Off-Grid Commercial Solar Bus

[Buzz]

Never plugs in!!  Seats 12, uses about 700 wh/mile, average.

Licensed and Certified for operation by the state as a general shuttle bus within the City limits of Truth or Consequences, NM.

http://krqe.com/2016/01/28/new-mexico-woman-invents-states-first-solar-powered-bus/

Midnight 250KS charge controller; 2 strings of 20 6-volt Golf Cart batteries (450 AH) for 2 Warp Drive Motors; 1.7KW Solar panels (HMDE)

[Westbranch]

there are other related articles , one of which outlines her hookup to the  PV, that makes one wonder how it all actually can work.  I remember that the panels were/are totally mismatched...  but I give her credit for making it work!

[TomW]

Nice to see folks trying to be a part of the solution rather than just another part of the problem! And on the cheap, to boot.

If they hired a company to do it the bus would cost 3 Million $$ and only run 30 minutes every other day and require an 8 person engineering team to keep it on the road. Or not?

Anyway, nice to see this grass roots stuff.

Tom

[Westbranch]

here are a few more solar buses

http://www.thecivilengineer.org/news-center/latest-news/item/854-tindo-solar-buzz-kayoola

[Buzz]

Here is a better link to "solar buses"  Note none other uses Midnite, and all the others plug into the grid:  https://en.wikipedia.org/wiki/Solar_bus

Westbranch, why are you so snarky?  Feeling threatened?  The panels are all exactly matched, I made them myself. 

[russ_drinkwater]

Wonder what the motors are?
Voltage wise etc?

[Westbranch]

Hi voltage instead of low so the amps aren't as high as if low voltage...   so said one of the articles...

Buzz, no, I am not threatened and not snarky, just a straight shooter, I say it as I see it.

First thing I noticed were the panels on the back of the bus overlapping and shading the adjacent one(s).   That is a big issue as you can lose a lot of your PV power from the slightest shadow, like the leafless branches we have right now..  I suffered from that issue for a few years...

cheers

[Buzz]

Russ, the motors are synced to the batteries--120V each.  Tied in parallel.  A commercial system involves duplicate everything so it keeps going even if one side goes out.

Westbranch, the 4 panels on back are only for the 12V system, so shading isn't a big deal. I would put them on top if shading was an issue. 12V runs the lights (turn signals) and the pump for the swamp cooler off a separate 12V battery.

Tom W, you have a point.  The US Electricar company was grant-funded and produced 22 of these electric shuttlebuses.  They are very well-made, but it took a lot of revisits by the techs before they got it right.  And by then the grant had run out.  They went out of business in 2000.  A few of these Electricar buses are still in operation around the US.  Japan bought the patents and sat on them.

To avoid that 30 minute/every other day runtime issue, I fully charge and then switch to EQ.  I run mostly on surface voltage, except for hills.

[russ_drinkwater]

At my age I need all the surface voltage I can muster!
Seriously I was toying with the idea of dropping a 48 volt dc motor into out suzuki 4x4 ute on the property with 3 panels over the tray and roof! It only needs to do about 5 kms on most days and at times just sits in the shed. Got plenty of panels here for a charging bay as well!

[Buzz]

Westbranch, the use of solar panels for powering a vehicle off-grid is a new field.  There's a lot of supposition that may not be correct.  It's part of the problem-solving process--state a hypothesis, then test it.  Reading in-depth white papers on each bus explains exactly how they are being powered.  The concept of "solar" with them is that solar pv panels input into the grid, then Transit buses return to a barn to recharge from the grid, resulting in a net "solar" charge. Solar Panels on the roof of such bus only extend the range by taking demand off of the drive batteries.

The Solar Buzz is what everyone hopes solar pv as fuel would be:  There is no need to plug in.

My homemade panels differ from commercial in one major respect. My panels are about half as efficient as commercial panels.  So I get 8% charge efficiency while commercial panels are reaching 16% and higher.

Russ, I use a strategy of running the motors with the surface watts of the panels. It relies on current left over when the batteries are fully charged.  The batteries being full, the average 700 watt-hours being produced by the 2Kw in panels would be wasted as heat in the Float stage.  I set the Midnite 250KS to EQ. The result is a Sorta-Supercapacitor powering the drive motors.  The batteries then are only used for shady spots, acceleration and hills.  This commercial shuttle is for stop and go transit, so the golf-cart batteries work great by rebounding and recharging.

