Solar Panels to help charge the batteries

I saw something in the 'Ask Nissan' section of this forum, and I liked the idea. I did a bit of looking around, and this is what I came up with.

The new version of the Prius will have a solar roof as an option, but all it does is keep the cabin ventilated when parked int he sun so that the air conditioner doesn't have to work as hard when you get in the car and start driving.

There is a company in California that makes a solar roof conversion kit for the current version of the Prius, sells it for $3500 US, and has a orders backlogged months. They claim it can help Prius drivers get an extra 15 miles per day. I wondered if you have to be driving all day for that to have an affect, and driving all day would mean multiple tanks of fuel, which would mean the panels increased your milage by maybe 5%. However, it sounds like these kits have batteries because they say it converts the Prius to a plug-in car.

Adopting that philosophy, the solar panels would maybe charge the batteries 5% or 10% per day. That would be a substantial amount for people in California and Florida and Arizona....etc.

Sounds like something Nissan probably already has in the works... why wouldn't they?

The funniest part of it all is that people buy new vehicles and keep them parked inside so the dashboard and paint don't fade in the hot sun. Now, they're building cars you're suppsoed to park in the sun. Sounds like a win-win for automakers and paint shops :lol:

Very true... I wouldn't park my brand new Nissan Leaf out in the hot California sun! It'd be parked in my garage... but then the solar panel wouldn't do any good, unless it was removable. Ha, that sounds like another forum topic altogether!

I don't think that a solar panel would do enough to make a difference. Solar panel technology has a long way to go still. The Nissan Leaf would need panels on the hood, roof, trunk, doors and that still wouldn't provide much power as far as propelling the vehicle goes.

What about a solar charger at home to help off-set the cost of higher elect. bills using 220VAC (see my other post about heavy usage charging over 8 hrs)? Even the battery (charger?) manufacturer admits to heavy elect. drain using the 220V option.

That's exactly what I'm saying though.

Solar panels just don't produce enough for the cost. I guess you are right, that at least if you can buy the huge ones and put them on the roof of your house it would help.

But what about this? Most of the time that you're driving your Nissan Leaf it'll be daytime. Then when you're parked at home all night long in the dark, your solar panels are useless.... you'd need some other battery source to save the power until you got home and plugged in the Leaf!

Ah, but your utility company can be thought of as a giant battery. You feed juice into that "battery" from your solar panels during the day, and pull it back out to feed your Leaf at night.

In fact it gets even better. Check with your utility company, but many of them have schedules with prices that vary by the time of day. If so, you might be able to sell your solar power to them at, say, 20 cents/kWh during the day and then buy it back at night for, say, 10 cents/kWh or even less. Those numbers amount to a tidy 100% profit on everything you generate, and you might even be able to do a lot better than that.

Here are actual current numbers from my utility, PG&E, which supplies most of northern California. They have twenty-some different territories with different rates, so your numbers may vary even if you too use PG&E. These are my summer rates with a schedule for people with EVs, assuming you aren't an "excessive" user of electricity:

05.140 cents/kWh Mon-Fri, midnight - 7 AM
10.811 cents/kWh Mon-Fri, 7 AM - 2 PM, 9 PM - midnight
29.583 cents/kWh Mon-Fri, 2 PM - 9 PM

My best solar hours are 9 AM - 5 PM, so I figure PG&E will be paying me between 15 and 20 cents/kWh once I get my Leaf. Naturally I plan to charge on 220V between midnight and 7 AM.

On weekends I won't really get any break for the price differential, because the lowest price applies except for 5 PM - 10 PM.

Basically, if you do the math, rarely is it justifiable to put solar on the roof of your car. The angles are suboptimal, the weight reduces your range, and you could get more range even on the sunniest of days by instead adding extra batteries for less money and less mass.

Solar panels go on the roof of your house, where they belong.

Here, they pay you (or give you credit for) the cost of the excess electricity you generate in a month, but charge you for elect. PLUS distribution.

In the non-TOD rates, the elec. is the same cost at all tiers (about 10 cents), but the distribtion varies from 3 to 23 cents at different tiers.

Solar on the car roof is just a gimmick. I'm fairly sure more carbon is emitted making the PV than you can ever save over the life of the car.

evnow said:

Solar on the car roof is just a gimmick. I'm fairly sure more carbon is emitted making the PV than you can ever save over the life of the car.

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yup, its more for marketing. On the 2010 Prius Pkg 3/4, if you get the sunroof, you get the PV panel, it's used to run a ventilation fan to keep the cabin cooler, that's it's only purpose. Perhaps Nissan will use it the same way, just keep the interior ventilated if you park the Leaf outside during the day.

