Re: [EVDL] Light-weight 100W PV roof panel for 48V e-carts> ?Is it worth it?

[Mike Nickerson via EV]

I don't think you can look at it that way, since the asset (the solar array) is 
depreciating.  You can't get that return for ten years, then get your money 
back to invest elsewhere.

It would be more appropriate to view this as a payback period.  The time for 
the savings to cover the cost of the original investment is 25-100 years.  
Seems awfully long.  Will it last that long?

Generally, you want a payback period that is within your expected usage life, 
and the item's physical life, if you are buying it for financial return.  5-10 
years payback period are pretty common goals.

Mike

On September 22, 2015 10:55:05 AM MDT, Robert Bruninga via EV 
 wrote:
>> Sounds like yearly payback is somewhere between $10.00 and $40.00.
>> Sounds kind of small for an investment of more than $1000.
>
>That's 1% to 4%.  Better than most banks.  And FAR better for the
>future
>since it displaces X amount of coal burning.
>
>So if it is equal or better than most other investments, AND it is
>definitely better than using coal electricity for ALL of us, then many
>would jump at the chance.
>
>Bob
>
>On September 22, 2015 7:19:43 AM MDT, EVDL Administrator via EV
> wrote:
>>On 22 Sep 2015 at 3:50, brucedp5 via EV wrote:
>>
>>> ? Is this a useful product worthy of the co$t, or is it a profitable
>>> feel-good add-on for bragging-rights ?
>>
>>Much of the answer is right in the story:
>>
>>> As a yearly average, the system generates 29 percent of the total
>>energy
>>> required to drive eight miles per day in West Palm Beach, Fla. That
>>reduces
>>> the energy needed to recharge the battery by 29 percent. Results may
>>vary
>>> depending on area and usage.
>>>
>>> By continually transferring energy to the batteries, the panels
>limit
>>how deep
>>> into the battery reserve a vehicle must go during a typical use.
>>
>>I suspect this is a best-case estimate.  Let's run some numbers.
>>
>>First let me warn you that there's a fair bit of hand-waving here. 
>I'm
>>not an expert in these matters.  If you're a PV expert and can come up
>>with
>>
>>better numbers than mine, by all means please do so.
>>
>>IIRC a typical golf car range is around 40-50 miles.  Using standard
>>T105
>>type batteries this amounts to an energy usage of between 126 and 158
>>Wh/mi.
>>Let's call it 150 Wh/mi for convenience.
>>
>>Driving 8 miles per day will require 1200 WH per day or (1200 * 365)
>==
>>
>>438000 Wh/year if you drive the car every day (as the PR release seems
>>to suggest).
>>
>>This panel can produce 100 watts, but if that's a typical rating it'll
>>only apply when the golf car is parked in the sun with the sun
>directly
>>overhead.
>>At other times the output will be lower, but I'm not a solar expert so
>>I don't know by how much.  I'll take a wild guess and estimate that
>the
>>panel will average 30 watts over an average day's sunshine (including
>>dawn and dusk).  Someone please correct me if that's too far off.
>>
>>So that's 30W * 12h == 360 Wh/day * 234 days (average sunny days per
>>year in West Palm Beach) == 84240 Wh/year.  This is 19% of the energy
>>required to drive 8 miles per day, about a third less than Club Car
>>claim, but surprisingly close.
>>
>>But even my 19% estimate assumes the golf car will be in the sun any
>>time the sun is shining.  If you park it in a garage, or in the shade
>>of a building or tree, it gains little or nothing.  How many people
>>deliberately park their cars (golf or otherwise) in the sun on a hot
>>summer day in Florida?
>>
>>Other factors will affect solar gain.  For example, if you drive it on
>>a tree lined street, or a city street with tall buildings around it,
>it
>>will gain less solar energy.
>>
>>So, is this just a "feel-good add-on"?  Well ... as with any other
>>vehicle option, how much a given user gains from this one depends on
>>where and how she drives.  But for most users, I'd say it'll probably
>>yield more bragging rights than range.
>>
>>What it MIGHT do that's potentially at least as useful -- IF you park
>>mostly in the sun --- is dribble a little charge back into the battery
>>when the car isn't being driven.  That'll improve battery cycle life a
>>bit.
>>Calculating
>>whether the resulting battery cost savings will offset the cost of the
>>PV panel will be left as an exercise for the reader. ;-)
>>
>>FWIW, in looking for info on this I ran across several dealers
>offering
>>
>>aftermarket PV panel options for golf cars.  One claimed a (peak)
>>output of
>>220 watts.  The price was $1450.
>>
>>Is it worth it?  I see 12v 50w generic PV panels on Ebay for around
>>$100
>>each.  Five of them would give you peak 250W into a charge controller.
>>
>>Speaking of which, I see 48v, 30-45 amp charge controllers on Ebay at
>>prices from $160 to $260.
>>
>>The dealer I mentioned above also provide a roof frame and struts.
>>What do
>>you think that's worth, maybe $150?   So they're making around $700 on
>>each
>>kit.  That's a 100% return on the 

Re: [EVDL] Light-weight 100W PV roof panel for 48V e-carts> ?Is it worth it?

[Ben Goren via EV]

On Sep 22, 2015, at 1:52 PM, Lee Hart  wrote:

> Ben Goren via EV wrote:
> 
>> Not just current state of the art...it's never going to be practical
>> for the four-door five-passenger freeway sedan that dominates the
>> roadways; there just isn't enough insolation.
> 
> I agree for normal cars. But I have to wonder... what about railroad cars?

Now that's a _very_ interesting thought!

One would have to run the numbers, of course, which shouldn't be too difficult: 
box car surface area, assume panels laid flat on top and average US insolation. 
Locomotive fuel consumption per mile should be easy to find.

If the math works, it should be straightforward to retrofit...the locomotives 
are already electric vehicles with diesel generators providing the electricity. 
Add a battery car, charge the batteries from the panels, run the electric motor 
from the batteries, and keep the diesel generator to top off the batteries if 
they ever run low. I'd think the biggest technical challenge would be routing 
that much power from car to car...every car would have to be able to carry the 
full current of the maximum output from the panels, over a connection that can 
be made and disconnected at random times, quickly and safely -- and with 
automatic shutdown / disconnect in case of derailment or other emergency. I bet 
that wouldn't be easy to design nor cheap to implement.

...but, alas, a significant fraction of rail transport is moving fossil fuels 
around the country, and something tells me that the rail owners would get upset 
at the "optics" of a solar-powered train hauling coal or tar sands crude. If 
solar is what's best for the trains moving the dirty stuff, why bother with the 
dirty stuff in the first place, and why not just go solar everywhere?

Don't hold your breath, in other words.

b&
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Re: [EVDL] Light-weight 100W PV roof panel for 48V e-carts> ?Is it worth it?

[Robert Bruninga via EV]

> Sounds like yearly payback is somewhere between $10.00 and $40.00.
> Sounds kind of small for an investment of more than $1000.

