Solar panel on the roof

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iKaruna

Member
Joined
Feb 14, 2015
Messages
5
I just picked up my i3 this morning, so I'll be checking out this site regularly for the latest i3 comments. Since this is a recommendations for BMW thread (my first posting), I'll limit it to that. I think BMW should put a solar panel on the roof, sorta like the Fiskar. It could power the accessories and possibly charge the battery.
 
Previous threads on the solar panel idea:

http://www.mybmwi3.com/forum/viewtopic.php?f=5&t=1844

http://www.mybmwi3.com/forum/viewtopic.php?f=11&t=1756

Basically, nice idea but it won't charge the traction battery (~400v+). Running a fan would be possible and keeping the 12v battery topped up, but not much use in a garage or under shelter.

Better to put solar panels on your house and charge from there.
 
There's a thread on this already. Consensus, it's not likely worth the added expense or complexity. NOt enough area to do much for the high voltage batteries, and making 400vdc to charge them from some low level PV panel would probably take as much power to convert than actually increase their SOC. It could be used to maybe provide ventilation when hot, but not a big deal.
 
iKaruna said:
I just picked up my i3 this morning, so I'll be checking out this site regularly for the latest i3 comments. Since this is a recommendations for BMW thread (my first posting), I'll limit it to that. I think BMW should put a solar panel solar energy on the roof, sorta like the Fiskar. It could power the accessories and possibly charge the battery.


That's a great idea, by putting solar panels on the roof can increase the efficiency and usefulness.
But will it also effect on the performance like on mileage, pickup or power of the BMW.
 
jadnashuanh said:
There's a thread on this already. Consensus, it's not likely worth the added expense or complexity. NOt enough area to do much for the high voltage batteries, and making 400vdc to charge them from some low level solar PV panel would probably take as much power to convert than actually increase their SOC. It could be used to maybe provide ventilation when hot, but not a big deal.
Thanks for sharing this content and i want to ask one thing i.e. Can we use on grid solar panels in place of batteries?
 
There's at least a couple of ways to use solar panels...augment the power from the grid when the sun is shining, or, if self-contained, be able to store enough energy for your peak and average power needs when the sun is not shining or you need more than you can make at the instant. That usually means batteries to store it. At Niagara Falls between NY state and Ontario, Canada, they use some excess power, when available, to pump water to a reservoir so that they can keep water flowing over the falls for the tourists during the day. IN reality, they can almost stop the flow over the falls when they direct it to the turbines and to the reservoir. There are some major tunnels upstream of the falls that direct water to the turbines below the falls.

The area on the top of the i3 isn't all that much. Modern panels need about 10sqin to produce one watt. The i3 seems to use around 250W/mile. At 60mph, that's one minute. That means 250*60 minutes for an hour, or 15,000W. So, to power the car, at 10sqin per watt, that's an area of 150,000 sqin, or over 1,000sqft...how much do you think you have on the roof?
 
A solar panel on the roof does sound like a good idea but the question still remains if it is going to be functional enough for the car and whether if it work for this particular model.
 
If you're lucky, you might get a peak of 25W/sqft in direct sun, during the best part of the day. That won't happen often, and the roof is not flat, so how you parked it as well as where, would make a big difffernece. Some makers plan the cells to power things like the HVAC to offload a bit of power usage. Today, I don't think you'd gain enough to offset the initial cost over the life of the vehicle. And, if Trump has his way, solar cells will jump in price radically once imported into the USA. Why he thinks that's a great idea, I don't know.
 
The Toyota Prius got a solar roof for powering accessories in Japan, but the US never got it. Apparently it's because the solar roof wouldn't pass US regulations for safety. Not sure how Fisker got away with it.
 
Actually, my 2010 Prius III (USA) has a solar roof, but it's only used to run the cabin fan to try and keep the interior temps the same as outside ambient temp, potentially preventing the HV battery from being heated up too much. I wish it had also charged the 12V battery.
 
The reason electric cars don't have solar roofs is simple. It will on average reduce the range. The weight of the panel and necessary electronics will make the car heavier. The extra electricity you get will not extend the range farther than the weight will reduce the range.

In theory, a day parked in the sun charging the car could add some additional distance to a depleted battery.

A far better option is to add panels to your house.
 
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