Merchant Power Supplies: It's Still Better to Buy

­Verified market reports show the merchant power supply market was valued at USD 33.78 billion in 2021 and is projected to reach USD 50.22 billion by 2030 -- a CAGR of 5.13%. This growing market has evolved since the early 2000s. Back then, I wrote a “make vs. buy” article, saying it was better to buy merchant power supplies for each project than designing them yourself. Since then, buying off-the-shelf makes even more sense. Instead of commissioning a power supply from one of the dwindling number of custom power supply design houses -- you can buy and build what you want out of standard building blocks.

Merchant power conversion companies, globally, have kept up with advanced technologies in WBG devices, innovative magnetics designs and more. Moreover, power supply technologies have developed to meet today’s much stricter and more numerous industry standards. For example, we now have 60601-4th edition EMC and even tighter requirements in the industrial and computing market. And the latest 60601 medical and 62368 requirements were either not in existence or were not as stringent way back when. Additionally, we have requirements for SEMI-F47 hold-up times, 5000 meters altitude with no derating, and 300 volts AC applied for some period without damage due to poor power regulation. Plus, there’s the “bouncy” nature of the grid in developing countries. Then add shock and vibration to MIL STD 810G, or sometimes even railway standards, efficiency standards for both standby and operating conditions, power factor correction mandates and more.

I recently was involved in a project where a battery charging system was needed to keep both 12- and 24-volt sealed gel batteries charged and ready to take over if power fails. The project selected recently released power supplies that had built-in, 4-stage battery charge conditioning. The units were sealed and potted to survive hostile outdoor environments, came with a 5-year warranty and met all the above (other than medical) requirements. Could we have designed this ourselves? Sure, but not as well – and not for the price. Oh, did I mention they were available off the shelf from both Digikey and Mouser? 

Of course, there are still cases where you should design your own power supplies, such as when you have a unique form factor, or your volumes are so high that it makes sense (the electric metering market comes to mind), you’re dealing with space grade or, perhaps, if you simply can’t convince one of the big Taiwan-based companies to do something specifically for you; but in this case, you better make sure you have the skill sets in your organization to pull it off.

Otherwise, it’s still better to buy. The merchant power supply market gives you astounding value and performance at a price per watt level that was unheard of just a few years ago.