Before You Buy That Solar Panel — Read This Solar Sizing Guide First!
So, you’ve finally decided to go solar. That’s a smart move — but before you rush to buy panels or batteries, take a pause. The truth is, buying solar equipment without proper sizing is like buying clothes without knowing your size — it might look great, but it won’t fit your needs.
Every successful solar installation starts with one essential step: solar sizing. And if you skip it, you’ll likely end up spending more money on a system that underperforms or fails prematurely.
In this guide, we’ll break down the secrets of accurate solar sizing, how to calculate your energy needs, and how the Globisun Solar Sizing App can do all the heavy lifting for you in seconds.
⚡ Why Solar Sizing Matters More Than You Think
Here’s a little-known fact: most people in Nigeria who complain that “solar doesn’t work” actually have systems that were improperly sized.
Solar sizing means calculating exactly how much power you use, then designing your solar system (panels, batteries, inverter, and charge controller) to meet that demand efficiently.
If your system is undersized, it won’t power your home for long.
If it’s oversized, you’ll waste money on unnecessary equipment.
Proper solar system design ensures:
- Your batteries last longer
- Your inverter doesn’t overload
- Your solar panels generate enough power daily
- And most importantly — your lights stay on, always!
You can easily calculate your solar needs using the Globisun app without needing a degree in electrical engineering.
🔋 Step 1: Know Your Energy Consumption
Before anything else, you need to calculate how much electricity you use daily — that’s your total load.
Here’s how to do a simple load calculation:
Total Load (Wh) = Power of each appliance (W) × Hours used per day
Example:
| Appliance | Power (W) | Hours/day | Energy (Wh) |
|---|---|---|---|
| TV | 100 | 5 | 500 |
| Fan | 80 | 8 | 640 |
| Bulb (x4) | 15 | 6 | 360 |
| Freezer | 120 | 10 | 1200 |
| Total | 2,700 Wh or 2.7 kWh/day |
That means your home consumes about 2.7kWh of energy per day.
⚙️ Step 2: Size Your Solar Panels
Now that you know your daily energy demand, you can estimate how many panels you’ll need.
Formula:
Solar panel size (W) = (Total load × 1.3) ÷ Average sunlight hours
If you get 5 hours of sunlight daily:
(2,700 × 1.3) ÷ 5 = 702W
You’ll need about 3 panels of 300W each.
Or better still, open the Globisun Solar Sizing App, enter your load, and let it do the solar panel calculation automatically — no math needed!
🔋 Step 3: Size Your Batteries
Your batteries store the energy your panels generate. So you’ll want enough capacity to last through the night or cloudy days.
Formula:
Battery capacity (Ah) = (Total load ÷ system voltage) ÷ depth of discharge
For a 12V system:
(2,700 ÷ 12) ÷ 0.8 = 281Ah
You’ll need about two 150Ah batteries for a full day’s power.
The Globisun Solar App also gives you the ideal battery size and number automatically once you input your total load.
⚙️ Step 4: Size Your Inverter
Your inverter must be powerful enough to handle your total load at once.
Formula:
Inverter size (VA) = Total load (W) ÷ Power factor (≈ 0.8)
For a 1,500W load:
1,500 ÷ 0.8 = 1,875VA, round up to a 2kVA inverter.
Undersizing your inverter will make it trip frequently. Oversizing it wastes money. The Globisun App tells you the perfect inverter match automatically.
🔌 Step 5: Don’t Forget Your Charge Controller & Cables
A charge controller regulates the current flowing from your panels to your batteries. If it’s too small, your batteries could get damaged.
Formula:
Controller size (A) = Total panel wattage ÷ System voltage
For 900W panels on a 12V system:
900 ÷ 12 = 75A, so you need a 75A charge controller.
And as for cables — always use the right size to avoid energy loss and overheating. The Globisun Solar Sizing App even suggests the ideal cable size for each setup.
🤖 The Easy Way — Use the Globisun App
Let’s be honest: doing all these calculations manually is stressful.
That’s why professionals now rely on smart digital tools like the Globisun Solar Sizing App — a mobile tool that helps you:
✅ Calculate your load requirements
✅ Size your panels, inverter, and batteries correctly
✅ Get cable and charge controller recommendations
✅ View daily solar weather forecasts
✅ Design your solar system like a pro — in minutes
It’s accurate, easy to use, and completely free to download on the Play Store.
🌞 Final Thoughts — Buy Smart, Not Blind
Solar is one of the best investments you can make — but only if you size it right. Don’t let an installer guess your system capacity or sell you unnecessary components.
Instead, know your numbers. Use the Globisun Solar Sizing App to calculate your needs accurately and make informed buying decisions.
Before you buy that solar panel — run the numbers first.
⚡ Download the Globisun App today and take the guesswork out of your solar installation!
