Solar Load Calculator
Add up what you actually run, appliance by appliance, and see where your electricity goes. No bill needed – which makes this the place to start if you are building, moving, planning backup, or simply want to know why your bill looks the way it does.
How much electricity do you actually use?
Appliance by appliance, no bill needed.
Typical figures cover most Pakistani households. Switch to manual entry if you have the wattage printed on the appliance, which gives a more accurate answer.
Add the appliances you run, and how many hours a day each one is on.
Why start from appliances instead of your bill
Your bill tells you how much electricity you used. It does not tell you what used it.
That distinction matters more than it sounds. Two households both using 650 units a month can need completely different systems — one running an air conditioner eight hours a day has a very different load shape from one running fans and a water pump. Sizing from the total alone hides that.
Working from appliances also answers questions a bill cannot:
You do not have a bill yet. New construction, a new connection, or a property you have not moved into.
You are planning backup rather than bill reduction. Backup sizing depends on what has to stay on during an outage, not on your monthly total.
You want to know what to change. A monthly figure gives you nothing to act on. A breakdown showing that one appliance is 44% of your consumption gives you something you can do tomorrow.
Connected load is not your real demand
The calculator gives you two different power figures, and confusing them is the most common sizing mistake.
Connected load is the sum of everything, as though it all switched on at the same instant. A household with ten lights, five fans, a fridge, an air conditioner, a pump, an iron and a washing machine has a connected load of roughly 4,400 watts.
Actual demand is what runs at any given moment, and it is always lower. You do not iron while the washing machine is running while the pump is on. In practice most homes peak at somewhere between a third and a half of their connected load.
Use each for what it is for. Connected load is the ceiling – useful when sizing an inverter, because it tells you the worst case you could theoretically ask it to carry. Daily kilowatt-hours is what sizes your solar array and your battery, because that is energy rather than instantaneous power.
The wattages this calculator uses
Every figure below is a typical running wattage, not a nameplate peak. The refrigerator is counted at its average draw across the compressor duty cycle rather than the moment it kicks in, because that is what determines energy over a day.
Appliance | Typical running watts | Typical hours/day |
|---|---|---|
WiFi router | 10 | 24 |
LED lights (each) | 12 | 6 |
Pedestal fan | 60 | 8 |
Ceiling fan | 75 | 12 |
LED TV | 100 | 5 |
Water dispenser | 100 | 8 |
Refrigerator | 150 | 24 |
Computer / laptop | 150 | 6 |
Deep freezer | 200 | 24 |
Air cooler | 200 | 8 |
Washing machine | 500 | 1 |
Water pump | 750 | 1 |
1-ton inverter AC | 1200 | 8 |
Iron | 1000 | 0.5 |
1.5-ton inverter AC | 1800 | 8 |
Microwave | 2000 | 0.5 |
The hours are editable defaults, not fixed assumptions. Change them to match how you actually live – the difference between running an air conditioner six hours and ten is larger than most other decisions on this page.
One appliance usually decides your bill
Run the numbers on a typical Lahore household – ten lights, five fans, a television, a fridge, one 1.5-ton inverter AC, a washing machine, a pump, an iron, a laptop and a router – and it comes to about 21.8 kWh a day, or roughly 650 units a month.
Of that, the air conditioner alone is about 44%. The five ceiling fans together are 21%. The fridge is 17%. Everything else combined – television, laptop, washing machine, pump, iron, router, all ten lights – accounts for less than a fifth.
This is why generic advice about switching off lights is close to useless in a Pakistani summer. The lights are not the problem. One appliance is, and the calculator names it for you.
Two things follow. First, if you want a smaller bill, the shortest route is to change how the largest load runs – not to economise across everything else. Second, if you are going solar, that same load is what your system is really being built to cover, and the more of its running hours you can move into daylight, the better your economics get.
The number that is not on this page
Surge.
Motors do not start gently. An air conditioner compressor, a water pump and a refrigerator all draw several times their running wattage for the first fraction of a second after switching on. A 750-watt pump can momentarily pull two to three thousand watts.
This calculator deliberately does not model it, because surge depends on the specific motor and the specific unit, and a made-up multiplier would be worse than an honest gap. But it matters in two places:
Your inverter has to survive it. An inverter sized only to your running load will trip when the pump and the air conditioner start together. Inverters publish a separate surge rating for exactly this reason.
Your battery has to deliver it. A bank correct on energy can still fail on instantaneous current if it is asked to start a heavy motor.
So treat the connected load figure here as your starting point for inverter sizing, then leave headroom on top of it.
Next step
You now have a monthly figure built from what you actually run, rather than from an average. That is the input every other calculator on this site wants.