Guide to Solar Panels & Charging

Here’s a detailed overview of how a 200W solar panel can charge a 12V battery system in a car, caravan, or boat, along with an example.

Allspark 200w Solar Panel

Here is the information you will see on the back of a solar panel.

Dimensions (LxWxH mm) - 1500 x 680 x 35

Maximum power (Pmax) - 200w

Open-circuit voltage (Voc) - 24v

There is lots of additional information on the back of a solar panel, But for basic purposes, This is the information you generally need to get an idea of how much power this will produce and when considering this against the power consumption used by your fridges and other accessories will give you an idea if your solar panel will keep your battery charged in good sun.

your battery system is 12 volt

The solar panel pictured is 200w

Divide the wattage by the system voltage (200/12 = 16.6a)

When you lay a panel flat ontop of a camper, car or caravan, The general math is you should only expect to see 80% of this power.

16.6a * 0.8 = 13.3a

This is the figure you should expect to see hourly in good sun

Multiply this figure by 6x to account for 6 hours of good sun per day

13.3a x 6hours = 80ah of charge per day

Solar Charging Basics:

• A solar panel converts sunlight into electrical energy
• The 200W solar panel generates electricity based on sunlight availability, which can be used to charge a 12V battery.
• Typically, the solar panel is connected to a charge controller, which regulates the voltage and current going to the battery, ensuring safe charging.

Components Involved:

1. Solar Panel: Converts solar energy to electricity.
2. Charge Controller: Protects the battery from overcharging and regulates the charging process.
3. Battery: Stores the energy for later use.
4. Inverter (if needed): Converts DC to AC for appliances.

Charging Calculation Example

Let’s assume you have a 200W solar panel and a 12V lithium battery system with a 100Ah capacity.

Step 1: Daily Energy Generation

• Peak Sun Hours: The amount of sunlight varies, but a common estimate for peak sun hours is about 5 hours per day (this can vary based on location and season).

• Daily Energy Generation:

  $$\text{Daily Energy (Wh)} = \text{Panel Wattage} \times \text{Peak Sun Hours}$$ $$\text{Daily Energy} = 200W \times 5h = 1000Wh$$

Step 2: Daily Charging

• Convert Wh to Ah: $$\text{Daily Charging (Ah)} = \frac{\text{Daily Energy (Wh)}}{12V}$$ $$\text{Daily Charging} = \frac{1000Wh}{12V} \approx 83.33Ah$$

Step 3: Charging the Battery

With a 100Ah battery, charging it with 83.33Ah in one day means you could fully recharge it if it were depleted (assuming 100% efficiency, which is ideal).

Example Scenario

Scenario: Boat with a 200W Solar Panel

1. Boat Configuration: 200W solar panel connected to a 100Ah, 12V lithium battery.
2. Location: Mooring in an area with good sun exposure, averaging about 5 peak sun hours per day.

Daily Charging Potential:

• Total Daily Charge: 83.33Ah (as calculated above).
• If the battery was at 50% (50Ah), the solar panel could fully recharge it in one day.

Considerations:

• Efficiency Losses: Real-world factors (charge controller losses, battery efficiency, shading, etc.) might reduce the effective charging capacity. Assume around 80% efficiency. $$\text{Effective Daily Charging} \approx 83.33Ah \times 0.8 \approx 66.67Ah$$

In this case, if the battery was at 50%, it would take about 1 day of good sunlight to fully recharge.

Summary

A 200W solar panel can effectively charge a 12V battery system, providing a sustainable power source for applications in cars, caravans, or boats. With proper setup and considerations for efficiency, it can significantly extend the usability of your battery system without relying on external power sources.