Bidirectional converter tech explained: The secrets behind Hoymiles Micro Storage (MS)

Hoymiles Micro Storage (MS) is changing the game in balcony solar energy storage and the micro storage settings at large. As the first AC-coupled solution of its kind, it offers a compelling alternative to traditional DC-coupled systems. In our previous blog, we introduced the unmatched flexibility and simplicity of Hoymiles’ AC-coupled solution. The driving force behind this innovation is the bidirectional converter technology, which unlocks a new level of energy management for balcony solar users. Let’s take a closer look at Hoymiles MS and how it’s transforming balcony solar energy systems and other micro solar systems.

What is bidirectional converter technology?

Bidirectional converter technology, as the name suggests, converts power between DC and AC in both directions. Microinverters leverage this technology to do two things:
  • Convert the DC power produced by PV modules into AC power required by most household appliances and consumer electronics
  • Convert AC power (from microinverter and the grid) into DC power for battery storage
Does that concept sound familiar? That’s because that’s how hybrid PV systems operate, enabling users to import power from the grid or save excess solar power and store it in batteries as DC power. But here’s the key difference: While this technology is widely employed in larger residential energy storage systems, it’s rarely seen in micro installations such as balcony solar systems. Hoymiles MS is bucking that trend. Unlike typical micro-scale solar power systems that only convert power from DC to AC, Hoymiles MS can also draw AC power from the grid during off-peak hours and convert it to DC for battery charging. This represents a massive step towards energy independence.

The Hoymiles MS advantage

To fully appreciate the benefits of Hoymiles MS, it’s key to understand the challenges faced by balcony solar power systems that use a regular DC-coupled microinverter and a battery.

In a typical DC-coupled energy storage system, the wiring follows this sequence: PV modules > energy storage/battery > microinverter > socket/grid.

The Hoymiles MS advantage

In this setup, the energy storage unit can only convert power in one direction – from DC to AC.

This is how it works: The energy storage unit is connected directly to the PV modules. As it charges up with DC solar energy, it passes that energy along to the microinverter, which converts the DC energy to AC.

That energy can then be used safely in all of the property’s outlets. Any energy that the property doesn’t use remains in the energy storage unit, waiting until it’s needed.

But this configuration creates performance and compatibility issues. Here’s why:

  • Microinverters are designed to connect directly to solar panels and continuously monitor the amount of DC power being generated, so they can optimize maximum power point tracking (MPPT). However, when you place an energy storage unit between the panel and the microinverter, the microinverter receives DC power from the storage unit instead of directly from the panel.
  • This means the energy storage unit must try and copy the output characteristics of the solar panel to match the microinverter’s MPPT algorithm – in other words, it has to “pretend” that the DC power it transmits is the DC power generated by the PV modules.
  • Every microinverter brand has a different MPPT algorithm, which can make it even harder for the energy storage unit to work smoothly with the microinverter. As a result, users often experience suboptimal performance and compatibility issues between the energy storage unit and the microinverter.

There is another drawback: This type of solar system can’t combine grid power with solar power. The microinverter is connected to the grid, but it can’t convert the grid’s AC power back into DC power, which means that grid power can’t be stored in the battery for later.

If the microinverter could convert AC to DC, the solar system could use grid power to charge the battery – providing an extra source of reliable backup power on cloudy days when solar systems generate less energy.

But most balcony solar systems don’t have this capability – which is a major drawback for those seeking true energy independence and reliable backup power.

How Hoymiles MS addresses these challenges

Hoymiles is tackling these challenges head-on with our advanced AC-coupled design, made possible by bidirectional converter technology.

In the Hoymiles MS system, the energy storage unit isn’t connected directly to the PV modules.

Instead, it has the following configuration: PV modules > microinverter > energy storage/battery > grid.

Hoymiles MS system, the energy storage system

A micro energy storage unit sits between the microinverter and the grid. This means the microinverter can convert power directly from the PV modules, with no need for MPPT algorithm emulation. That makes the Hoymiles MS system compatible with 100% of microinverters.

Crucially, moving the energy storage unit means it can be charged by two different power sources: the PV panel (via the microinverter) and the grid.

Hoymiles MS Micro Storage Shines in Munich! 9

Portable power supply (PPS) for flexibility and convenience

Hoymiles MS further distinguishes itself from the competition by offering an off-grid mode, providing an additional layer of energy security and independence.

The built-in 2.24 kWh kWh battery offers a dependable emergency backup power source, which is particularly useful in areas with unreliable grid power. If the grid goes down, you can easily connect to the off-grid port, ensuring that your critical appliances and devices remain operational.

But Hoymiles MS’s versatility doesn’t stop there. It also functions as a portable power supply, perfect for outdoor activities, such as camping trips, outdoor events, or any other time you need power on the go.

Seamless installation in seconds

Hoymiles MS boasts an incredibly simple installation process, which takes a mere seven seconds!

To install Hoymiles MS, simply unplug the microinverter and connect Hoymiles MS between the microinverter and the power source. It’s that straightforward.

Its plug-and-play design makes it accessible to users with any level of technical expertise, eliminating the need for complicated wiring or time-consuming setups.

With Hoymiles MS, you can access cutting-edge solar storage, free from complex installations and compatibility headaches

Hoymiles MS boasts an incredibly simple installation process