[aprssig] Tesla Field Day mode (or any EV/Hybrid) at work

[Rick Green]

On Thu, 28 Feb 2019, Jason KG4WSV wrote:

> 
> 
> On Thu, Feb 28, 2019 at 8:47 AM Robert Bruninga <bruninga at usna.edu> wrote:
>
>        If just one of those spots is covered with 12 solar panels, that is enough to provide free transportation 40 miles a day) forever.
> 
> If a solar footprint that size could actually provide a useful amount of power to the vehicle, why the heck would you put it on the GROUND and not on the VEHICLE???
>
   'That Size' is approximately 96 square feet, or 6 feet by 16 feet, 
approximately the entire footprint of a passenger car. How many vehicles could 
you sell with the boxy shape it would take to have 96 square feet of essentially 
flat roof?
   Installing solar cells directly on a vehicle would also be wastefully 
inefficient, as they would not be optimally oriented to the sun, and once the 
onboard batteries were fully charged, any energy captured could not be utilized 
unless the car were connected to an external load.  These inefficiencies would 
have the effect of increasing the 'payback time' for the system, and considering 
the cost of funds and the short lifespan of the typical passenger car, payback 
may be never.
   Solar panels installed as a 'carport shelter' over existing parking lots is 
already being implemented.   Fixed installations may be grid-tied or have other 
fixed 'dump loads' to utilize the excess power generated, and will certainly 
outlive the vehicles they are charging on day one.
   The local Chevy dealer installed just such an array over their car lot when 
the Volt was introduced. I'm assuming that was mostly considered an advertising 
promotional expense, but in my travels, I've observed similar installations on a 
larger scale at Michigan State University, and also along I-10 in Tucson, AZ. 
If the technology is economically viable in those disparate places, it's 
probably viable everywhere.
   Providing Grid power for charging at worksites during the peak demand 
afternoons would further exacerbate that problem.  Providing Grid-tied Solar at 
daytime worksites would benefit the employees, the employer's business, and the 
community at large.

...and as for Field Day itself, is there an inverter on the market today which 
will accept the high voltage DC input of today's hybrids and EVs, and will also 
self-start without a grid-tie clock source?  In the ~10Kw range?  With US 
standard 240VAC Split-phase output?  That's my estimate of what it would take to 
run a 5 transmitter club FD operation comfortably...  The Tesla's battery pack 
is about 75 KwH, right? Or about 3 Kw average load for a 24 hour FD operation, 
so I'm guessing a 10Kw inverter would handle the peaks.

-- 
Rick Green N8BJX

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