BrokerDon
Active Member
Until your solar panel gets stolen like all the catalytic converters.
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Solar Panel on Model S - time to reconsider?
- Thread starter Sir Guacamolaf
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- Model S
BrokerDon
Active Member
We installed a 41" x 61" 327W SunPower solar panel and 40A Renogy Tracer MPPT charge controller (converts 63V DC to 12.5V DC maintenance to 13.8V DC boost) on the roof of our Winnebago View 8 years ago. It generates enough power to run our RV's LED lights, ceiling fans, Verizon JetPack MiFi hotspot, Panasonic SmartCam+ security camera, 12V DC 32" TV, and run our MacBook Pro laptops. However our 327W solar panel definitely won't provide enough power for our 13.5k BTU AC, microwave, hair dryer, etc. and cost $400 for the 327W panel, charge controller and wiring. The same applies to a car. Solar panels Wattage output on vehicles suffer from being mounted FLAT on the vehicle roofs unlike structure mounted panels which are mounted at specific angles towards the sun based on their permanent location... and they generate a LOT of heat requiring mounting above the roof for maximum performance (
solar panel temperature =
power output).
We also have a 2012 Toyota Prius Four which has an integrated solar panel in it's roof... but it only generates enough power to run the blower to bring in outside air into the car on sunny days so it doesn't become an over with the windows closed. Works well but obviously doesn't product enough power to do anything other than power the blower fan. No battery recharge.
Bottom line: If adding solar panels to EVs made actual energy (not marketing) sense, Tesla and every EV maker would do it. Clearly it doesn't now. Maybe some day it will.
solar panel temperature = power output).We also have a 2012 Toyota Prius Four which has an integrated solar panel in it's roof... but it only generates enough power to run the blower to bring in outside air into the car on sunny days so it doesn't become an over with the windows closed. Works well but obviously doesn't product enough power to do anything other than power the blower fan. No battery recharge.
Bottom line: If adding solar panels to EVs made actual energy (not marketing) sense, Tesla and every EV maker would do it. Clearly it doesn't now. Maybe some day it will.
The thing is- it won't. Current solar panels are already about 25% efficient. If you could get to 100% efficiency, you will only get 4X the power, and physics says 100% efficiency is impossible.
Maybe we'll get to 2X current power. That doesn't really help much given the baseline is more like 1 mile a day, not 100.
BrokerDon
Active Member
Another explanation why solar panels aren't good answer for EV charging:
apple.news
Think The Solar Canopy Is Powering EV Fast Chargers? Think Again. — VICE
Fast chargers require so much electricity it would take many more solar panels to power one of them.
apple.news
n2mb_racing
Active Member
Also interesting to note that you'd have to re-design the vehicle architecture and add another charger to do solar charging. Just waking up the car to start charging consumes ~300W, so you'd lose more power than you put in. But, it wouldn't be a bad idea to add a small panel to keep the 12V battery topped up and deal with all the other phantom power loads. Might be enough to power the computers for sentry mode, etc.
It won't.
Sentry mode is 10's of watts to keep the computers and cameras running. Let's say it's really well designed (it's not currently) and is only 40W. That's 960Wh per day.
If parked outside all day with no shade in a good area, that would require a 200W panel- which is 20% of a square meter. About two square feet. That's huge area to reserve on a car.
If you care about the environment, it's really not very smart to use sentry mode. A Model 3 draws about 200-300W when the HV circuit is on, and Sentry mode requires this. That's 5kWh per day. The same as driving 24 miles per day or 8,700miles a year all just so you can record possible damage to your car. If the average car drives 12,000 miles a year, this is like increasing your driving by 70%, and the best thing we can all do is reduce total energy use, not just physical miles driven.
This means a solar cell to support Sentry mode needs to do 5kWh a day, which would be about 6.5 square meters (if you always park outside in the sun). The whole area of a model 3 is 8.7 meters.