I power two households, my PHEV Prius, winery and pump my own well-water with the set-up shown here.http://smilingdogsranch.com/priusblog/wp-content/uploads/2010/01/power31.jpg It can be done. Payback time, well depending on electric rates, maybe 10-15yrs...As Kermit said, "It ain't easy (cheap), being green".

scottsim said:

I power two households, my PHEV Prius, winery and pump my own well-water with the set-up shown here.http://smilingdogsranch.com/priusblog/wp-content/uploads/2010/01/power31.jpg It can be done. Payback time, well depending on electric rates, maybe 10-15yrs...As Kermit said, "It ain't easy (cheap), being green".

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Cool setup.

For my northwest cloudy climate, house PV payback is 35 years i.e. never. So I pay extra to get "green" power instead.

KarenRei said:

Basically, if you do the math, rarely is it justifiable to put solar on the roof of your car. The angles are suboptimal, the weight reduces your range, and you could get more range even on the sunniest of days by instead adding extra batteries for less money and less mass.

Solar panels go on the roof of your house, where they belong.

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Take out "the weight reduces your range", and you are correct. In a few months, there will be 'thin-film' panels that weigh next to nothing that could be literally glued on. I agree though that even those would probably not be enough, but I would still love to see the figures. I think those thin-film panels were close to 19%.

evnow said:

Solar on the car roof is just a gimmick. I'm fairly sure more carbon is emitted making the PV than you can ever save over the life of the car.

Click to expand...

Guess you haven't heard about the 'thin-film' panels that have already been sold commercially? They're coming soon to residential. The carbon footprint is non-existent or ultra low in making them. They aren't made like the old silicon ones.

mitch672 said:

evnow said:

Solar on the car roof is just a gimmick. I'm fairly sure more carbon is emitted making the PV than you can ever save over the life of the car.

Click to expand...

yup, its more for marketing. On the 2010 Prius Pkg 3/4, if you get the sunroof, you get the PV panel, it's used to run a ventilation fan to keep the cabin cooler, that's it's only purpose. Perhaps Nissan will use it the same way, just keep the interior ventilated if you park the Leaf outside during the day.

Click to expand...

Nissan said the solar panel is for charging the 'car' battery, and keeping it full.

leaffan said:

evnow said:

Solar on the car roof is just a gimmick. I'm fairly sure more carbon is emitted making the PV than you can ever save over the life of the car.

Click to expand...

Guess you haven't heard about the 'thin-film' panels that have already been sold commercially? They're coming soon to residential. The carbon footprint is non-existent or ultra low in making them. They aren't made like the old silicon ones.

Click to expand...

Of course, they make an even less significant amount of energy.

leaffan said:

Guess you haven't heard about the 'thin-film' panels that have already been sold commercially? They're coming soon to residential. The carbon footprint is non-existent or ultra low in making them. They aren't made like the old silicon ones.

Click to expand...

LOL. Don't go by hype.

What is the EROEI of thin films, installed ? In Seattle definitely not much more than 1.

evnow said:

leaffan said:

Guess you haven't heard about the 'thin-film' panels that have already been sold commercially? They're coming soon to residential. The carbon footprint is non-existent or ultra low in making them. They aren't made like the old silicon ones.

Click to expand...

LOL. Don't go by hype.

What is the EROEI of thin films, installed ? In Seattle definitely not much more than 1.

Click to expand...

EROEI for thin films is generally reported in terms of months.

FirstSolar thin films are available for residential consumers. Nanosolar are only available in limited quantities to commercial consumers. Nanosolar's are better, but they're having a harder time with scaling up.

Actually, I keep fantasizing about one possible way to use thin film for direct Leaf charging. Let's say I store a bunch of light-weight interconnectible aluminum tubes in the back of my Leaf, since I have no use for the golf clubs they so often brag about. When I get to the parking lot where I'm going to leave my car all day, I put together a sort of temporary 10x20 foot carport around my beauty, and cover it, top and sides, with thin film solar sheets. Now I've got my car shaded, the paint protected, and as much energy coming in as about 200 sq ft (adjusted for tilt) of those sheets can provide.

Hey, I haven't figured the watt-hours, but it's gotta count for something.

KarenRei said:

Nanosolar are only available in limited quantities to commercial consumers. Nanosolar's are better, but they're having a harder time with scaling up.

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Nano is just hype - over promise, under deliver. I don't like such guys. Probably same goes for the whole thin film industry.

http://seekingalpha.com/article/196248-will-thin-film-ever-meet-expectations

leaffan said:

Nissan said the solar panel is for charging the 'car' battery, and keeping it full.

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For a solar panel sanity check, first look at the VW solar panelsdealers use to maintain the 12V starter battery when cars sit on the lot.

This small panel makes a max of about 18V at most 170mA - 0.17A.

Compare the dimensions of this small panel with the surface area of the small panel on the Leaf.

A panel this size won't keep up with the drain on a car battery from alarms, keyless entry receivers, and lead-acid self discharge, much less do anything for the traction pack.

(VW dealers often toss these chargers so no need to pay for one from an ebay seller if you want one to play with.)

Andy