What you need to know about Solar Panels Specs - Vmp, Moc, ISc and PMAX

Whether you’re setting up solar for your caravan, boat, or that dream off-grid cabin, understanding your solar panel specs is the FIRST step to getting your solar working.   You don’t want to overspend on equipment you don’t need—or accidentally fry your gear. By knowing how to read solar specs, you can:

1. Match your solar panels to charge controllers and batteries
2. Maximize efficiency (get the most from your system!)
3. Avoid system failures and costly mistakes

What are those Numbers on Your Panel?

Every solar panel has a label (usually on the back) or datasheet with all the important details. Here’s what you’ll see and WHY it matters 👇:

 Vmp (Voltage at Maximum Power):

• This is the voltage your panel runs at for the best performance.
• Make sure your charge controller and batteries are compatible with this.

 Imp (Current at Maximum Power):

• This is how much current (amps) the panel produces when it’s working its hardest.
• Needed to size your system wiring and charge controller amp rating.

Voc (Open Circuit Voltage):

• The highest voltage your panel can hit (when it’s not connected).
• Important to check your system can handle it, especially in cold weather (when Voc increases). 

 Isc (Short Circuit Current):

• The max amps the panel can produce in a short circuit.
• Helps size safety components like fuses and breakers.

 Pmax (Maximum Power):

• The total power output in watts.
• Want to know how many panels you need to power your system? Start here!

Where to Find These Numbers

 Look on the back of your solar panel for a sticker (or check the manufacturer’s datasheet online). You’ll see all the key specs laid out.

How to use these number to design your solar

When connecting multiple panels, add voltages in series and add currents in parallel to calculate your total system specs. This is key to making sure your system doesn’t overload. 

You need to Match the rest of your system components (charge controller, batteries, fuses) to be compatible with your solar panel specifications.  

Design smarter: LUX Solar have created a tool to automatically recommend Solar Components that will work with any given array of panels, based on their specifications! 

Visit www.luxsolar.co.nz/pages/lux-solar-anykit to access our AnyKit Solar Design tool.  

Choose from any of LUX Solar's panel range, or add your own custom panels.  LUX AnyKit will automatically calculate how to optimally wire your panels (series or parallel), and recommend which controller and other components you need to get up and running.  

Email technical@luxsolar.co.nz with any further questions!