Finally- a Tesla "tops up" the 12V battery every few hours as it is. Solar's not very useful when it's only functional a few hours a day- you literally would want a larger, more expensive 12V battery to handle the much deeper discharge cycles a solar 24h cycle requires.
n2mb_racing
Active Member
Well, but Sentry mode is mostly used when parked outside somewhere, likely during the day. I don't have it active at home when parked in my garage.
Ideally, Tesla could optimize Sentry some more. It should only consume a few watts, but the software / hardware aren't efficient.
But, yeah, not willing to sacrifice having video of vandalism or theft to reduce energy usage. It's worth it for the insurance. I made a claim for damage to my bumper from someone backing into my car in a parking lot on my old Model S before sentry, and the insurance company didn't believe me because I didn't have proof. They treated it as an accident and raised my rates.
Yes, in completely different hardware, maybe. However, nobody in the world currently knows how to run 5+ automotive, HDR, 2K cameras and then do CV processing on them in real time to detect people and estimate distance and write that video to disk in under 10W. Hence my 40W estimate from before (which would still be beyond world class right now, just the CV is probably 20W)
By $200+ a year, the cost of running Sentry year round?
As an FYI, if you care about insurance rates and long term costs, the correct thing to do is raise your deducible to $1K-$2K and not file for anything under about $4K. I would never file with insurance for a $1K-$2K bumper issue, of course that is going to raise your rates and cost you over the long term.
The real issue here is that you pay for the solar panel, and the conversion electronics, which make the car more expensive and heavier. Society benefits much more from putting solar in fixed locations than on cars, which as you say, are often parked in garages making them worthless. We should be using any solar we can produce to reduce overall carbon generating energy production, not slapping them on luxury cars to produce 1/10th the energy they could somewhere else so we can run Sentry mode without guilt (as long as we don't think about it toooo hard)
Plus, why would you pay $500 for a solar panel on your car that will save you $100 in electricity over the life of the car?
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Electric700
Active Member
I think integrated solar panels should be an option. For some it can be a benefit since it can help the vehicle gain range while parked if the car is usually outside, and when parked almost always has an unobstructed path to the sky. For others, it just doesn't make sense if the vehicle will spend a lot of time parked in garages.
Solar panels can last 25+ years. There are still some cars out on the road today that are older than that! Hopefully as the technology improves, the solar panel longevity can as well.
Solar panels can last 25+ years. There are still some cars out on the road today that are older than that! Hopefully as the technology improves, the solar panel longevity can as well.
You really need to read the thread. A solar panel that literally covers the whole roof of a Model S (no more glass roof) will gain you a range of less than 5 miles a day when parked in an optimal place. When combined with vampire draw and realistic conversion losses it's more like 3 miles or less. It's not actually clear a Tesla today knows how to charge itself without 300W of overhead, which actually means a net zero gain in a day with a 1.5 sq meter panel.
This is exactly why putting them on cars is dumb. If you put them on the ground in a great place, they create optimal energy for 25 years. Put them on a car, and the average car life is 12 years- getting less than 1/2 of the life of the panel before it's trashed, and also getting way less than optimal capture from them over that time.
redmunds
Member
The car will have the same drain with or without solar panels, so that is not relevant.
No it won't. The car draws much more power when the HV circuit is active, which is required for charging (or to use sentry mode...). Right now this is near 300W, so the first 300W of charging goes purely into heat. And before you go "well, they could do better there".... Yes, we should all be asking Tesla to reduce vampire drain, not putting on solar panels.
A 1.5 square meter solar panel can do 1.5kWh on a great day. So let's say across the fleet, in all locations, across vehicles parked outside and in garages, across weather, we get 1/3 of that. 500Wh per car.
That's <2 miles of vampire drain per day. 20watts continuous draw. If Tesla did work in software and future HW to remove just 20w of draw, they would have saved more energy than they ever could with solar panels. This has a double benefit too, because this is actually energy not used, not just energy collected and wasted, and then we can use those unused solar square meters to do generation for other uses.
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