If you were to drop an electric motor into your Suzuki, you would want golf-cart batteries for stop-and-go, or LiFePO for longer distances.  There are lots of DIY conversion videos on YouTube.

[Westbranch]

Here  is a link you can dig into about a different conversion.

http://www.xconomy.com/boston/2014/11/21/vecna-cto-builds-solar-powered-volkswagen-bus-and-it-actually-works/

[dgd]

Russ, I use a strategy of running the motors with the surface watts of the panels. It relies on current left over when the batteries are fully charged.  The batteries being full, the average 700 watt-hours being produced by the 2Kw in panels would be wasted as heat in the Float stage.  I set the Midnite 250KS to EQ. The result is a Sorta-Supercapacitor powering the drive motors.  The batteries then are only used for shady spots, acceleration and hills.  This commercial shuttle is for stop and go transit, so the golf-cart batteries work great by rebounding and recharging.

You use some unfamiliar terminology. What is the 'surface watts of the panels' ?
Explain how you access the 'watts' left over?
So from what you say you place the 250ks into EQ after ABSORB is completed?
This would then direct more current to the battery until it reaches the EQ voltage and continue to do so until the EQ timer expires.
Is it at this time that you somehow redirect current from the Classic/batteries to the bus motors? or other storage device?

Do you not use the bus until the batteries are fully charged? ie ABSORB completed? then only use it when bright sky and PVs producing lots of power?  This would mean no bus on cloudy/dull days?

The 'sorta super capacitor' concept interests me, Have you some devices (caps or ?) storing charge that becomes quickly available to  boost the motors?  - a few small lithiums perhaps?

Sorry if I seem a bit confused, I'm trying to get my head around how this power system works to power a bus?
dgd

[Buzz]

Hi dgd, I'm using terminology that makes the pros roll their eyes.  So, lets just keep it basic, then your head won't hurt so bad.

When you look at a Midnite 250KS screen, it gives you a readout of volts, amps and watts coming into the Midnite from the panels and going out to the batteries. My battery bank is a 120v bank, and that's why I use a 250KS.

I start my driving when the battery voltage is around 136v, so, yeah, I left the ABSORB stage quite a few volts ago.  Anything over 126v not stored power, that's surface voltage.  It's just heating the batteries up and causing evaporation of the acid, so I might as well use it for work.

Fast review:  The production, storage and use of dc electricity is by acid-base reactions.  Motors work by sequential on-off spurts of power to electromagnets to make the shaft turn.

I hardwired the Midnite output, the wires, to both the batteries and the motors.  The wires don't distinguish source.  The demand decides where the electricity flows. 

If I demand a little, the panels provide it. They're the "sorta-supercapacitor". There's about 2KW in panels, and a drive on level ground only uses 700wh. If I demand a lot, the batteries add in. 

When the batteries drain, even a little, I don't have "surface voltage" anymore.  The Midnite goes back to BULK.  Since I do stop-and-go driving, every few blocks I'm picking up passengers, so those minutes of stopping get the batteries back to "full". 

I would never see the voltage over 132v (FLOAT) unless I set the Midnite to EQ ATTEMPT. When the battery charge reads anywhere over 132v, I'm off to my next stop.  So, the EQ timer never completes.  If it did, I would just ask for another round of EQ ATTEMPT.

Clouds, shade, position of the sun, don't matter much.  And, I use the bus when there's a call for service.  That's what the batteries are for.

[russ_drinkwater]

The wind sail is a tad too large for me!
Wonder what voltage it runs and hp of the electric motor?

[Westbranch]

Best guess from the quote is between 120V and 136V

My battery bank is a 120v bank, and that's why I use a 250KS.

I start my driving when the battery voltage is around 136v, 

Anything over 126v not stored power, that's surface voltage.   

I hardwired the Midnite output, the wires, to both the batteries and the motors. 

When the batteries drain, even a little,.......  The Midnite goes back to BULK.  Since I do stop-and-go driving,......, so those minutes of stopping get the batteries back to "full". 

I would never see the voltage over 132v (FLOAT) unless I set the Midnite to EQ ATTEMPT. When the battery charge reads anywhere over 132v, I'm off to my next stop. 

Clouds, shade, position of the sun, don't matter much.  And, I use the bus when there's a call for service.  That's what the batteries are for.

If you agree with the 14.4v needed to charge a 12V battery then she should  be upwards of 144 Volts to get a good charge but as she says she has never seen > 136V or is that 132V...??