That's 1% to 4%.  Better than most banks.  And FAR better for the future
since it displaces X amount of coal burning.

So if it is equal or better than most other investments, AND it is
definitely better than using coal electricity for ALL of us, then many
would jump at the chance.

Bob

On September 22, 2015 7:19:43 AM MDT, EVDL Administrator via EV
 wrote:
>On 22 Sep 2015 at 3:50, brucedp5 via EV wrote:
>
>> ? Is this a useful product worthy of the co$t, or is it a profitable
>> feel-good add-on for bragging-rights ?
>
>Much of the answer is right in the story:
>
>> As a yearly average, the system generates 29 percent of the total
>energy
>> required to drive eight miles per day in West Palm Beach, Fla. That
>reduces
>> the energy needed to recharge the battery by 29 percent. Results may
>vary
>> depending on area and usage.
>>
>> By continually transferring energy to the batteries, the panels limit
>how deep
>> into the battery reserve a vehicle must go during a typical use.
>
>I suspect this is a best-case estimate.  Let's run some numbers.
>
>First let me warn you that there's a fair bit of hand-waving here.  I'm
>not an expert in these matters.  If you're a PV expert and can come up
>with
>
>better numbers than mine, by all means please do so.
>
>IIRC a typical golf car range is around 40-50 miles.  Using standard
>T105
>type batteries this amounts to an energy usage of between 126 and 158
>Wh/mi.
>Let's call it 150 Wh/mi for convenience.
>
>Driving 8 miles per day will require 1200 WH per day or (1200 * 365) ==
>
>438000 Wh/year if you drive the car every day (as the PR release seems
>to suggest).
>
>This panel can produce 100 watts, but if that's a typical rating it'll
>only apply when the golf car is parked in the sun with the sun directly
>overhead.
>At other times the output will be lower, but I'm not a solar expert so
>I don't know by how much.  I'll take a wild guess and estimate that the
>panel will average 30 watts over an average day's sunshine (including
>dawn and dusk).  Someone please correct me if that's too far off.
>
>So that's 30W * 12h == 360 Wh/day * 234 days (average sunny days per
>year in West Palm Beach) == 84240 Wh/year.  This is 19% of the energy
>required to drive 8 miles per day, about a third less than Club Car
>claim, but surprisingly close.
>
>But even my 19% estimate assumes the golf car will be in the sun any
>time the sun is shining.  If you park it in a garage, or in the shade
>of a building or tree, it gains little or nothing.  How many people
>deliberately park their cars (golf or otherwise) in the sun on a hot
>summer day in Florida?
>
>Other factors will affect solar gain.  For example, if you drive it on
>a tree lined street, or a city street with tall buildings around it, it
>will gain less solar energy.
>
>So, is this just a "feel-good add-on"?  Well ... as with any other
>vehicle option, how much a given user gains from this one depends on
>where and how she drives.  But for most users, I'd say it'll probably
>yield more bragging rights than range.
>
>What it MIGHT do that's potentially at least as useful -- IF you park
>mostly in the sun --- is dribble a little charge back into the battery
>when the car isn't being driven.  That'll improve battery cycle life a
>bit.
>Calculating
>whether the resulting battery cost savings will offset the cost of the
>PV panel will be left as an exercise for the reader. ;-)
>
>FWIW, in looking for info on this I ran across several dealers offering
>
>aftermarket PV panel options for golf cars.  One claimed a (peak)
>output of
>220 watts.  The price was $1450.
>
>Is it worth it?  I see 12v 50w generic PV panels on Ebay for around
>$100
>each.  Five of them would give you peak 250W into a charge controller.
>
>Speaking of which, I see 48v, 30-45 amp charge controllers on Ebay at
>prices from $160 to $260.
>
>The dealer I mentioned above also provide a roof frame and struts.
>What do
>you think that's worth, maybe $150?   So they're making around $700 on
>each
>kit.  That's a 100% return on the parts cost.  Not too shabby.
>
>David Roden - Akron, Ohio, USA
>EVDL Administrator
>
>= = = = = = = = = = = = = = = = = = = = = = = = = = = = = EVDL
>Information: http://www.evdl.org/help/ = = = = = = = = = = = = = = = =
>= = = = = = = = = = = = =
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>To send a private message, please obtain my email address from the
>webpage http://www.evdl.org/help/ .
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>
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Re: [EVDL] Light-weight 100W PV roof panel for 48V e-carts> ?Is it worth it?

[Ben Goren via EV]

On Sep 22, 2015, at 9:55 AM, Robert Bruninga via EV  wrote:

> That's 1% to 4%.  Better than most banks.  And FAR better for the future
> since it displaces X amount of coal burning.

If that's your goal, _far_ better to put the panels on your rooftop and 
backfeed into the grid -- assuming, of course, your utility provides a 
reasonable variation on the net metering theme. If not...I'll bet a cup of 
coffee that stationary panels going to a set of batteries used as a dump pack 
for the golf cart would still financially outperform the roof-mounted option. 
You can use cheaper panels that get maximum insolation, and the only concern 
for the dump pack is total lifetime cost per kWh in and out -- weight or volume 
or similar concerns are irrelevant.

A significant fraction of the electric vehicles on the road are already solar 
powered; EV owners are statistically much more likely to have rooftop solar 
generation than others. Except as a gimmick or an engineering challenge or in 
unreal fringe cases (extraterrestrial planetary exploration), carting the 
panels around with you is the most over-the-top wasteful way to get to a 
"green" car. It's pure conspicuous consumerism --which is perfectly fine if you 
can afford and appreciate the luxury...just don't pretend that it's saving the 
planet or that it makes good financial sense.

b&
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Re: [EVDL] Light-weight 100W PV roof panel for 48V e-carts> ?Is it worth it?

[Mark Abramowitz via EV]

Most investments pay more than that. Using bank interest as an indication in 
this low interest rate environment isn't appropriate.



Sent from my iPhone

On Sep 22, 2015, at 9:55 AM, Robert Bruninga via EV  wrote:

>> Sounds like yearly payback is somewhere between $10.00 and $40.00.
>> Sounds kind of small for an investment of more than $1000.
> 
> That's 1% to 4%.  Better than most banks.  And FAR better for the future
> since it displaces X amount of coal burning.
> 
> So if it is equal or better than most other investments, AND it is
> definitely better than using coal electricity for ALL of us, then many
> would jump at the chance.
> 
> Bob
> 
> On September 22, 2015 7:19:43 AM MDT, EVDL Administrator via EV
>  wrote:
>> On 22 Sep 2015 at 3:50, brucedp5 via EV wrote:
>> 
>>> ? Is this a useful product worthy of the co$t, or is it a profitable
>>> feel-good add-on for bragging-rights ?
>> 
>> Much of the answer is right in the story:
>> 
>>> As a yearly average, the system generates 29 percent of the total
>> energy
>>> required to drive eight miles per day in West Palm Beach, Fla. That
>> reduces
>>> the energy needed to recharge the battery by 29 percent. Results may
>> vary
>>> depending on area and usage.
>>> 
>>> By continually transferring energy to the batteries, the panels limit
>> how deep
>>> into the battery reserve a vehicle must go during a typical use.
>> 
>> I suspect this is a best-case estimate.  Let's run some numbers.
>> 
>> First let me warn you that there's a fair bit of hand-waving here.  I'm
>> not an expert in these matters.  If you're a PV expert and can come up
>> with
>> 
>> better numbers than mine, by all means please do so.
>> 
>> IIRC a typical golf car range is around 40-50 miles.  Using standard
>> T105
>> type batteries this amounts to an energy usage of between 126 and 158
>> Wh/mi.
>> Let's call it 150 Wh/mi for convenience.
>> 
>> Driving 8 miles per day will require 1200 WH per day or (1200 * 365) ==
>> 
>> 438000 Wh/year if you drive the car every day (as the PR release seems
>> to suggest).
>> 
>> This panel can produce 100 watts, but if that's a typical rating it'll
>> only apply when the golf car is parked in the sun with the sun directly
>> overhead.
>> At other times the output will be lower, but I'm not a solar expert so
>> I don't know by how much.  I'll take a wild guess and estimate that the
>> panel will average 30 watts over an average day's sunshine (including
>> dawn and dusk).  Someone please correct me if that's too far off.
>> 
>> So that's 30W * 12h == 360 Wh/day * 234 days (average sunny days per
>> year in West Palm Beach) == 84240 Wh/year.  This is 19% of the energy
>> required to drive 8 miles per day, about a third less than Club Car
>> claim, but surprisingly close.
>> 
>> But even my 19% estimate assumes the golf car will be in the sun any
>> time the sun is shining.  If you park it in a garage, or in the shade
>> of a building or tree, it gains little or nothing.  How many people
>> deliberately park their cars (golf or otherwise) in the sun on a hot
>> summer day in Florida?
>> 
>> Other factors will affect solar gain.  For example, if you drive it on
>> a tree lined street, or a city street with tall buildings around it, it
>> will gain less solar energy.
>> 
>> So, is this just a "feel-good add-on"?  Well ... as with any other
>> vehicle option, how much a given user gains from this one depends on
>> where and how she drives.  But for most users, I'd say it'll probably
>> yield more bragging rights than range.
>> 
>> What it MIGHT do that's potentially at least as useful -- IF you park
>> mostly in the sun --- is dribble a little charge back into the battery
>> when the car isn't being driven.  That'll improve battery cycle life a
>> bit.
>> Calculating
>> whether the resulting battery cost savings will offset the cost of the
>> PV panel will be left as an exercise for the reader. ;-)
>> 
>> FWIW, in looking for info on this I ran across several dealers offering
>> 
>> aftermarket PV panel options for golf cars.  One claimed a (peak)
>> output of
>> 220 watts.  The price was $1450.
>> 
>> Is it worth it?  I see 12v 50w generic PV panels on Ebay for around
>> $100
>> each.  Five of them would give you peak 250W into a charge controller.
>> 
>> Speaking of which, I see 48v, 30-45 amp charge controllers on Ebay at
>> prices from $160 to $260.
>> 
>> The dealer I mentioned above also provide a roof frame and struts.
>> What do
>> you think that's worth, maybe $150?   So they're making around $700 on
>> each
>> kit.  That's a 100% return on the parts cost.  Not too shabby.
>> 
>> David Roden - Akron, Ohio, USA
>> EVDL Administrator
>> 
>> = = = = = = = = = = = = = = = = = = = = = = = = = = = = = EVDL
>> Information: http://www.evdl.org/help/ = = = = = = = = = = = = = = = =
>> = = = = = = = = = = = = =
>> Note: mail sent to "evpost" and "etpost" addresses will not reach me.
>> To send a private 

Re: [EVDL] Light-weight 100W PV roof panel for 48V e-carts> ?Is it worth it?

[Ben Goren via EV]

On Sep 22, 2015, at 11:46 AM, EVDL Administrator via EV  
wrote:

> The autonomous onboard-PV EV is a sweet dream.  Who wouldn't love to drive
> on pure sunshine and never have to fuel up or plug in?  But at the current
> state of the art, that's your heart talking, not your head.

Not just current state of the art...it's never going to be practical for the 
four-door five-passenger freeway sedan that dominates the roadways; there just 
isn't enough insolation. The Nissan Leaf already fits that bill, save with 
rooftop solar and a limited range -- and the Tesla is perhaps the best luxury 
performance sedan ever made. So what sort of sense does it make to restrict 
yourself to a prone position in a sardine can that can't be garaged and can 
only be driven in the open on sunny days...just so you can have the privilege 
of hauling around an expensive and fragile kluge of a portable solar array?

Again, fantastic for the bragging rights, the engineering challenge, all the 
rest. But it'll never be anything other than a gimmick, even long after the 
majority of the cars on the road are solar powered.

b&
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Re: [EVDL] Light-weight 100W PV roof panel for 48V e-carts> ?Is it worth it?

[Robert Bruninga via EV]

-Original Message-
>> That's 1% to 4%.  Better than most banks.  And FAR better for the
>> future since it displaces X amount of coal burning.

> I'll bet a cup of coffee that stationary panels going to a set of
batteries used as a dump pack for the golf cart would still financially
outperform the roof-mounted option.

When Can I collect the cup?

Only if the Golf Cart and dump-pack are FULLY discharged every day.
Because only then are you using the solar panels.  A solar panel just
sitting there in the sun connected to a fully charged battery is providing
ZERO return on investment.

That is why NET metering is the best economics hands down.  You get 100%
of the energy all the time, every day, no matter how much you use.

People forget that battery systems are not only very inefficient, require
maintenqance, but whenever they are fully charged, then the solar panels
are providing nothing in return for their investment.  And since battery
systems have to have oversized solar panels to make up for cloudy days,
then by definition, every fully sun day, then all the excess solar energy
beyond full charge is simply wasted.

My conclusion is that any use of batteries for storing solar energy wastes
$2 of every $3 invested in the solar system.  Grid-tie wastes none of it.
You get full retail value for every watt that falls on the panels no
matter where you use it.

Bob, WB4APR

You can use cheaper panels that get maximum insolation, and the only
concern for the dump pack is total lifetime cost per kWh in and out --
weight or volume or similar concerns are irrelevant.

A significant fraction of the electric vehicles on the road are already
solar powered; EV owners are statistically much more likely to have
rooftop solar generation than others. Except as a gimmick or an
engineering challenge or in unreal fringe cases (extraterrestrial
planetary exploration), carting the panels around with you is the most
over-the-top wasteful way to get to a "green" car. It's pure conspicuous
consumerism --which is perfectly fine if you can afford and appreciate the
luxury...just don't pretend that it's saving the planet or that it makes
good financial sense.

b&
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Re: [EVDL] Light-weight 100W PV roof panel for 48V e-carts> ?Is it worth it?

