How to Calculate Your Off-Grid Solar Load

Off-grid solar power isn’t just about panels. It’s about ensuring your energy system matches your real-life energy needs every hour of every day.

Here in Columbus, where storms and outages aren’t just hypotheticals, calculating your solar load correctly can mean the difference between independence and inconvenience.

Let’s break down how to do it the right way.

Step 1: List Every Appliance You Want to Power

Think about what needs to stay running when you're off-grid. Include:

• Fridge and freezer

• Lights (and how many)

• Water pump (if applicable)

• Internet and router

• TVs or computers

• Furnace fans or AC units (if critical)

• Washer, dryer, microwave (if used off-grid)

💡 Pro Tip from Brian at BC Solar: Don’t just list what’s nice to have. Prioritize what’s essential, especially during grid failures.

Step 2: Find Out Each Appliance’s Wattage

This info is usually listed on a label near the plug or in the manual. If not, look it up online.

Then multiply:
Watts x Hours of Use per Day = Watt-Hours (Wh) per Day

Example:

• LED Light (10W) used 5 hours = 50Wh

• Fridge (120W) used 24 hours = 2,880Wh

Do this for each appliance.

Step 3: Add Up Your Total Daily Load

Add all your Wh/day numbers together.

Example:

• Lights: 200Wh

• Fridge: 2,880Wh

• Internet: 300Wh

• TV: 400Wh
  Total = 3,780Wh/day

Step 4: Add a Safety Margin

It’s smart to add 20-30% to account for:

• Inverter losses

• Battery inefficiencies

• Seasonal changes

• Expansion later

So for 3,780Wh/day:

• 30% safety margin = 1,134Wh

• Total load = ~4,900Wh/day

Step 5: Size Your Battery Bank

This depends on how many days of backup you want. Let’s say 2 days:

• 4,900Wh/day x 2 = 9,800Wh or 9.8kWh

If you’re using 48V batteries:

• 9,800Wh ÷ 48V = ~204Ah (amp-hours)

Choose batteries that can provide at least that ideally more if you want extended autonomy during cloudy periods.

Step 6: Size Your Solar Array

Take your daily load and divide by average sun hours per day in Ohio (~4 hours):

• 4,900Wh ÷ 4 sun hours = 1,225W solar array minimum

But we recommend:

• 1,500W to 2,000W to allow for charging batteries fully and accounting for cloudy days.

BC Solar’s Advice

At BC Solar, we design off-grid systems in Columbus and nearby areas with:

• Sol-Ark hybrid inverters

• Battery-first designs

• Options to charge from grid or generator if needed

• Transparent planning and load analysis based on real usage

We help you not only stay online when the grid is down but thrive.

FAQs

How much solar do I need to live off-grid in Columbus?
It depends on your daily electricity usage. Most off-grid homes require at least 5kWh/day and 1.5–2kW of panels more if you want to run AC, laundry, or electric heating.

Can I go off-grid without batteries?
No. Batteries are the heart of an off-grid system. They store energy for night and cloudy days.

What happens if my usage exceeds the load?
Your system shuts down or your batteries go flat. That’s why calculating correctly and oversizing slightly is critical.

Do you install off-grid systems year-round in Columbus?
Yes. We serve homes, cabins, and commercial sites across Central Ohio with off-grid and hybrid solar solutions.

Have questions or want your load professionally calculated?

Call BC Solar today: (614) 442-9700
Visit: https://bc.solar