PWM vs. TrakStar MPPT Technology

Traditional PWM vs Morningstar’s TrakStar™ MPPT Technology
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Maximizing MPPT Boost with a Morningstar MPPT Controller:
Morningstar’s patented TrakStar MPPT technology sets itself apart from other less effective MPPT
solar controllers on the market. Because of the following advantages Morningstar maintains
consistently better output power which translates into more MPPT Boost:
• Consistently higher efficiencies under all operating conditions
• Lower self-consumption power losses
• No fans (lower efficiency power losses get turned into heat so fans are needed to
use up
additional charging power)
• Staying on Track. (Operates at MPPT levels more of the time)
This additional energy translates into a more consistently larger MPPT Boost. Given an MPPT
boost of 10%, just 1% higher efficiency would mean 10% more MPPT boost.
PWM Over MPPT:
The preceding discussion of PWM vs. MPPT may cause some to wonder why a PWM controller would
ever be chosen in favor of an MPPT controller. There are indeed instances where a PWM controller can
be a better choice than MPPT and there are factors which will reduce or negate the advantages the
MPPT may provide. The most obvious consideration is cost. MPPT controllers tend to cost more than
their PWM counterparts. When deciding on a controller, the extra cost of MPPT should be analyzed
with respect to the following factors:
1. Low power (specifically low current) charging applications may have equal or better energy harvest
with a PWM controller. PWM controllers will operate at a relatively constant harvesting efficiency
regardless of the size of the system (all things being equal, efficiency will be the same whether using
a 30W array or a 300W array). MPPT regulators commonly have noticeably reduced harvesting
efficiencies (relative to their peak efficiency) when used in low power applications. Efficiency
curves for every Morningstar MPPT controller are printed in their corresponding manuals and
should be reviewed when making a regulator decision. (Manuals are available for download on the
Morningstar website).
2. As explained in the Environmental Considerations section, the greatest benefit of an MPPT regulator
will be observed in colder climates (V
mp is higher). Conversely, in hotter climates Vmp is reduced.
A decrease in V
mp will reduce MPPT harvest relative to PWM. Average ambient temperature at the
installation site may be high enough to negate any charging advantages the MPPT has over the