[Ben Goren via EV]

On Sep 22, 2015, at 12:12 PM, Robert Bruninga via EV  wrote:

> Only if the Golf Cart and dump-pack are FULLY discharged every day.

Hmmm...I don't think that's quite right, but the basic point you make is a good 
one. If the car has, say, a 300 mile range, and the fixed generation system 
makes an average of 50 miles of range per day and you drive an average of 50 
miles per day, that's going to be pretty much optimal -- even though the 
batteries are never going below 80% of full charge.

> That is why NET metering is the best economics hands down.

Fully agreed -- but, of course, only where it's an option. It's the rate plan 
I'm personally on. However, thanks to intense private lobbying by the Koch 
Brothers...were my neighbors to install similar systems today, though they'd 
technically be on a net metering rate plan, they'd actually wind up spending 
80% of whatever they do today regardless of how much net they generate. The new 
plans have insane instantaneous peak / load factor / etc. surcharges that're 
guaranteed to make rooftop solar a complete waste of money.

Utilities are doing this in a _very_ shortsighted attempt to prevent grid 
defection...but it's too late. Already, my neighbors would have about the same 
return on investment if they cut the grid connection and went to batteries as 
they would have a couple decades ago with grid-tie solar. The cost of a grid 
connection for new construction is so insane that it can't even pretend to 
compete with battery-backed solar; the grid hookup alone can cost more than the 
batteries, maybe even more than the total solar+battery installation cost -- 
and that's before you consider the value of a lifetime of free unmetered energy.

So...the grid is going to die, and it's the utilities themselves that are going 
to kill it. It's a shame...but at least we all get limitless free electricity 
(after initial capital investment) no matter what happens to the grid.

Cheers,

b&
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Re: [EVDL] Light-weight 100W PV roof panel for 48V e-carts> ?Is it worth it?

[EVDL Administrator via EV]

On 22 Sep 2015 at 11:28, Ben Goren via EV wrote:

> carting the panels around with you is the most over-the-top wasteful
> way to get to a "green" car. 

It worsens your vehicle's aerodynamics, too.  Not only are you wasting 
energy you could harvest by leaving the PVs at home, you're also throwing it 
away in additional aero drag.

> It's pure conspicuous consumerism ...

I wouldn't go that far, but IMO it's not the best use of the resources 
(financial and otherwise) involved.

The autonomous onboard-PV EV is a sweet dream.  Who wouldn't love to drive 
on pure sunshine and never have to fuel up or plug in?  But at the current 
state of the art, that's your heart talking, not your head.

David Roden - Akron, Ohio, USA
EVDL Administrator

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Re: [EVDL] Light-weight 100W PV roof panel for 48V e-carts> ?Is it worth it?

[Mike Nickerson via EV]

Let me take the math another direction.

It looks like David calculated a net gain of about 84,000 Wh per year.  Let's 
round that up to 100,000 Wh per year.  That is 100 kWh.  Assuming electricity 
costs somewhere between $0.10 and $0.40 per kWh.  Sounds like yearly payback is 
somewhere between $10.00 and $40.00.

Sounds kind of small for an investment of more than $1000.

Mike


On September 22, 2015 7:19:43 AM MDT, EVDL Administrator via EV 
 wrote:
>On 22 Sep 2015 at 3:50, brucedp5 via EV wrote:
>
>> ? Is this a useful product worthy of the co$t, or is it a profitable
>> feel-good add-on for bragging-rights ? 
>
>Much of the answer is right in the story:
>
>> As a yearly average, the system generates 29 percent of the total
>energy
>> required to drive eight miles per day in West Palm Beach, Fla. That
>reduces
>> the energy needed to recharge the battery by 29 percent. Results may
>vary
>> depending on area and usage. 
>> 
>> By continually transferring energy to the batteries, the panels limit
>how deep
>> into the battery reserve a vehicle must go during a typical use.
>
>I suspect this is a best-case estimate.  Let's run some numbers.
>
>First let me warn you that there's a fair bit of hand-waving here.  I'm
>not 
>an expert in these matters.  If you're a PV expert and can come up with
>
>better numbers than mine, by all means please do so.
>
>IIRC a typical golf car range is around 40-50 miles.  Using standard
>T105 
>type batteries this amounts to an energy usage of between 126 and 158
>Wh/mi.
>Let's call it 150 Wh/mi for convenience.  
>
>Driving 8 miles per day will require 1200 WH per day or (1200 * 365) ==
>
>438000 Wh/year if you drive the car every day (as the PR release seems
>to 
>suggest).
>
>This panel can produce 100 watts, but if that's a typical rating it'll
>only 
>apply when the golf car is parked in the sun with the sun directly
>overhead. 
>At other times the output will be lower, but I'm not a solar expert so
>I 
>don't know by how much.  I'll take a wild guess and estimate that the
>panel 
>will average 30 watts over an average day's sunshine (including dawn
>and 
>dusk).  Someone please correct me if that's too far off.
>
>So that's 30W * 12h == 360 Wh/day * 234 days (average sunny days per
>year in 
>West Palm Beach) == 84240 Wh/year.  This is 19% of the energy required
>to 
>drive 8 miles per day, about a third less than Club Car claim, but 
>surprisingly close.
>
>But even my 19% estimate assumes the golf car will be in the sun any
>time 
>the sun is shining.  If you park it in a garage, or in the shade of a 
>building or tree, it gains little or nothing.  How many people
>deliberately 
>park their cars (golf or otherwise) in the sun on a hot summer day in 
>Florida?
>
>Other factors will affect solar gain.  For example, if you drive it on
>a 
>tree lined street, or a city street with tall buildings around it, it
>will 
>gain less solar energy.  
>
>So, is this just a "feel-good add-on"?  Well ... as with any other
>vehicle 
>option, how much a given user gains from this one depends on where and
>how 
>she drives.  But for most users, I'd say it'll probably yield more
>bragging 
>rights than range.
>
>What it MIGHT do that's potentially at least as useful -- IF you park
>mostly 
>in the sun --- is dribble a little charge back into the battery when
>the car 
>isn't being driven.  That'll improve battery cycle life a bit. 
>Calculating 
>whether the resulting battery cost savings will offset the cost of the
>PV 
>panel will be left as an exercise for the reader. ;-)
>
>FWIW, in looking for info on this I ran across several dealers offering
>
>aftermarket PV panel options for golf cars.  One claimed a (peak)
>output of 
>220 watts.  The price was $1450.  
>
>Is it worth it?  I see 12v 50w generic PV panels on Ebay for around
>$100 
>each.  Five of them would give you peak 250W into a charge controller. 
>
>Speaking of which, I see 48v, 30-45 amp charge controllers on Ebay at  
>prices from $160 to $260.  
>
>The dealer I mentioned above also provide a roof frame and struts. 
>What do 
>you think that's worth, maybe $150?   So they're making around $700 on
>each 
>kit.  That's a 100% return on the parts cost.  Not too shabby.  
>
>David Roden - Akron, Ohio, USA
>EVDL Administrator
>
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>
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Re: [EVDL] Light-weight 100W PV roof panel for 48V e-carts> ?Is it worth it?

