Introduction

Renewable sources of energy (green energy) are currently the main focus of the research of engineers.

It is now a common belief that our planet has finite resources and that we must act thinking about the future of the new generations. Primary objectives must be energy-saving and the limitation of polluting emissions.

The efficiency of the Wind and Solar photovoltaic systems is a crucial aspect to realize robust, safe, and long-lasting solutions. And the good cooling of the inverters is, once again, the “secret” of success.

Priatherm’s team has been at the forefront of developing cooling solutions dedicated to this world for years.

Application field

Sunlight is captured by solar modules, properly positioned on mounting racks to maximize exposure. Solar energy enters the system as Direct Current, which is transferred to a DC/AC inverter. In this process, the current passes through a series of IGBTs.
In photovoltaic applications, IGBTs’ performances are not as demanding as windmills due to the more regular energy flow: in comparison with windmills, the solar plants can provide more predictable and stable energy.
The essential parameters for a good solar system are:
  • the compactness of the heat sink
  • its efficiency (including the possibility of using quiet ventilation) and, in particular,
  • its cost-benefit ratio
The customer was looking for a high-level air-cooled heat sink in forced convection (more detailed information at our dedicated article), with the possibility of dissipating several hundreds of Watts, in heat sinks no larger than 250x400x100 mm and with competitive production costs.
Priatherm has been selected as the best partner to develop this design and its subsequent evolution (increase in power, without upsetting the geometries too much).

The challenge

The customer’s goal was to push on the market a three-phase string inverter with the following characteristics:

  • Max efficiency
  • High robustness and flexibility
  • Easy installation
  • Safe
  • Smart
  • Remote control and maintenance

The choice of the heatsink was by no means trivial due to the competitive cost specifications, small size, and flexibility in increasing performance without additional investments in production equipment.

Solution

The project has been developed in two steps.
  1. Initially with a compact Brazed fin (PT High) – 225x300x100 mm, with 44 fins – 3000 W have been dissipated. Three heatsinks in parallel were able to realize one of the most competitive solar solutions in the world. The customer was able to win tenders in North Africa, Central America, and South America.
  2. Later, the customer decided to make an upgrade of its machine and brought the Power to dissipate to 4000 W per module.
Priatherm, using the same Brazing technology and design (44 fins on a 225 mm wide base) achieved the requested performance by increasing the total length of the heatsink up to 375 mm.
By using Brazing technology, that was possible to design, several advantages have been pursued:
  • High-performing heatsink: given the metal joint between base and fins, no air gap, no barriers to thermal conductivity
  • Compact design: thanks to the high fin ratio, not achievable with the standard extrusion process
  • Cost-effective: with a simple design, fast to assembly
The additional benefit of this idea was the possibility to increase the performance and Upgrade the customer inverter with a higher power, without additional tooling costs. Using the same raw material and manufacturing process, but modifying dimensions, a new challenging goal was reached.

Top challenges

  • High performance vs compact dimensions
  • Researching a solution with the best ratio “benefit vs cost”
  • Scalability of the design (increasing power) without additional tooling costs

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