m: EV On Behalf Of Jan Steinman via EV
Sent: Thursday, July 18, 2019 5:28 PM
To: ev@lists.evdl.org
Cc: Jan Steinman
Subject: Re: [EVDL] Solar off grid with an EV? (DC AC/heatpumps and
waterheating)
> From: Lee Hart It's like the "ICE" solution
> wins. When you treat oil supplie
Original Message --
> From: "Robert Bruninga via EV" mailto:ev@lists.evdl.org >
> To: "Electric Vehicle Discussion List" mailto:ev@lists.evdl.org >
> Cc: "Robert Bruninga" mailto:bruni...@usna.edu >
> Sent: 18
> From: Lee Hart
> It's like the "ICE" solution wins. When you treat oil supplies as
> "limitless", then extremely inefficient ICEs are the popular choice,
> because it's cheaper.
Thanks for that, Lee.
I don't have numbers for a full-on "EMERGY" analysis of the two, and have no
desire to get
-
From: EV On Behalf Of Peri Hartman via EV
Sent: Thursday, July 18, 2019 5:04 PM
To: Electric Vehicle Discussion List
Cc: Peri Hartman
Subject: Re: [EVDL] Solar off grid with an EV? (DC AC/heatpumps and
waterheating)
(Really off topic, here) I'm curious about the overall efficiency of heat
pump
ect: Re: [EVDL] Solar off grid with an EV? (DC AC/heatpumps and
waterheating)
*-Because a heat pump system is using energy to "move" existing heat,
it gives you 400% (or more!) efficiencies. [i.e. you use 800 watts to
drive a compressor and fans, but get 3,200 watts of heat into
> *-Because a heat pump system is using energy to "move" existing heat,
> it gives you 400% (or more!) efficiencies. [i.e. you use 800 watts to
> drive a compressor and fans, but get 3,200 watts of heat into the
> tank, while cooling the area around the water heater.]
I think it is more like 3 to
Just some nitpics...
>> Is solar thermal water heating *still* more efficient?
> Suppose you have a limited roof area that can only collect 1 KWH of
energy.
> PV cells might convert that into 150 watts of electricity. A solar
water heat
> might convert it into 300 watts of heat in your water
No energy source is free. The cost is in extracting it and efficiency has a
very narrow definition in engineering and does not include cost.
Sent from my iPhone
> On Jul 18, 2019, at 10:33 AM, Lee Hart via EV wrote:
>
> Mark Abramowitz via EV wrote:
>> Is solar thermal water heating *still*
Mark Abramowitz via EV wrote:
Is solar thermal water heating *still* more efficient?
"Efficient" has a different meaning when your energy source is free.
Energy efficiency usually means getting the most good out of a finite
source of energy.
Suppose you have a limited roof area that can
On 7/18/19 7:43 AM, Willie via EV wrote:
On 7/18/19 6:33 AM, Jay Summet via EV wrote:
*-Because a heat pump system is using energy to "move" existing heat,
it gives you 400% (or more!) efficiencies. [i.e. you use 800 watts to
drive a compressor and fans, but get 3,200 watts of heat into
On 7/18/19 6:33 AM, Jay Summet via EV wrote:
*-Because a heat pump system is using energy to "move" existing heat, it
gives you 400% (or more!) efficiencies. [i.e. you use 800 watts to drive
a compressor and fans, but get 3,200 watts of heat into the tank, while
cooling the area around the
On 7/18/19 12:01 AM, Mark Abramowitz via EV wrote:
Is solar thermal water heating *still* more efficient?
With a perfect system, solar thermal is probably still more efficient
from a "space on your roof" perspective. [a "square feet of solar
collectors needed to heat the water".] (I'm
On 7/17/19 10:04 PM, Robert Bruninga via EV wrote:
Where are you getting 25 cents a watt panels? Must be some real junk
sunelec.com sells them by the truck load, or pallet from Miami.
Currently the 25 cents a watt are for 325W (72 cell panels). Minimum
quantity is about 25 on a pallet and
er you do not use, then you still get full 100% retail value for your
> solar energy. Whereas with thermal solar, unless you use 100% of your hot
> water every single day, then your thermal panels are doing nothing once the
> tank is hot.
>
> Bob
> -Original Message-
>
Thanks for the agreement. When I first read your paragraph, there was a
smudge on my screen and I read this line as:
"There is of course where to put the wire "
I read as "There is of course where to put the wife.".
so true!
Bob
On Wed, Jul 17, 2019 at 10:09 PM Michael Ross via EV
wrote:
>
> Where are you getting 25 cents a watt panels? Must be some real junk
sunelec.com sells them by the truck load, or pallet from Miami.
Currently the 25 cents a watt are for 325W (72 cell panels). Minimum
quantity is about 25 on a pallet and last time I bought some from there, I
think my two
Where are you getting 25 cents a watt panels? Must be some real junk.
On 7/17/2019 2:28 PM, Robert Bruninga via EV wrote:
Inefficent yes, but hooking up 2 wires is a lot easier than building one out
of copper, plywood, glass and paint. With solar panels costing only 25
cents per watt (on a
There was a time when solar thermal and its 70% efficiency made sense,
because PV cost too much. But that time has passed.
I think that PV is now better than solar thermal. There are a lot of hidden
costs and difficulties putting a thermal collector on one's roof. There is
a bunch of piping that
On Behalf Of Jan Steinman via EV
Subject: Re: [EVDL] Solar off grid with an EV? (DC AC/heatpumps and
waterheating)
> From: Robert Bruninga
>
> … using about 4 Solar panels
> for the bottom coil in a water heater are a good idea. You need hot
> water every day, and so this gives you 100
> From: Robert Bruninga
>
> … using about 4 Solar panels
> for the bottom coil in a water heater are a good idea. You need hot water
> every day, and so this gives you 100% effectiveness of these 4 or so
> panels.
Seems like a horribly inefficient way of heating water!
Direct solar hot water
These days, most new Air conditioners are variable speed for maximum
efficiency. This means they rectify line voltage to DC and then run
everything internally off of DC. This means you can run them on high
voltage DC just as well as AC. Some manufacturers even advertise them that
way. You can
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