This is true, however, as someone on this forum pointed out:
The losses come mostly from the switching from a smooth DC to a pulsed signal. Whether it inverts it to AC is only part of the process.
If I can be a bit pedantic, there is no pulsing of the DC "signal". The current is switched between two different routes. In a buck converter the output current is switched between the input or through ground. In a boost converter the input current is switched between ground and the output. It's hard to describe the voltages, but the important one, the output, is relatively constant in both configurations.
I guess my point is there is no benefit from desribing what is happening in a DC/DC converter as any sort of AC signal.
Ideally a solar to DC battery charger would take the DC from a PV panels and convert it to DC at the correct voltage to provide the current that the battery wants for charging.
Having an MPPT convert a PV's DC into AC at optimal power, then having an AC-DC battery charger convert it back to the right DC current and voltage for optimal for battery charging really isn't much more lossy than DC to DC conversion. Essentially the same switching has to be done.
There's the sticky wicket. An MPPT is going to control the IV (current/voltage) operating point of the PV panel to obtain maximum power. But then where does that power go? I don't know the details of EV charging, but I am aware that in level 2 charging the EVSE only indicates the maximum current available and the Battery Management System (BMS) draws as much as it wants up to the EVSE indicated maximum. So if the MPPT adjusts the operating point of the PV to produce more power (and therefore current) and the car does not use it, where does the power go? I expect it will be necessary to have a battery or a very large capacitor in the EVSE to buffer the fluctuations in PV supplied power to match the BMS drawn power.
This is something I'm sure has been worked out, I just don't know how they do it.
Converting to AC is pointless and is less efficient than direct DC/DC conversion. It's actually hard to produce a sinewave AC power output. Often a modified sinewave is used. But if it is not useful (which in this case it is not) it absolutely is less efficient than direct DC/DC conversion.
While their website does a very poor job at describing it:
From more careful looks at today's website and from their previous Ossiaco website and emails I exchanged with their principals in the past; It is a bi-directional CHAdeMO EV charger, an household AC inverter, a J-1772 EVSE, an AC transfer switch, and a PhotoVoltaic MPPT controller, all in one box. Note that they lament that the Tesla CHAdeMO adapter does not support bi-directional use. They aren't available and haven't ever sold anything so, for now, they are vaporware.
AC transfer switch? So they are combining this with a connection to the AC line, but I guess that's just a mechanical switch and no power is supplied to the AC line. That's why they are producing AC, so it can work off the PV panel
OR the AC line using a simple swtich and all other components off the shelf. If this were designed at the board level they could use a simple DC/DC converter and add an AC input, so either AC or DC to DC. That is much more simple than the arrangement they are using.
I wonder how they get the PV power matched to the power input to the EV?
Its not exactly:
but, if they ever produce it, it would be more of a high power PV system that can fully charge your car and power your home, either from the PV or from your car's battery. I thought about hanging onto my Leaf for use as a rolling Powerwall equivalent if they ever come out with the product.
I have no interest in powering anything from my EV other than the EV. The most expensive part of the car is the battery and I want to preserve it as much as possible. I'm not going to use an expensive car to replace a $500 generator.
I would like to explore wind power which is claimed to be cheaper than PV solar. But that's at the commercial level and a small windmill seems very pricey for what you get.