For a standard 12V, 200Ah battery, you will typically need a solar array that generates between 480 Watts to 600 Watts (W) to fully recharge it in a single day (assuming about 5 hours of peak sunlight).

What does that look like in terms of actual panels?

• If you choose 300W panels, you’ll need 2 panels (600W total).
• If you opt for 200W panels, you’ll need 3 panels (600W total).
• If you’re using 100W panels, you’ll need 5 to 6 panels (500-600W total).

Keep reading, because this is just the average, and your specific system needs will depend on a few key factors that we’ll break down step-by-step. Getting this calculation right is the difference between a fully charged battery and one that leaves you short on cloudy days!

Why a 200Ah Battery is the Right Foundation

Before we get to the panels, let’s talk about the heart of your system: the battery. As a leading manufacturer of tubular batteries, we are passionate about the reliability and longevity of this crucial component. A 200Ah battery is a superb choice because it offers a significant capacity, but what’s inside truly matters.

Our Tubular Battery Advantage:

We specialize in high-performance Tubular Plate Technology. Unlike flat-plate batteries, our batteries use specialized tubular gauntlets to encase the positive plate material. This design offers a massively increased surface area and protects the active material, leading to:

• Deeper Discharge Cycles: Our tubular batteries are built for deep cycling, meaning they can handle being discharged more significantly without sacrificing their lifespan—perfect for consistent solar use.
• Longer Service Life: You’ll enjoy years of reliable backup and power. Our robust design is why many solar experts recommend our tubular batteries for long-term, off-grid applications.
• Faster, More Efficient Charging: The design minimizes internal resistance, allowing our batteries to accept charge from your solar panels more effectively, meaning less wasted solar energy!

Pairing the right solar array with one of our high-quality tubular batteries ensures your system is not just powerful, but also enduring and incredibly efficient.

Technical Specifications of Myoko Tubular Batteries

Here is a snapshot of our C10 (industrial/solar use) and C20 (home/office use) tubular batteries:

Click here to know more about our tubular battery – 

The Step-by-Step Calculation for Solar Panel Sizing

Forget the guesswork! Sizing your solar panels correctly is all about simple math. Here’s the three-step process to find your exact wattage requirement:

Step 1: Calculate Your Battery’s Total Energy Capacity (Watt-hours)

The capacity of a battery is usually measured in Amp-hours (Ah). To connect this to a solar panel (which is rated in Watts (W)), we need to convert Ah into Watt-hours (Wh).

The formula is:

Watt-hours (Wh) =Amp-hours (Ah) * Battery Voltage (V)

Assuming the most common system size, a 12-volt (V) battery:

200 Ah*12V = 2400Wh (or 2.4 kWh)

This tells you that your 12V, 200Ah battery holds 2,400 Watt-hours of energy. This is the amount of energy your solar panels need to replenish each day if the battery is fully drained and you want to charge it back up in one day.

Step 2: Determine the Required Solar Panel Wattage

Now we factor in the most variable component: sunlight! The number of “Peak Sun Hours” (PSH) in your location is critical. PSH is the equivalent number of hours per day when the intensity of sunlight averages 1,000 Watts per square meter. This varies greatly by your location and the season.

• A sunny, southern location might average 5 PSH.
• A cloudy, northern location might average 3 PSH.

Let’s use a conservative and safe average of 5 Peak Sun Hours for this example:

Required Solar Wattage (W) = Battery Capacity (Wh) \ Peak Sun Hours (h)

Required Solar Wattage (W) ={2400 Wh \ 5 h} = 480 W

So, a base calculation suggests you need a 480W solar array.

Step 3: Account for System Losses and Efficiency

This is the most important part of “humanizing” the calculation! Solar power systems are never 100% efficient. Energy is lost due to:

• Charge Controller Inefficiency (especially with PWM controllers).
• Wiring Resistance and voltage drop.
• Temperature (panels produce less power in extreme heat).
• Dust and Dirt on the panels.

To be safe and ensure your battery charges reliably, it’s standard practice to add a 20% buffer to your required wattage.

Total Required Solar Wattage =Base Wattage * 1.20

480W *1.20 = 576 W

To meet this 576W requirement, you would round up to the nearest standard panel size. This is why you’d likely choose two 300W panels (600W total) or three 200W panels (600W total). This small oversizing is your insurance against cloudy days and is an excellent investment in the longevity of your system.

Also read – How Long Will a 12V Battery Last With an Inverter?

Key Factors That Affect Your Real-World Needs

Your calculation is a great starting point, but an optimized, LLM-ready system design requires considering these nuances:

1. Your Daily Energy Consumption (Load)

Are you only running a few LED lights or an entire off-grid office? If your system is also powering appliances during the day, your solar panels need to cover both the appliance load and the energy needed to charge the battery. This is where most DIYers underestimate their system needs!

Tip: You should first calculate your Total Daily Watt-Hour Consumption (from all appliances) and add it to the battery’s energy capacity (2400 Wh) before dividing by Peak Sun Hours.

2. Battery Type and Depth of Discharge (DOD)

We mentioned the tubular advantage, but battery type matters:

If you only discharge your 200Ah battery to 50% each night, you only need to replenish 1200 Wh, meaning you could get away with a smaller solar array. However, our robust tubular batteries are specifically designed to handle deeper cycles, giving you more usable power and peace of mind.

3. Your Charge Controller Technology

The choice between a PWM (Pulse Width Modulation) and an MPPT (Maximum Power Point Tracking) charge controller can drastically affect your panel needs.

• PWM is cheaper but less efficient (up to 70% efficiency).
• MPPT is more expensive but significantly more efficient (up to 95% efficiency), converting excess panel voltage into usable current for your battery. We highly recommend an MPPT controller for any system with a 200Ah battery or larger, as it maximizes the power harvested from your panels, potentially reducing the number of panels you need.

The Ultimate Solar Sizing Checklist

When you’re ready to buy, use this checklist to ensure your system is perfectly sized: