How Much Solar Do You Really Need?

One of the most common questions I get is:

“How much solar should I put on my van, RV, or trailer?”

And my answer usually surprises people—because it’s not what they expect.

I often say:
“Get as much solar as you can afford and physically fit.”

But here’s the truth—that’s not actually the right question.

The Real Question Isn’t About Solar

Most people start their system design thinking about solar panels first. That’s backwards.

Your system does not run on solar.

It runs on battery power.

When you’re off-grid—at night, in bad weather, or parked in the shade—your solar panels aren’t doing anything. Your entire system depends on stored energy in your batteries. Solar panels simply recharge those batteries when the sun is out.

And even in ideal conditions, you’re only getting about 5–6 peak sun hours per day.

How a Solar System Actually Works

• Battery = your fuel tank
• Solar panels = your refueling source
• Inverter = what makes the power usable

If your “fuel tank” is too small, it doesn’t matter how fast you refill it—you’ll constantly run out.

Start With Battery, Not Panels

So now, my answer has evolved into something much more accurate:

“Get as much battery capacity as you can afford and fit—and then size your solar to recharge it.”

Your battery bank determines:

• How long you can stay off-grid
• How much power you can use daily
• Whether your system feels reliable—or constantly stressed

👉 Start with high-quality LiFePO4 batteries here:

https://solarsupplyhouse.com/collections/lifepo4-cells-and-batteries

Step One: Do a Real Power Audit

Before you buy anything, you need to understand your actual power usage.

A proper power audit includes everything you plan to run:

• Refrigerator
• Lights
• Fans
• Water pump
• Electronics (laptops, Starlink, TVs)
• Inverter loads (microwave, coffee maker, etc.)

Start With Your Biggest Load

Your largest power draw is usually refrigeration, because it runs 24/7.

Example:

50 watts × 24 hours = 1,200 Wh per day

That’s your baseline. From there, you add your other loads.

Example Daily Power Breakdown

• Fridge: 1,200 Wh
• Lights: 150 Wh
• Fan: 300 Wh
• Devices: 300 Wh

Total: ~2,000 Wh per day

Build Your Battery Around Your Usage

If you use 2,000 Wh/day and want 2 days of autonomy:

2,000 × 2 = 4,000 Wh battery (4 kWh)

This is where quality matters most.

👉 Explore LiFePO4 battery options here:

Shop Batteries

Now Size Your Solar to Match

If you use 2,000 Wh/day and get ~5 hours of sun:

2,000 ÷ 5 = 400W minimum solar

But real-world conditions require more:

• Cloud cover
• Heat losses
• Panel angle
• Dirt/shading

Realistic recommendation: 600–800W solar

Why This Approach Saves You Money

• Avoid undersized systems
• Prevent costly upgrades
• Improve reliability
• Reduce long-term cost

Designing around battery first means your system works in real-world conditions—not just on paper.

The Bottom Line

Solar panels don’t power your system—they support it.

Your battery is what keeps everything running.

So instead of asking:

“How much solar do I need?”

Ask:

• How much power do I use?
• How long do I want to stay off-grid?
• How much battery do I need?

Then size your solar to match.

Final Thought

The best systems aren’t the biggest—they’re the ones designed correctly from the start.

If you build around your battery and your real-world usage, you won’t just save money—you’ll avoid rebuilding your system later.