depth make its cost per delivered kilowatt-hour lower over ten years. For most homes covering a full night, a 5 to 6 kWh lithium bank is the sweet spot in 2026.
Step 4: Size the Solar Array to Recharge Fast
Panels must do two jobs at once: run daytime loads and refill the battery before the sun sets. In Kohat and most of Pakistan you can count on roughly 4.5 to 5 peak sun hours per day.
To replace 5.6 kWh plus daytime use, aim for an array that generates around 7 to 8 kWh daily after losses. That points to roughly 1.8 to 2 kW of panels. Add a margin for cloudy winter days and dust, and a 2.5 kW array becomes a comfortable target.
- Six 550 W panels give about 3.3 kW nameplate.
- After heat, dust, and wiring losses you keep roughly 75 to 80 percent.
- That real-world output easily refills a 5–6 kWh battery on a sunny day.
The U.S. Department of Energy notes that keeping panels clean and correctly tilted can meaningfully raise annual yield, a small habit that protects your sizing calculations (see the U.S. Department of Energy guidance on PV maintenance).
Step 5: Sanity-Check the Whole System Together
A solar system fails when one component throttles the rest. Run this final check before you buy:
- Inverter vs array: inverter continuous rating should be at least 60 percent of panel nameplate.
- Array vs battery: charge current must fit within the battery’s recommended charge rate.
- Battery vs load: discharge current at peak load should stay inside the battery’s rated maximum.
Our example home lands on a 3 kW hybrid inverter, a 2.5 kW array, and a 5.6 kWh lithium bank. Every part supports the others, and load shedding stops being an event you dread.
If the arithmetic feels heavy, it is smart to have quality service providers confirm your numbers before installation. A one-hour review often prevents a costly mismatch. Reputable dealers and the best solar company teams will size against your real load list rather than a generic package.
Frequently Asked Questions
How do I size a solar system for load shedding if my bill changes every month?
Use your highest-consumption month for panel and battery sizing so the system copes with your worst case. For the inverter, ignore the bill entirely and size against simultaneous appliance wattage instead.
Can I start small and expand my solar system later?
Yes. Choose a hybrid inverter rated above your current need and a battery chemistry that allows parallel expansion, such as LiFePO4. You can add panels and battery modules in stages as budget allows.
What size inverter do I need for a basic home during outages?
Most modest homes running lights, fans, a fridge, and electronics do well with a 3 kW hybrid inverter. Add a pump or an inverter AC and you should step up to 5 kW to keep surge headroom safe.
Is lithium really worth it over lead-acid for backup?
For daily load-shedding cycling, yes. Lithium delivers more usable energy per rated kWh and lasts three to four times longer, so its cost per usable cycle is lower despite the higher sticker price.
Conclusion
To size a solar system for load shedding in 2026, work in order: list your loads, size the inverter for peak watts, size the battery for your outage window, then size panels to recharge fast, and finish with a whole-system sanity check. Do the math once and you buy exactly what your home needs, no more and no less. When you are ready to shortlist gear, compare continuous ratings and usable battery capacity, and lean on trusted local experts to lock in a system that runs quietly through every cut.