[Cor van de Water via EV]

Bob,
I think the comparison of dump pack versus roof mounted option
was comparing a house mounted solar+dump solution to a *car*roof mounted solar 
panel,
which is easy to beat in financial terms due to the cost of flexible solar
for car roof and the unreliable insolation on a car.
Other attempts at this have constructed car charging car ports to get increased
efficiency from solar panels other than on the car itself.

Cor van de Water
Chief Scientist
Proxim Wireless

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-Original Message-
From: EV [mailto:ev-boun...@lists.evdl.org] On Behalf Of Robert Bruninga via EV
Sent: Tuesday, September 22, 2015 12:13 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Light-weight 100W PV roof panel for 48V e-carts> ?Is it 
worth it?

-Original Message-
>> That's 1% to 4%.  Better than most banks.  And FAR better for the 
>> future since it displaces X amount of coal burning.

> I'll bet a cup of coffee that stationary panels going to a set of
batteries used as a dump pack for the golf cart would still financially 
outperform the roof-mounted option.

When Can I collect the cup?

Only if the Golf Cart and dump-pack are FULLY discharged every day.
Because only then are you using the solar panels.  A solar panel just sitting 
there in the sun connected to a fully charged battery is providing ZERO return 
on investment.

That is why NET metering is the best economics hands down.  You get 100% of the 
energy all the time, every day, no matter how much you use.

People forget that battery systems are not only very inefficient, require 
maintenqance, but whenever they are fully charged, then the solar panels are 
providing nothing in return for their investment.  And since battery systems 
have to have oversized solar panels to make up for cloudy days, then by 
definition, every fully sun day, then all the excess solar energy beyond full 
charge is simply wasted.

My conclusion is that any use of batteries for storing solar energy wastes
$2 of every $3 invested in the solar system.  Grid-tie wastes none of it.
You get full retail value for every watt that falls on the panels no matter 
where you use it.

Bob, WB4APR

You can use cheaper panels that get maximum insolation, and the only concern 
for the dump pack is total lifetime cost per kWh in and out -- weight or volume 
or similar concerns are irrelevant.

A significant fraction of the electric vehicles on the road are already solar 
powered; EV owners are statistically much more likely to have rooftop solar 
generation than others. Except as a gimmick or an engineering challenge or in 
unreal fringe cases (extraterrestrial planetary exploration), carting the 
panels around with you is the most over-the-top wasteful way to get to a 
"green" car. It's pure conspicuous consumerism --which is perfectly fine if you 
can afford and appreciate the luxury...just don't pretend that it's saving the 
planet or that it makes good financial sense.

b&
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Re: [EVDL] Light-weight 100W PV roof panel for 48V e-carts> ?Is it worth it?

[Lawrence Harris via EV]

It’s an interesting problem that I believe has a moving target since in
some places you get paid retail for your excess electrons but in other
jurisdictions you get paid a fraction of retail.  The power companies
if they had their way would pay a pittance for your excess and then
sell you back the electrons at retail.

There is some justification for this since they don’t always need
your excess.  Having too much excess power but no control over
when it’s being offered can be a big problem.  If you have a bright
windy day and lots of solar and wind being dumped into the grid
and then get a sudden drop in wind and a cloud rolling overhead
the system will need to have peaking plants on standby to take
over the load.  Idling these plants is expensive, maybe more
so than just suppling the power from traditional sources.

A grid that had distributed power storage and access to several ideally
clean energy sources would end up being the most stable.  If you have
your own battery bank you can keep the lights on during a power failures
for sure but you can also run on your own ‘free’ electrons, sell the excess
to the grid if you have them, buy them back if you need them but maybe
at a lower off peak rate and potentially offer them back at a premium if the
grid asks for them.

This would allow for basically five price points:
$0.00   You don’t need the grid, the grid does not need you.
Here the grid is operating below optimal with room to move up but
not down.

$low-buyYou do need the grid, the grid has excess.
Here the grid is operating below optimal and can efficiently offer
you more electrons.

$high-buy   You do need the grid, the grid is peaking.
Here you have run low and the grid is operating above optimal
and drawing on other, maybe stored sources to make up the difference.

$low-sell   You have excess and the grid has the capacity to accept.
Here you have excess and the grid is operating above optimal and
can save money buy accepting your extra.

$high-sell  You have excess and the grid is peaking so needs extra.
Here you have extra and the grid is peaking and requesting extra
from stored sources, you offer some of your stored energy in
exchange for a higher value.

So in my estimation it is the bi-directional grid tie with with distributed
local storage and net metering is a the win-win situation.

There was a lot of discussion some time back about Vehicle to Grid
(VTG) solutions where electric cars become part of the distributed
storage.  If you integrate vehicles and possibly stationary batteries
you could reach a point where there was enough storage to shut
down some of the dirty generating stations entirely, not just the peaking
plants.

Lawrence


> On Sep 22, 2015, at 12:12 PM, Robert Bruninga via EV  
> wrote:
> 
> -Original Message-
>>> That's 1% to 4%.  Better than most banks.  And FAR better for the
>>> future since it displaces X amount of coal burning.
> 
>> I'll bet a cup of coffee that stationary panels going to a set of
> batteries used as a dump pack for the golf cart would still financially
> outperform the roof-mounted option.
> 
> When Can I collect the cup?
> 
> Only if the Golf Cart and dump-pack are FULLY discharged every day.
> Because only then are you using the solar panels.  A solar panel just
> sitting there in the sun connected to a fully charged battery is providing
> ZERO return on investment.
> 
> That is why NET metering is the best economics hands down.  You get 100%
> of the energy all the time, every day, no matter how much you use.
> 
> People forget that battery systems are not only very inefficient, require
> maintenqance, but whenever they are fully charged, then the solar panels
> are providing nothing in return for their investment.  And since battery
> systems have to have oversized solar panels to make up for cloudy days,
> then by definition, every fully sun day, then all the excess solar energy
> beyond full charge is simply wasted.
> 
> My conclusion is that any use of batteries for storing solar energy wastes
> $2 of every $3 invested in the solar system.  Grid-tie wastes none of it.
> You get full retail value for every watt that falls on the panels no
> matter where you use it.
> 
> Bob, WB4APR
> 
> You can use cheaper panels that get maximum insolation, and the only
> concern for the dump pack is total lifetime cost per kWh in and out --
> weight or volume or similar concerns are irrelevant.
> 
> A significant fraction of the electric vehicles on the road are already
> solar powered; EV owners are statistically much more likely to have
> rooftop solar generation than others. Except as a gimmick or an
> engineering challenge or in unreal fringe cases (extraterrestrial
> planetary exploration), carting the panels around with you is the most
> over-the-top wasteful way to get to a "green" car. 

Re: [EVDL] Light-weight 100W PV roof panel for 48V e-carts> ?Is it worth it?

[Lee Hart via EV]

EVDL Administrator wrote:

The autonomous onboard-PV EV is a sweet dream.  Who wouldn't love
to drive on pure sunshine and never have to fuel up or plug in?
But at the current state of the art, that's your heart talking, not
your head.


Ben Goren via EV wrote:

Not just current state of the art...it's never going to be practical
for the four-door five-passenger freeway sedan that dominates the
roadways; there just isn't enough insolation.


I agree for normal cars. But I have to wonder... what about railroad 
cars? Their rolling resistance is vastly lower, they have a huge roof 
area, and almost always sit in the sun. Could one make a commuter train 
or freight train with PV panels on the roof of every car. Would they 
collect enough power to be useful?


--
The ones who are crazy enough to think that they can change
the world, are the ones who do. -- Steve Jobs
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com
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Re: [EVDL] Light-weight 100W PV roof panel for 48V e-carts> ?Is it worth it?

[EVDL Administrator via EV]

On 22 Sep 2015 at 15:12, Robert Bruninga via EV wrote:

> People forget that battery systems are not only very inefficient ...

Doesn't that depend on how you use them?  For example, lead batteries are 
very close to 100% efficient between 0% and 80% SOC.  Virtually all of the 
energy goes into the charging reaction and almost none into heat.  

I suspect that other chemistries have similar SOC ranges over which they're 
similarly efficient.

> ... require maintenance ... 

Most modern batteries don't need the kind of maintenance required for lead, 
no?

> but whenever they are fully charged, then the solar panels are
> providing nothing in return for their investment. 

Oh, there I agree!  It's a major challenge and expense to provide enough 
capacity to store all the energy a big PV system harvests in a day, 
especially if you don't need it within the following 24 hours.  If you have 
nowhere to go in that dump-pack-charged EV, you're going to need a LOT of 
storage to hang on to the energy.

So that infinitely large battery, the grid, is great to have.  Trouble is, 
it's not free to use, and you (we) don't own it.  

Because most utilities are privately owned businesses, we the public have no 
fundamental right to access that big battery.  But business controls 
politics, and the laws that once controlled these regulated monopolies and 
granted us that right are rapidly being ground down.  The grid is apt to get 
a lot more expensive to use, if not unavailable, in the years ahead.  

So while I think you're right about the grid in the short term, I suspect 
that the long-term future for storing solar energy for your EV is in 
batteries -- LOTS of them.  The idea of using depreciated lithium EV 
batteries whose diminished capacity no longer serves for the EVs is really 
appealing, as long as it doesn't mean lowered efficiency.  (Reduce, reuse, 
recycle ...)

David Roden - Akron, Ohio, USA
EVDL Administrator

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Re: [EVDL] Light-weight 100W PV roof panel for 48V e-carts> ?Is it worth it?

[Robert Bruninga via EV]

Yes, but a grid-tied solar system does not need a "dump battery" so that
is a 100% wasted investment.  Just charge from the net-metereed solar
system as is.  Bob

-Original Message-
From: EV [mailto:ev-boun...@lists.evdl.org] On Behalf Of Cor van de Water
via EV
Sent: Tuesday, September 22, 2015 4:12 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Light-weight 100W PV roof panel for 48V e-carts> ?Is
it worth it?

Bob,
I think the comparison of dump pack versus roof mounted option was
comparing a house mounted solar+dump solution to a *car*roof mounted solar
panel, which is easy to beat in financial terms due to the cost of
flexible solar for car roof and the unreliable insolation on a car.
Other attempts at this have constructed car charging car ports to get
increased efficiency from solar panels other than on the car itself.

Cor van de Water
Chief Scientist
Proxim Wireless

office +1 408 383 7626  Skype: cor_van_de_water
XoIP   +31 87 784 1130  private: cvandewater.info
www.proxim.com



This email message (including any attachments) contains confidential and
proprietary information of Proxim Wireless Corporation.  If you received
this message in error, please delete it and notify the sender.  Any
unauthorized use, disclosure, distribution, or copying of any part of this
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-Original Message-
From: EV [mailto:ev-boun...@lists.evdl.org] On Behalf Of Robert Bruninga
via EV
Sent: Tuesday, September 22, 2015 12:13 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Light-weight 100W PV roof panel for 48V e-carts> ?Is
it worth it?

-Original Message-
>> That's 1% to 4%.  Better than most banks.  And FAR better for the
>> future since it displaces X amount of coal burning.

> I'll bet a cup of coffee that stationary panels going to a set of
batteries used as a dump pack for the golf cart would still financially
outperform the roof-mounted option.

When Can I collect the cup?

Only if the Golf Cart and dump-pack are FULLY discharged every day.
Because only then are you using the solar panels.  A solar panel just
sitting there in the sun connected to a fully charged battery is providing
ZERO return on investment.

That is why NET metering is the best economics hands down.  You get 100%
of the energy all the time, every day, no matter how much you use.

People forget that battery systems are not only very inefficient, require
maintenqance, but whenever they are fully charged, then the solar panels
are providing nothing in return for their investment.  And since battery
systems have to have oversized solar panels to make up for cloudy days,
then by definition, every fully sun day, then all the excess solar energy
beyond full charge is simply wasted.

My conclusion is that any use of batteries for storing solar energy wastes
$2 of every $3 invested in the solar system.  Grid-tie wastes none of it.
You get full retail value for every watt that falls on the panels no
matter where you use it.

Bob, WB4APR

You can use cheaper panels that get maximum insolation, and the only
concern for the dump pack is total lifetime cost per kWh in and out --
weight or volume or similar concerns are irrelevant.

A significant fraction of the electric vehicles on the road are already
solar powered; EV owners are statistically much more likely to have
rooftop solar generation than others. Except as a gimmick or an
engineering challenge or in unreal fringe cases (extraterrestrial
planetary exploration), carting the panels around with you is the most
over-the-top wasteful way to get to a "green" car. It's pure conspicuous
consumerism --which is perfectly fine if you can afford and appreciate the
luxury...just don't pretend that it's saving the planet or that it makes
good financial sense.

b&
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Re: [EVDL] Light-weight 100W PV roof panel for 48V e-carts> ?Is it worth it?

[EVDL Administrator via EV]

On 22 Sep 2015 at 19:35, Robert Bruninga via EV wrote:

> Yes, but a grid-tied solar system does not need a "dump battery" so that
> is a 100% wasted investment.  Just charge from the net-metereed solar
> system as is.

Barring an unlikely major change in America's political system that vastly 
reduces the influence of money on laws, grid tie is going to be effectively 
gone in a few years.  The utilities despise it, and will price it out of 
existence.

You may be lucky enough to be grandfathered for a while -- or maybe not.  
Most of us won't have that nearly-infinite, nearly-free battery that you 
have right now.  

We'd better be making other plans.

I'm sure there are huge practical barriers, but wouldn't it be great to 
develop democratically-controlled local or even regional consortia of RE 
users who pool their resources to build large storage facilities, and 
intertie their systems that way?  

While we're at it why not make them vehicle-sharing programs, too? You drive 
a small EV to work every day, but if you need an ICE van for the weekend, 
you can trade for a modest fee.

I know, now I'M the dreamer.  :-\

David Roden - Akron, Ohio, USA
EVDL Administrator

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Re: [EVDL] Light-weight 100W PV roof panel for 48V e-carts> ?Is it worth it?

[Robert Bruninga via EV]

Agreee.  Simply do the math for your application.  Then compare the value
of the charge to your cost.
Done.

Of course, everyone's value may be different.  I drive around with $2000
worth of solar panels (200W) on the roof of my EV, just to make it more
visibily obvious.   Gets the conversations going... The energy gained (15
cents) per day is trivial, but the conversations with unbelievers is
priceless.

Bob, WB4APR

-Original Message-
From: EV [mailto:ev-boun...@lists.evdl.org] On Behalf Of Jay Summet via EV
Sent: Tuesday, September 22, 2015 10:31 AM
To: ev@lists.evdl.org
Subject: Re: [EVDL] Light-weight 100W PV roof panel for 48V e-carts> ?Is
it worth it?



On 09/22/2015 09:19 AM, EVDL Administrator via EV wrote:
> On 22 Sep 2015 at 3:50, brucedp5 via EV wrote:
>
>> ? Is this a useful product worthy of the co$t, or is it a profitable
>> feel-good add-on for bragging-rights ?

> What it MIGHT do that's potentially at least as useful -- IF you park
> mostly in the sun --- is dribble a little charge back into the battery
> when the car isn't being driven.  That'll improve battery cycle life a
> bit.  Calculating whether the resulting battery cost savings will
> offset the cost of the PV panel will be left as an exercise for the
> reader. ;-)

On the other hand, if you only use your golf cart lightly only on the
weekends, it may be able to recharge it the rest of the week.

Jay
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Re: [EVDL] Light-weight 100W PV roof panel for 48V e-carts> ?Is it worth it?

[Peri Hartman via EV]

I think it depends on why you want it.  If you are altruistic and want 
to cut your grid usage, then it helps.  If you think you'll get more 
range out of a charge, then apply David's calculations to the amount of 
Wh you'll get while on the course.  Probably just a few percent more 
range.


Peri

-- Original Message --
From: "EVDL Administrator via EV" <ev@lists.evdl.org>
To: "Electric Vehicle Discussion List" <ev@lists.evdl.org>
Sent: 22-Sep-15 6:19:43 AM
Subject: Re: [EVDL] Light-weight 100W PV roof panel for 48V e-carts> ?Is 
it worth it?



On 22 Sep 2015 at 3:50, brucedp5 via EV wrote:


 ? Is this a useful product worthy of the co$t, or is it a profitable
 feel-good add-on for bragging-rights ?


Much of the answer is right in the story:

 As a yearly average, the system generates 29 percent of the total 
energy
 required to drive eight miles per day in West Palm Beach, Fla. That 
reduces
 the energy needed to recharge the battery by 29 percent. Results may 
vary

 depending on area and usage.

 By continually transferring energy to the batteries, the panels limit 
how deep

 into the battery reserve a vehicle must go during a typical use.


I suspect this is a best-case estimate.  Let's run some numbers.

First let me warn you that there's a fair bit of hand-waving here.  I'm 
not

an expert in these matters.  If you're a PV expert and can come up with
better numbers than mine, by all means please do so.

IIRC a typical golf car range is around 40-50 miles.  Using standard 
T105
type batteries this amounts to an energy usage of between 126 and 158 
Wh/mi.

Let's call it 150 Wh/mi for convenience.

Driving 8 miles per day will require 1200 WH per day or (1200 * 365) ==
438000 Wh/year if you drive the car every day (as the PR release seems 
to

suggest).

This panel can produce 100 watts, but if that's a typical rating it'll 
only
apply when the golf car is parked in the sun with the sun directly 
overhead.
At other times the output will be lower, but I'm not a solar expert so 
I
don't know by how much.  I'll take a wild guess and estimate that the 
panel
will average 30 watts over an average day's sunshine (including dawn 
and

dusk).  Someone please correct me if that's too far off.

So that's 30W * 12h == 360 Wh/day * 234 days (average sunny days per 
year in
West Palm Beach) == 84240 Wh/year.  This is 19% of the energy required 
to

drive 8 miles per day, about a third less than Club Car claim, but
surprisingly close.

But even my 19% estimate assumes the golf car will be in the sun any 
time

the sun is shining.  If you park it in a garage, or in the shade of a
building or tree, it gains little or nothing.  How many people 
deliberately

park their cars (golf or otherwise) in the sun on a hot summer day in
Florida?

Other factors will affect solar gain.  For example, if you drive it on 
a
tree lined street, or a city street with tall buildings around it, it 
will

gain less solar energy.

So, is this just a "feel-good add-on"?  Well ... as with any other 
vehicle
option, how much a given user gains from this one depends on where and 
how
she drives.  But for most users, I'd say it'll probably yield more 
bragging

rights than range.

What it MIGHT do that's potentially at least as useful -- IF you park 
mostly
in the sun --- is dribble a little charge back into the battery when 
the car
isn't being driven.  That'll improve battery cycle life a bit.  
Calculating
whether the resulting battery cost savings will offset the cost of the 
PV

panel will be left as an exercise for the reader. ;-)

FWIW, in looking for info on this I ran across several dealers offering
aftermarket PV panel options for golf cars.  One claimed a (peak) 
output of

220 watts.  The price was $1450.

Is it worth it?  I see 12v 50w generic PV panels on Ebay for around 
$100

each.  Five of them would give you peak 250W into a charge controller.
Speaking of which, I see 48v, 30-45 amp charge controllers on Ebay at
prices from $160 to $260.

The dealer I mentioned above also provide a roof frame and struts.  
What do
you think that's worth, maybe $150?   So they're making around $700 on 
each

kit.  That's a 100% return on the parts cost.  Not too shabby.

David Roden - Akron, Ohio, USA
EVDL Administrator

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[EVDL] Light-weight 100W PV roof panel for 48V e-carts> ?Is it worth it?

[brucedp5 via EV]

? Is this a useful product worthy of the co$t, or is it a profitable
feel-good add-on for bragging-rights ?

http://americancityandcounty.com/green/panels-deliver-solar-power-vehicle-lineup-related-video
Panels deliver solar power in vehicle lineup (with related video)
Sep 21, 2015

[image  
http://americancityandcounty.com/site-files/americancityandcounty.com/files/imagecache/large_img/uploads/2015/09/clubcarsolardriveprecedentfoverheadlgjpg.jpeg
]

The panels reduce emissions, cut charging costs and increase range on
several Club Car vehicle models. They also reduce the need for
grid-generated energy.

