Solar Roof Info for 2023 Prius Prime

Its not a hybrid or EV, just a 2011 Dodge Gran Caravan minivan that I turned into a camper. The solar panel feeds a 280 Amp/h LifePo4 battery bank that I built. That's the equivalent of about 6 larger lead acid starter batteries.

This panel charges the battery bank enough to run a compressor fridge nonstop, being able to cook meals on a 1600 watt induction cooktop, run the water pump, run a TV, computer, use the Victron 120 volt inverter, gaming system, sound bar, fans, passive AC, LED interior lights, coffee maker, blender, you name it. It runs everything for 3 days, in case it gets cloudy.

The battery bank can also be charged with a 120 volt external hookup or with a 12v charger for the alternator.

Eventually I will buy a new Sienna, install a 600 watt panel on the roof, and tap into the existing traction battery. This will allow me to install and run a dedicated AC through the night without the ICE coming on.

I do all the work myself. Not sure about the daily watt-hours. I have to look into the BMS or Victron charger apps. They all have bloototth dongles. The system usually fully recharges after 2 to 3 hours of sunlight and goes into a trickle charge right after.

MPG is down by about 1 on the highway at 70. I was expecting a higher loss. I can't hear any change in wind noise from the panel, no droning either.

Its a commercial grade full size panel that goes onto roofs, so there is no issue with heat. It offers shade on the car, hence the interior temps are lower when the car is parked.

The panel weights about 40 pounds, the LifePo4 battery bank maybe 60 pounds. The roof rail is 6063 Aluminum U-Channel at about 5 pounds. The chargers and cables another 15 or so.

For a traction battery, and in order to get some mileage out of it, a 465 or even 600 watt panel would only be a trickle charge and not worth the effort.


I installed the battery bank, chargers, etc into floor of the minivan.




Building / balancing / compressing the battery bank:




Just enough room for my pet and myself.




We love going on long weekend trips.







Its a nice stealth camper. Allows us to stay over night in the best spots without having to pay an RV park.

 

Impressive set of instruments.

 

Where are you coming up with 20% lower efficiency for the 19 inch tires on the 2023 Prius prime? Toyota's web site for the 2023 Prius (non prime) shows slightly higher MPG using 17 inch tires on a 2023 Prius HEV, but it's also a different car. Is it normal in the BEV world for the range to take 20% efficiency hit just because of a change of tire size? That just seems like bad engineering.

While we are at it, could someone explain the difference between having efficient LRR tires that reduce gas consumption while driving as compared to having a solar roof that charges the traction battery all day long (in the Prime), even when it's not moving? My take on it is that in the first case, you burn less gas, but only while moving. In the second case, you may have less range due to increased rolling resistance As long as you don't deplete the battery you can still use no gas for a longer period of time, and (theoretically) don't need to burn more hydrocarbons in order to complete your drive.

 

Thanks for sharing that.

I have a friend who is making similar 'stealth camper' installations. He's shown me some really innovative layouts based on the new tall vans. If I were ever to hit the road, that would be the life style that I'd like to explore.

 

Gen 5 Prius PHEV (Prius Prime) specs have been published in Japan and the 17" tires result in 22% higher fuel economy and EV range.

Yes, if you park your car under sun, you can get about 2 kWh a day if you park it all day long, but the Toyota Japan website specifically instructs not to park the solar-roof-equipped models under the sun, as they say that would damage the solar cells.

 

It turns out that the solar roof only provides power to the 12-V system when the car is on. It only charges the PHEV battery when the car is off—it does not charge the PHEV battery or provide power to the motor–generators when the car is on.

This makes the solar roof almost useless to me because I always avoid parking the car under the sun to protect the paint from fading and the interior materials from being deteriorated.

I looked at the US manual, and this is what it says. It says, "Do not condense sunlight," which could mean do not focus light with a lens or mirror—I don't know. However, it looks like the solar cells may be turning off if the sun is too intense due to "the temperature-preservation function."

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• Do not condense sunlight onto the solar roof

●In the following cases, the solar charging system stops solar power generation and power supply to the hybrid battery (traction battery) and auxiliary systems.
• The temperature preservation function of the solar charging system operates

...

