Adding New Solar Panels to an Existing System

Do you need to generate more power from your existing solar setup?

The best thing to do is to add the exact same panel model with the same voltage and current specs. The wattage of the panel is almost irrelevant – in other words, you can’t just connect a newer model 100-watt panel to an older one, because most likely the voltage and current will be different, which means the system will suffer from power losses.

But sometimes you will find that the exact same panel isn’t sold anymore. This happens a lot as solar panels are frequently upgraded to take advantage of newer tech. That’s why at LUX Solar we recommend thinking about whether you will want to upgrade when you design your first solar system.

Understand Your Current System

Before adding a new solar panel, it's essential to understand the key specifications of your existing setup – most importantly, Voltage and Current Ratings: Each solar panel has specific voltage (Vmp) and current (Imp) ratings.

1. Using Separate Charge Controllers

The easiest way to avoid compatibility issues is to use separate solar charge controllers for each panel attached to the same battery bank. This can be a cost and time-effective solution if the voltage and current characteristics of panels do not match.

2. Wiring in Parallel

If you find a solar panel with a matching voltage (Vmp) to your existing panels, you can wire them in parallel. This method is beneficial for maintaining system voltage while increasing current output.

Approximate Power Losses: If the voltage differs between the two panels, calculate the losses using the formula:

3. Wiring in Series

If you find a solar panel that matches the current (Imp) of your existing panels, you can wire them in series. This configuration allows the system to increase voltage while maintaining the same current.

Approximate Power Losses: If the current values differ, you can calculate the power loss with the following formula:

Mixed Panel Power Loss Calculator