The firm’s 100-watt Solar Drive Charging Panel Assembly enables owners of
48-volt electric Club Car Precedent golf cars, Carryall utility vehicles and
Villager low-speed vehicle (LSVs) to capture, store and use solar power. The
panels are suited for the Augusta, Ga.-based Club Car’s golf, consumer and
commercial models.

As a yearly average, the system generates 29 percent of the total energy
required to drive eight miles per day in West Palm Beach, Fla. That reduces
the energy needed to recharge the battery by 29 percent. Results may vary
depending on area and usage. 

By continually transferring energy to the batteries, the panels limit how
deep into the battery reserve a vehicle must go during a typical use.

The panels are based on technology developed for the U.S. Marine Corps,
which uses it to run communications equipment in the Middle East. The panels
are made in the U.S. of a lightweight, impact-resistant, photo-voltaic
material with a Teflon-like coating that protects the cells.

Measuring 40 by 26 inches, the panels fit snuggly on the canopies or cabs of
Club Car vehicles. They weigh less than six pounds and are just 0.20 inches
thick.

Traditional solar panels are made in China, framed in tempered glass and
weigh approximately 24 pounds, creating drag on the vehicle and limiting the
benefits. What’s more, service and warranty issues can be a big problem with
panels made abroad, according to the company.

The panels are designed with power-harvesting technology that optimizes
solar power during various weather conditions and rapidly converts it into
electricity to recharge the batteries and power vehicles. The system also
features an intelligent microprocessor that allows a high rate of charge and
reduces charge time, without overheating.

The panels come complete with a controller, connector to the vehicle’s power
supply, all necessary hardware and installation instructions. They can be
user- or dealer-installed in about 20 minutes.

In addition to the standard 100-watt panel for the above-mentioned vehicles,
Club Car can configure solar panels for other types of vehicles through its
Custom Solutions Department.

Club Car vehicles and accessories are sold through Authorized Club Car
Dealers [
http://www.clubcardealer.com/
].
[© americancityandcounty.com]




For EVLN posts use:
http://evdl.org/evln/


{brucedp.150m.com}

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Re: [EVDL] Light-weight 100W PV roof panel for 48V e-carts> ?Is it worth it?

[Jay Summet via EV]

On 09/22/2015 09:19 AM, EVDL Administrator via EV wrote:

On 22 Sep 2015 at 3:50, brucedp5 via EV wrote:


? Is this a useful product worthy of the co$t, or is it a profitable
feel-good add-on for bragging-rights ?



What it MIGHT do that's potentially at least as useful -- IF you park mostly
in the sun --- is dribble a little charge back into the battery when the car
isn't being driven.  That'll improve battery cycle life a bit.  Calculating
whether the resulting battery cost savings will offset the cost of the PV
panel will be left as an exercise for the reader. ;-)


On the other hand, if you only use your golf cart lightly only on the 
weekends, it may be able to recharge it the rest of the week.


Jay
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Re: [EVDL] Light-weight 100W PV roof panel for 48V e-carts> ?Is it worth it?

[EVDL Administrator via EV]

On 22 Sep 2015 at 3:50, brucedp5 via EV wrote:

> ? Is this a useful product worthy of the co$t, or is it a profitable
> feel-good add-on for bragging-rights ? 

Much of the answer is right in the story:

> As a yearly average, the system generates 29 percent of the total energy
> required to drive eight miles per day in West Palm Beach, Fla. That reduces
> the energy needed to recharge the battery by 29 percent. Results may vary
> depending on area and usage. 
> 
> By continually transferring energy to the batteries, the panels limit how deep
> into the battery reserve a vehicle must go during a typical use.

I suspect this is a best-case estimate.  Let's run some numbers.

First let me warn you that there's a fair bit of hand-waving here.  I'm not 
an expert in these matters.  If you're a PV expert and can come up with 
better numbers than mine, by all means please do so.

IIRC a typical golf car range is around 40-50 miles.  Using standard T105 
type batteries this amounts to an energy usage of between 126 and 158 Wh/mi.
Let's call it 150 Wh/mi for convenience.  

Driving 8 miles per day will require 1200 WH per day or (1200 * 365) == 
438000 Wh/year if you drive the car every day (as the PR release seems to 
suggest).

This panel can produce 100 watts, but if that's a typical rating it'll only 
apply when the golf car is parked in the sun with the sun directly overhead. 
At other times the output will be lower, but I'm not a solar expert so I 
don't know by how much.  I'll take a wild guess and estimate that the panel 
will average 30 watts over an average day's sunshine (including dawn and 
dusk).  Someone please correct me if that's too far off.

So that's 30W * 12h == 360 Wh/day * 234 days (average sunny days per year in 
West Palm Beach) == 84240 Wh/year.  This is 19% of the energy required to 
drive 8 miles per day, about a third less than Club Car claim, but 
surprisingly close.

But even my 19% estimate assumes the golf car will be in the sun any time 
the sun is shining.  If you park it in a garage, or in the shade of a 
building or tree, it gains little or nothing.  How many people deliberately 
park their cars (golf or otherwise) in the sun on a hot summer day in 
Florida?

Other factors will affect solar gain.  For example, if you drive it on a 
tree lined street, or a city street with tall buildings around it, it will 
gain less solar energy.  

So, is this just a "feel-good add-on"?  Well ... as with any other vehicle 
option, how much a given user gains from this one depends on where and how 
she drives.  But for most users, I'd say it'll probably yield more bragging 
rights than range.

What it MIGHT do that's potentially at least as useful -- IF you park mostly 
in the sun --- is dribble a little charge back into the battery when the car 
isn't being driven.  That'll improve battery cycle life a bit.  Calculating 
whether the resulting battery cost savings will offset the cost of the PV 
panel will be left as an exercise for the reader. ;-)

FWIW, in looking for info on this I ran across several dealers offering 
aftermarket PV panel options for golf cars.  One claimed a (peak) output of 
220 watts.  The price was $1450.  

Is it worth it?  I see 12v 50w generic PV panels on Ebay for around $100 
each.  Five of them would give you peak 250W into a charge controller.  
Speaking of which, I see 48v, 30-45 amp charge controllers on Ebay at  
prices from $160 to $260.  

The dealer I mentioned above also provide a roof frame and struts.  What do 
you think that's worth, maybe $150?   So they're making around $700 on each 
kit.  That's a 100% return on the parts cost.  Not too shabby.  

David Roden - Akron, Ohio, USA
EVDL Administrator

= = = = = = = = = = = = = = = = = = = = = = = = = = = = =
EVDL Information: http://www.evdl.org/help/
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = 
Note: mail sent to "evpost" and "etpost" addresses will not 
reach me.  To send a private message, please obtain my 
email address from the webpage http://www.evdl.org/help/ .
= = = = = = = = = = = = = = = = = = = = = = = = = = = = =


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