German start-up Sax Power GmbH is offering a residential AC battery it says works entirely without an inverter and has 50% more capacity and service life than conventional batteries.
According to its specifications, the battery stores direct current and can deliver both alternating current and direct current. The conversion is not carried out by transistors such as IGBTs or MOSFETs, but via the software of the battery management system.
By interconnecting with cascaded H-bridges, the cell blocks can be controlled individually. That enables the system to build a sinusoidal curve typical of alternating current from the individual DC voltage values. It also increases efficiency, since the conversion is purely electronic. Sax states the efficiency of its solution is 99%. The option of plugging the battery into a main socket is a further innovation, according to the company.
Sax Power said that in this type of device the current is measured by folding current transformers. That means no cables have to be disconnected in a household network. In addition, a second current measurement of the same type is carried out on the feeding line to the house. The battery then receives the information it needs for optimal use, via wireless communication units.
The manufacturer said some performance can be lost with the plug-in device, which has a nominal power output of 3.7 kW. The standard product, without the plug-in, has an output of 4.6 kW.
The battery comes with lithium iron phosphate cells and the capacity of the basic model is 5.2 kWh but it can be expanded with extra modules to 15.6 kWh. The nominal current is 20 A, or 16 A with the plug-in installation.
The company offers a 10-year guarantee for the device, which weighs 52kg and is said to be easier for installers to mount as they do not have to handle an inverter.
In May, the product received a German Innovation Award and Sax Power said it will be on display in October at the EES storage fair held alongside The Smarter E trade event. The developer said its product has qualified as a finalist for the EES Award at this year’s show.
A price for the product can be found on the Sax Power website. The basic version is listed as costing €5,079 ($5,976). In a version with wireless communication and a better smart meter, the device costs €5,210 ($6,130). It will be sold in series beginning this autumn.
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Few technology stories fit under the headline “Game Changer”… but this one just might.
I Hope that these can reach the price point so that every home and business has one in the near future.
Definitely looking forward to more information on this!
They have a website https://sax-power.net/ that can be switched to an English version. However, the battery for photovoltaics is only available in Germany so far. US and other markets are planned, but that needs adaptions on the technical side (different voltage in the American grid) and separate certifications. The PV market is only their starting point, the really interesting part will be application of that principle to e-cars.
We’ll take it!
“The conversion is not carried out by transistors such as IGBTs or MOSFETs, but via the software of the battery management system. By interconnecting with cascaded H-bridges, the cell blocks can be controlled individually.”
“H-Bridges” are a circuit design. They are often made out of MOSFETs. There is definitely an inverter in there.
https://en.m.wikipedia.org/wiki/H-bridge
See the section under “Operation as an inverter”: “A common use of the H-bridge is an inverter.”
I believe that they are trying to say that you do not need a SEPARATE inverter.
@Kris B:
The SAX technology works differentlly. They use H-bridges not to build an inverter but to connect to blocks of battery cells that can then be managed individually. The BMS works with the DC voltage values of these blocks and combines them in a way that delivers the required output – e.g. building a sinus curve to get AC. It’s an invertion by software, not by hardware, so what you see in the battery case is just the cells and the circuits that connect to them. The efficiency of 99% is also higher than what any “hardware inverter” can deliver (96 to 98%).
@René Granacher
Actually SolarEdge HDWave inverters are greater than 99% efficient so it is not greater than what any “hardware inverter” can deliver.