Solar roof option?

Solar roof option?

Im currently reading David Mackay's "Sustainable Energy" ( very interesting read by the way) so i'm curious why Tesla isn't incorporating a few solar panels on the roof of Model S to help offset the energy drain from running AC in hot climates. Could this be an option? Perhaps something appealing to aftermarket suppliers? Probably a bit complex to install after the build. Better if Tesla offered it OEM. Looking forward to getting this auto, kudos to Tesla for having the brains and funding to see this project through!

Tech26 | October 9, 2011

Likely to show up as an option. Base model probably wont have it. The solar roof is a great idea but still pricey and barely generates enough energy to keep the interior cool for you while you're away.

Volker.Berlin | October 10, 2011

This question keeps popping up in these forums. Here are some threads that may be worth reading:

To summarize: The opinion here in the Tesla forum is that solar panels (as can be found on the Fisker Karma) are merely for coolness and (pseudo) green image. The amount of electricity generated by a photo voltaic area as small as the roof and/or bonnet of a passenger car is so small, that a) it is not really good for anything except maybe running an additional fan while the car is sitting in the sun, and b) if you want to run an additional fan you could as well draw the power from the main battery which would not be affected much. Photo voltaic cells need to be produced, integrated into the car's electricity, and maintained -- at the current state of technology, it does not seem worth the cost and trouble.

Schlermie | October 10, 2011

One of the Tesla staff commented that turning on all auxiliary systems (A/C, headlights, etc.) adds another 5% tax on the battery. No details on how he arrived at that number though.

Brian H | October 10, 2011

The solar roof stories will stop as soon as we run out of arithmetic-challenged humans.

In other words, never.

Timo | October 10, 2011

Never say never. It will happen eventually. Problem though is that at the same time we probably run out of also arithmetic-skilled people. Robots take over the world. (I got severe "terminator" vibes from US military latest unmanned armed robotic planes that work together and choose independently without human interaction whether or not shoot the target. Only thing that was missing was "Skynet" as controlling entity. Or not.)

Ramon123 | November 6, 2011

I've been researching stats, pricing for my solar array for my house and the panel prices have dropped a LOT over the past 18 months.
Currently, no problem finding a 5X3 foot panel rated at 240 watts
for between $360 and $500 (and others higher, depending on brand and retailer). No need for inverter as it would feed the Tesla's battery directly - would need to alter voltage, however. I suppose one might manage to install enough cells on the Tesla roof to produce 450 watts peak power. Peak solar harvest in summer, lower latitudes would be 7 sun hours or so (7X450= 3.1 kilowatthours, or around 12 miles of range). At higher latitudes, yearly average, figure around 1.6 kilowatthours, or 6 miles of driving range per full day of sun). About 18 cents worth of electricity. For a vehicle with a battery capacity pushing 90 kilowatt hours, of very slight benefit, unless the roof can be built with optional cost less that $300 of so (would pay for itself in about 4 to 5 years, assuming cost of electricity at national average). At $600 optional cost, of rather marginal benefit, at $1000 optional cost, forget it.

EdG | November 6, 2011

@Ramon123: Unless you're always going to be home when it's sunny, you're going to have to store the solar power somewhere (unless you do as I do and push it to the neighbors with an inverter). I guess you'd have to have a battery system that charges to the desired voltage and then bleeds off to the S when you get home. Adds to the cost and complexity.

CIAOPEC | November 14, 2011

Just to be clear. I have no expectation that a modest solar panel would charge the car significantly.That's fanasyland given the current efficiency of photovoltaics. I just think ( when the sun is shining & the the A/C is running at its peak) supplementing the power drain makes sense. Chances are when you are asking for A/C the sun is likely to be shinning...At the very least a modest sized solar panel is more than enough to run a fan to keep the cabin air circulating when the vehicle is parked. Just by keeping the cabin temp from rising significantly over outside temp it would save a significant power drain to subsequently cool the cabin down when the driver returned. This would basically operate like a heat pump in reverse. Perhaps this effect would even prevent or reduce the chance of death if a child or pet was accidentally left in the car?

On the other hand why haven't automobile manufacturers come up with a simple cabin CO2 sensor that could easily detect a person or animal left in a car? Seems pretty basic to me. Hard to believe this hasn't been worked out... Detect an elevated level of CO2 and the car automatically sends out an alert to the driver and/or lowers the windows or activates A/C to cool the interior to a safe level.

jbunn | November 14, 2011


Powering the neighbors is the right thing to do. Batteries for a home solar are not cost effective. Collect sun in the daytime when the Tesla is at work and spin the meter backwards. In the evening, spin in the other direction. The grid becomes your battery.

