Solar Panels MPPT: What is Maximum Power Point Tracking?

While perusing the internet for information on solar installations, you might have run across the term maximum power point tracking, or MPPT, and wondered what it means. Solar installers, designers, and sales people throw around this term quite a bit and everyone knows it’s important, but few in the industry actually understand what it is exactly. This is with good reason – it’s kind of complicated.

For homeowners interested in solar, it helps to know the basics of MPPT, what it is and how it fits into a solar installation, so you can make sure you’re getting the most benefit from your installation.

So What Exactly is Maximum Power Point Tracking (MPPT)?

At its most basic, MPPT is simply helps your solar panels produce more power.

All solar panels have a maximum power point (MPP), which is the optimal conditions where they produce the most electricity. This MPP is affected by both the immediate environment like temperature and shading as well as irradiance levels (the amount of solar radiation that hits the panel). MPPT technology is constantly watching, or tracking, the panels’ MPP and then tweaking the panels output to optimize performance.

Sounds pretty cool right? It is! MPPT can increase a solar installation’s production upwards of 40%! You certainly wouldn’t want to be caught without it!

Does My Solar Array Have MPPT?

Most solar installations these days have MPPT somewhere in the system.

Solar systems are composed of many solar panels connected together to form what’s called an ‘array’. The array is connected to the inverter, which changes the electricity from the direct current created by the panels to the alternating current used by the utility grid.

For grid-tied solar systems, MPPT is typically imbedded in the inverter, so it can assess and optimize the electricity coming from the panels. If the system didn’t have MPPT, the solar panels wouldn’t be performing at their best!

Inverters typically have a single MPPT, which works well when all the panels are facing the same direction and tilted at the same angle. However, if the solar installation is on two different sections of a roof and the two arrays are facing different directions, a single MPPT inverter isn’t a great option – as it can’t optimize the current/voltage mix for the two different situations. In this case, a dual MPPT inverter is often a better option. The two arrays would enter the inverter separately and each would have its own MPPT that optimizes the groups independently. This is becoming increasingly common among residential installations.

Instead of a dual MPPT inverter, some homeowners simply forgo this issue and install microinverters instead, which optimize each solar panel individually, so there’s no need for all the solar panels to have the same direction and tilt.

For off-grid systems, MPPT is usually incorporated into the charge controller, which regulates current and voltage coming from the solar panels so the batteries aren’t overcharged.

How Does MPPT work?

We’ve seen how MPPT makes solar installations even better. Now let’s get into the details of how MPPT works.

When the sun is shining and your solar panels are producing electricity, that electricity can be measured in both voltage (measured in volts) and current (measured in amps).

Remember MPP? A solar panel’s MPP is when voltage and current are balanced appropriately. Sometimes though, environmental changes like extremely hot weather create situations where the solar panels can’t perform at their MPP. To alleviate this issue, MPPT is able to balance voltage and current by increasing one, current for instance, and decreasing the other (voltage).

This is especially important for off-grid systems with batteries, as most solar batteries are 12 volts, but actually fluctuate between 10.5 and 12.5 volts throughout the day as they are discharged and appliances are turned on and off. To charge the batteries, the solar panels must produce electricity with a higher voltage that the batteries. If it’s a lower voltage, the batteries won’t charge. MPPT balances the voltage and current, increasing the voltage if need be, so the voltage the panels produce is just above the batteries’ voltage, allowing the batteries to charge.

What Are the Benefits of MPPT?

As we’ve seen, MPPT allows your solar system to operate more efficiently. In the winter months, efficiency can increase as much as 40%! The MPPT allows your solar panels to perform at their max as much as possible – giving you more renewable electricity. Without MPPT, your solar installation’s output would be much lower. By increasing your energy production, MPPT shortens your return on investment and makes your system even more cost-effective. Many homeowners likely don’t even know they have MPPT, but they see the benefits every day!