Build more efficient BESS solutions with silicon carbide power converters

Build more efficient BESS solutions with silicon carbide power converters

I know you’re busy, so let’s get straight to the point: When you’re designing battery energy storage systems (BESS), you can benefit by choosing power converter systems (PCS) with silicon carbide MOSFETS instead of traditional silicon IGBTs. Here’s how:

1. You can reduce energy losses, energy costs, and carbon emissions
2. You can increase energy density and reduce integration and logistics costs
3. You can improve reliability and reduce cost and complexity
4. You can reduce BESS noise

These benefits are possible because PCSes with silicon carbide (SiC) MOSFETs, for example the market-ready DEIF iE Convert range , help you improve efficiency, reduce BESS size and weight, boost power quality, and maximise cooling efficiency.

That’s it – that’s all you need to know. But if you want a little more detail, keep reading. I think you’ll find it worth your while.

Research suggests 3% efficiency gains are possible

Most published vendor datasheets indicate that you can improve efficiency by 1% by switching from silicon IGBTs to SiC MOSFETs. However, calculations done by DEIF based on independent research suggest that PCS efficiency improvements could be as big as 3% which means more useful energy from the same battery.

BESS solutions always include at least two energy conversion stages, and at each stage some electrical energy will unavoidably be lost as heat. Carlos D. Fuentes and colleagues have shown that this energy loss is lower with SiC MOSFETs. In fact, conversion efficiency can be improved by up to 3% at light loads compared to silicon, and that gives you significant BESS energy savings: Very few applications always have continuous high loads. Some variability is to be expected, and this increases efficiency gains.

To give you an idea just how significant these savings are, let’s take a quick example: If you’re building medium-sized 2MWh/1MW C&I BESS assets used for peak shaving and energy arbitrage, and your assets complete two cycles per day, an efficiency improvement of just 1-2% would save your customers more than 60MWh over the course of a year. If we base our example on 2024 average EU energy costs and emission factors, that amounts to €12,000 (USD13,700) in saved electricity costs and carbon emission reductions of more than 20 tonnes.

In complex or utility-scale scenarios, these savings add up because of the high number of duty cycles and the sheer volume of energy processed. But you can achieve efficiency gains in any BESS application, from ships and offshore platforms to C&I, rental, and utility solutions, and thereby reduce energy losses, energy costs, and carbon emissions.

This is great news for your customers and the climate – and it helps you push the boundaries and design high-efficiency BESS solutions that give you a competitive edge; in fact, the reduced losses mean you can label your BESS products as higher capacity (1.03 MWh rather than 1 MWh, for example) due to efficiency gains during battery discharge.

Small but mighty: increased energy density

Another advantage of SiC MOSFET PCS designs is that they are smaller than their silicon counterparts. In fact, you can reduce the size of your PCS by 60%. This means you can increase BESS energy density because you can use the saved space for additional battery capacity. You can also reduce integration costs because you need less panel space and fewer materials, and you can reduce transportation costs because your BESS assets are smaller and lighter.

Again, independent research backs this up: In the study I mentioned above, the researchers found that it was possible to reduce system weight by 61% because the LCL grid filter could be smaller (corresponding to a filter block size reduction of 64%). On another research project, Antxon Arrizabalaga and colleagues similarly found that it was possible to reduce filter volume by 80%.

In many BESS applications, size is important. With a SiC PCS, you can offer high performance from a small footprint and help your customers reach their targets in size-sensitive applications.

Higher power quality and optimised cooling

I’ve got two more key benefits to share with you:

First, SiC MOSFETs improve power quality. With some PCS solutions, you can achieve negligible DC ripple, and you can get THD values below 3% – with no additional filters. This helps you preserve the battery whilst also protecting connected inductive AC components such as transformers, and it therefore improves the overall reliability of your system. And by choosing a solution with no additional filters and isolating transformers, for example the DEIF iE Convert range, you can reduce system cost and complexity.

Second, the reduced heat losses that I discussed above reduce the need for cooling. This reduces system complexity and cost, and it helps you manage noise levels since cooling is a significant contributor to BESS noise. Some power converters like the DEIF iE Convert range offer liquid cooling which lets you locate the cooling system independently of the PCS and select the cooling method you prefer to optimise noise performance. (The high switching frequencies of SiC also contributes to lower noise; the human ear is unable to hear switching at 24 to 75kHz. By comparison, silicon IGBT components switch at audible frequencies between 1 and 5kHz.) In short, SiC lets you build solutions your customers can use when noise is unacceptable, for example, rental power in residential areas.