In Washington state you can sell power back for 4 to 5 times the purchase rate using Washington State manufactured panels and inverters. You can spin the meter backwards pretty darn fast.

Mycroft | November 15, 2011

Would you pay $5,000 for an optional solar roof that's just powerful enough to run a frickin fan? Plus you lose the pano roof.

CIAOPEC | November 15, 2011

No need to cover the entire roof with a solar panel to power a recirculating fan. I'm also looking forward to my pano roof, I just don't see these two elements being mutually exclusive. If so I would choose the pano.

Those familiar with the boating or sailing world are well aware of small solar power deck vents (some work better than others). The solar elements are tiny.

you can see an example here:

I'm not endorsing this brand per se or suggesting slapping this on a car (ugly and would destroy the model S 0.22cd), just using this as a proof of concept. Don't freak out! No need to F bomb...

These tiny solar units can move 1000cu.ft/hour and are relatively cheap, usually around $200. As an option on a car, say $300-500 i would consider it.

Nicu | November 15, 2011

This has been extensively discussed here. There is no point in spending extra (both to design, test, install and maintain) when the battery is huge comparatively and the effect on range is insignificant. It's like adding bicycle pedals for the passenger in an ICE vehicle. That could power a fan or have half a mile of extra range (if she works hard for a few hours) but really there is no point in doing so.

BYT | November 15, 2011

@Nicu, Can we add pedals that generate electricity to the jump seats? This keeps the kids in the back occupied and can probably generate 6kw per hour especially after Halloween!

Brian H | November 15, 2011

If you want car roof solar, buy a Karma. Then spend years wishing you'd bought an 'S'. >:)

Jumpseat pedal power! I like it... but you'd end up with kids with big, muscular legs. Could be some downside there. ;)

Brian H | November 15, 2011

Thinking further about the jumpseat pedal powering, putting ammeters in front of the kids so they could compete would probably work like a charm!

BYT | November 15, 2011

@Brian, LOL, my dad as a kid put ankle weights on me (15 lbs. on each leg) and made me go up and down the steps on the deck of our home for 30 minutes everyday. My legs were huge and although I hated doing it, I have a great set of stems (my favorite body part) and am glad he made me do it! The kids will thank you later... :D

Good luck trying to catch them however when they are naughty!

Brian H | November 16, 2011

And so, in later life, you went on to make your fame and fortune as a pro football place-kicker? |8-0

Brian H | November 16, 2011

6kw per hour is meaningless; kw is instantaneous power. 6kwh per hour would be energy (a very impressive amount, equivalent to what about 16 plow horses would produce!)
And "everyday" means usual, ordinary. To say "each day" separate the words, as in "every day".

Volker.Berlin | November 16, 2011

Brian H, methinks you should rethink the definition and meaning of kw(h). Just a hint.

Robert.Boston | November 16, 2011

The great thing about the jumpseat pedals would be the reactions of the drivers behind, seeing this amazing car going 70mph with just two kids pedaling....

Volker.Berlin | November 16, 2011

I recall my post regarding kw(h). My mistake, you are right. It is still annoying that you absolutely have to pick on each and every typo, regardless how irrelevant that is. But you know that, I told you already.

Timo | November 16, 2011

Volker.Berlin, I don't see anything wrong in Brian H text about kWh and kW. You can produce 6kWh in a hour just like you can produce 3kWh in half an hour. That then requires 6kW average power output for a hour to produce 6kWh. (energy produced / time to produce it = power).

If BYT had said "6kW for a hour" then that correction would have no ground, but since he said "6kW per hour" I agree with Brian H, that's wrong use of the unit.

Volker.Berlin | November 16, 2011

Oh yeah, and this fundamental mistake totally changes the meaning of BYT's post to almost the opposite. Or does it...? Man, you guys are more German than any German I know. (Americans usually refer to this particular trait with a term that I, as a German, do not use.)

Mycroft | November 16, 2011

Do the letters A-R match that trait Volker? :-D

Back on topic, I'm very happy to see Tesla buck the feel-goodness of a useless solar roof. Very few people (once they found out the usefulness of it) would pay the full cost of incorporating a solar roof on the car. I think it's telling that Fisker made the solar roof standard on their car. That's the only way they could pay for the development and implementation of the damn thing.

While a panoramic roof isn't all that "useful", at least it brightens up the interior of the car and makes it feel more open.

BYT | November 16, 2011

You guys put way more thought into this then I have... :)

Mycroft | November 16, 2011

Hey, we have to think about something while waiting for our car. I can't wait for the options and pricing to be posted so we can go all A-R over them! :-D