I Built a Solar Power System for Winter Field Day… But Almost Made a HUGE Mistake!

You might be wondering—why not just buy a pre-built solar power station like an EcoFlow? There are two main reasons:

• Cost – Pre-built power stations can easily cost over $1,000. I was able to build my entire system for under $500.
• Modularity – With individual components, troubleshooting and replacement are much easier. If a part fails, I can swap it out rather than replacing an entire unit.

Now, let’s walk through the system I built and why I chose these components.

System Components and Design

Solar Input and Protection

The system starts with a 50-amp circuit breaker on the input side. This serves two purposes:

• Provides protection in case of a short circuit.
• Allows me to easily disconnect power for maintenance.

Solar Charge Controller

From there, power goes into a Renogy Wanderer 30A PWM Solar Charge Controller. This controller is capable of handling up to 30 amps, which is more than enough for my 300-watt solar panel setup.

I also added the optional Bluetooth module, which allows me to monitor solar panel performance from my phone.

Battery Bank and Circuit Protection

The charge controller feeds into a terminal block and then a 200-amp circuit breaker that connects directly to the battery bank. This circuit breaker protects the system and provides a convenient way to shut off power when needed.

For batteries, I used two Renogy 100Ah lithium iron phosphate (LiFePO4) batteries connected in parallel.

Important: When connecting batteries in parallel, you need to ensure they have matching voltages. Otherwise, you risk improper charging, reduced power capacity, or even catastrophic failure.

Steps to Safely Connect Batteries in Parallel:

1. Fully charge both batteries.
2. Use a voltmeter to check their voltages.
3. If the voltages are different, balance them before connecting.
4. Once balanced, connect them in parallel to expand capacity.

Power Conversion: Why Use an Inverter?

The battery bank supplies 12.8V DC, but my radios require 13.8V DC for maximum power output. Running power over long distances also introduces voltage drop, which could lead to underpowered radios.

To solve this, I used a 1,000-watt pure sine wave inverter:

• It provides clean AC power to run a 13.8V DC power supply for my radios.
• It eliminates the need to run long DC cables, reducing voltage drop.
• It allows us to power additional AC devices if needed.

Final System Setup

1. Solar panels → 50A circuit breaker → Renogy charge controller
2. Charge controller → 200A circuit breaker → Battery bank
3. Battery bank → Pure sine wave inverter → AC power to radios
4. AC power supply converts back to 13.8V DC for optimal radio performance.

The Step I Almost Forgot

I nearly forgot to properly balance the two batteries before connecting them in parallel. This oversight could have led to inefficient charging, permanent battery damage, or even an explosion due to high inrush currents.

To avoid this:

• Always fully charge each battery separately.
• Measure and match their voltages before connecting them.

Ready for Winter Field Day!

With this solar power setup, I’m confident that we can operate efficiently during Winter Field Day while also preparing for potential grid-down scenarios.

What are your plans for Winter Field Day? Are you running off-grid power?