Possible to buy a Prime with the Solar Charging Roof?

I think you'd have to get pretty far into the technical weeds to find the true answer, but it seems to go against common sense to have the solar roof charging the 12V battery, and not use it as a selling point. Someone who has done a deep dive into the technical manuals may reveal the answer some day.

 

The 12-V system, which is either powered by the 12-V battery or the DC–DC converter or a sub DC–DC converter must be on during any kind of traction-battery charging. That is because the 12-V system is what runs the computers, including the charging computers. Without the 12-V system being active, the car is at deep sleep, doing virtually nothing.

There is a sub DC–DC converter in the Gen 4 AC charger, which generates about 12.89 V during AC charging, which powers the 12-V system and prevents the 12-V battery from draining but does not charge it during traction battery charging. Without that, you would have a dead 12-V battery often when you charged the traction battery. Note that the main DC–DC converter in Gen 4 does not turn on during traction-battery charging.

I am guessing that there is a sub DC–DC converter in the Gen 5 solar charger, and the operation is identical to Gen 4 AC charging, which I described in detail in the paragraph above.

In the Gen 5 AC charger, there is no sub DC–DC converter; so, the main DC–DC converter is turned on during traction-battery charging. It is not only that but the voltage of the main DC–DC converter is kept at 14.1 V, which charges the 12-V battery. Note that the voltage of the main DC–DC converter is normally kept at 12.89 V over 90% of the time when you drive the car, which only keeps the 12-V battery from discharging but does not charge it.

If this is still not clear, I give up. LOL

 

I've never heard of a solar panel charge controller that needed an external power source. I'm sure the circuitry incorporates some sort of buck converter to draw power for the circuitry from the panel. Drawing power from the 12V system seem very unlikely.

 

I didn't know about a 'sub DC-DC converter'; but the documents I've read stated that 12V was provided to ensure traction battery cooling fan operations during charging - so the traction pack doesn't over-heat while charging. The logic circuits itself, doesn't draw enough power to require 12V DC-DC converter to be turned ON was my point. There's a "boat anchor size battery" for that. If the aux. battery was below 12.89VDC; then technically, it would be receiving a charge; all be it a very minuscule one.
Remind me how big and heavy your cell phone battery is and how it's able to function for at least a day without recharging.

No offense.....

 

Yes, there is a sub DC–DC converter in the Gen 4 AC charger. That is why I believe there is a sub DC–DC converter in the Gen 5 solar charger. Without that, you would rapidly deplete the 12-V battery during solar charging running the car computers, the cooling fan as you mentioned, etc.

At the 12.89–13.05 V output of the sub DC–DC converter (or the main DC–DC converter when the system does constant voltage control to reduce energy consumption (power = voltage times current) while driving, which is over 90% of the time), the 12-V battery will receive some charge, yes, but it will be minimal. It is called a float voltage, which is a very common term. You need about 14.0 V or higher to efficiently charge a 12-V battery. Even at 13.53 V, which is the voltage output of the main DC–DC converter at the park gear position, you hardly put any charge in the 12-V battery.

The idle electric power requirement of Prius is incredibly high. Even when only some systems are turned on, you would need a sub DC–DC converter to prevent the 12-V battery from rapidly discharging.

 

The smartphone lithium-ion battery is about 5 Ah and can take a full discharge daily. You cannot repeatedly drain and charge a lead–acid battery more than about 10% SOC without damaging it. So, effectively, you don’t get much more charge capacity for the Prius battery than for your smartphone battery. Not to mention that the systems in the Prius will consume more power than in the smartphone, as they are not particularly designed for low-power consumption.

 

I recall seeing the solar 12V wiring while looking into the other sub DC-DC converter's absence here.

WeberAuto: 2024 Prius Prime PHEV Low-Voltage Charging System Testing | Page 2 | PriusChat

The solar charger has an "AMD"-named 12V connection, which seems to be the unidentified acronym for output-capable connections. And that connection has a fairly generous 40A fuse on it. I don't know if that's high enough to suggest it could be capable of actually charging.

For comparison the main DC/DC converter has 130A.
The G4 charger sub DC/DC converter had 30A.
(The G5 charger without the DC/DC converter has 10A.)

 

I went to cars.com three weeks ago. Found one coming to a Milwaukee dealer on the exact color I wanted. Put money down. Drove it home last weekend. Now I have exactly what I wanted (with the solar charging roof). Very pleased!

 

Would you be able to install a BM2 battery monitor so that we find out how the 12-V system behaves with a solar roof?

BM2 battery monitor on Amazon