●When the vehicle is left in the hot weather, the temperature preservation function of the solar charging system becomes easy to operate due to high temperature of the vehicle interior.

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Moreover, the solar roof does not seem to charge the 12-V battery when the car is off.

 

what kind of solar panel isn't designed to be in the sun?

 

It looks like because it is installed on a car, the inside of the panel can get too hot since it does not ventilate from the bottom when the inside of the car gets hot under the sun. That is probably why they put a "temperature-preservation function" to stop the solar cells from generating power above a certain temperature.

 

wow, that could make parking really difficult for many

 

This may mean less than you think it does, though, because without the solar roof, it's the PHEV battery and motor-generators that have to provide that power to the 12 volt system. That's generally nearly half a kilowatt of base load, more if you've got the larger loads operating, defoggers, seat heaters, etc.

The max capacity of the solar roof isn't any more than that, right? So any amount of that base load that the roof is holding up does not have to come out of the PHEV battery or the MGs. Electrons are fungible.

 

You still need to park it under the sun. The owner's manual says:

●If even part of the solar roof is in the shade, there may be an extreme drop in power generation.

 

yeah, i think i'm confused

 

Perhaps keeping the windows cracked open prevents the temperature-preservation function from kicking in.

In summary, you get about 1–2 kWh of charge if you park your car in the sun for all day, good for 5–10 miles of city driving.

 

This is how the solar roof worked in the gen4 Prime.

 

500 W, which is about 40 A, does not sound right for the typical operating power drain of a 12-V car battery system. The fusible link on the Prius Prime battery is probably not much more than 40 A if not less. Halogen headlamps used to drain about 110 W, which made the majority of the power drain. These days, if the lights and heaters etc. are off, you are probably looking at no more than about 50 W.

The fact that the Prius Prime uses the very small BCI 140R/EN LN1/DIN H4 battery group size also indicates that there is not much 12-V-power requirement.

 

I was going by the typical base 12 volt load in READY that people have consistently measured in earlier Prius generations. If the Prime has managed to cut that by a factor of ten, that's fabulous, but I don't know if it has.

What makes you think the fusible link on the Prius Prime battery would be "not much more than 40 A if not less"? I mean, without even looking it up for the Prime, it being 120 amps in Gen 1 and Gen 2 and 140 amps in Gen 3 would make a person wonder about it suddenly getting that small in the Prime.

The base load increases if you add heavy power users like the defoggers, seat heaters, etc. The steering assist motor can draw heavy current when you turn corners at low speeds. In the non-Prime, there's an electric supplemental heat element that's around 700 watts all by itself.

The DC/DC converter in Gen 3 has a published output rating of 120 amps, or around a kilowatt and a half. People sometimes accessorize their Prii with things that draw up to a kilowatt, which is sustainable if the car is READY and only the base car load is being drawn. But, naturally, Toyota didn't go specifying a needlessly-oversized converter; there are times when the stuff in the car can add up pretty close to its capacity.

 

500 W would roughly be 15% of the total power in city driving (about 3.3 kW averaged over a city trip). Typical conservatively set A/C load in eco mode is less than that. On the Prius Prime, A/C is directly powered by the PHEV battery through a dedicated inverter; so, the solar roof cannot run the A/C:

(c) An air conditioning inverter is integrated with the compressor with motor assembly. This inverter operates the compressor on HV battery voltage. As a result, the air conditioning system is actuated without depending on the operation of the engine, thus realizing a comfortable air conditioning system and low fuel consumption.

So, the full 214 W from the solar roof would only be 6% of the total power consumption in city driving, far too little to make up the 22% extra power needed by the 19" tires. I originally wanted the XSE Premium with the solar roof, thinking that all trims had the same fuel efficiency and BEV range, but after seeing the actual published specs, the SE with the 17" tires seem to be win–win in all respects.

 

That's not just Prius Prime, by the way; that's every Prius starting with Gen 2. (In Gen 2, the A/C inverter was in the inverter box above the transaxle; Gen 3 was when that circuit moved into the compressor itself.)

 

That seems disappeared in the gen 5.