My point was solar hot water collectors do work if the system is designed 
correctly.  A solar hot water collector is 80 -90% efficient where as a PV 
panel is 15-18% at best.  My solar hot water system is a combined hot water 
system and radiant floor heating system.  It works.  A PV system for heating 
would need a large battery backup system to work at night.  A hot concrete slab 
retains the heats for 5 - 6 hrs at night.  The biggest consumers of energy in a 
house are HVAC, Hot Water Heater, Ovens, and Clothes Dryers.  A solar hot water 
system can reduce home heating cost and hot water cost with much higher 
efficiency than a PV system.  In my opinion, a combination PV and hot water 
collector system would be the best.


Your statement "You get full retial value from every photon of sun whether you 
are heating water or using it for other!" is not correct.  For every photon of 
energy that falls on a PV panel, over 85% is not converted to electrical 
energy.  PV panels are not efficient converters of light energy to electricity. 
 Before everyone howls at me.  Fossil fuel conversion to electrical energy is 
not super efficient either.


I don't think Lowes has a hybrid hot water heater for $699.00.  Lowes sales the 
AO Smith brand of hot water heaters.  Their hybrid unit is a good unit with an 
energy rating of approximately $119 per year but with a 9 year tank warranty.  
The cost is about $1500.00.





________________________________
From: Robert Bruninga <bruni...@usna.edu>
Sent: Wednesday, November 29, 2017 1:17 PM
To: ROBERT
Subject: RE: [EVDL] Heat pump vs resistive Heater (OT, but somewhat EV related)


Your email was hard to read since there 2were no paragraphs, but I get the gyst.



I agree, Thermal solar hot wter heating is dead,dead,dead since about 2005.  
And even then was usless on the family cycle since all therm gain after the 
tank is hot is wasted.



Solar PV grid-tied with a heatpump water heater is the only way to go.  You get 
full retial value from every photon of sun whether you are heating water or 
using it for other!



P.S.  I just looked and Lowes has 50 gal htepupp water heaters for $699.  Wow.

Bob





From: ROBERT [mailto:bhensle...@msn.com<mailto:bhensle...@msn.com>]
Sent: Wednesday, November 29, 2017 2:49 PM
To: Robert Bruninga
Subject: Re: [EVDL] Heat pump vs resistive Heater (OT, but somewhat EV related)



Robert, I have a similar arrangement with my solar hot water system and hybrid 
hot water heater.  The solar collectors via a water to water heater exchanger 
heats the water in a preheat tank and the water goes to the hybrid hot water 
heater before going to the fixtures.  The preheat tank is a 50 gal standard 
propane hot water heater.  The system is very efficient.  The high efficiency 
is due to system design and lifestyle.  The efficiency by system design is 
obvious.  The efficiency by lifestyle is the interesting part.  Most people use 
hot water in the morning and in the evening.  People get up before the sun 
rises and hit the hot water heavily.  In a system with a standard electric hot 
water heater, before the solar collectors can heat the hot water (sun has not 
come up), the water heater resistance elements reheat the water.  You get no 
gain form the solar system.  The family goes off to work and school.  The sun 
comes up.  The solar collectors maintain the temperature of the hot 
 water during the day.  The family returns home and start hitting the hot 
water.  Again with a standard hot water heater and after sunset, the water 
heater resistance elements reheat the water.  Again no gain from the solar 
system.  This lifestyle is the reason most people are disappointed in a hot 
water solar system.  They see very little energy use decrease because the solar 
is only effective during the day maintaining the heat loss from the hot water 
heaters.  The solar/hybrid system works better.  I keep the hybrid unit in heat 
pump mode only.  This is the most efficient setting.  We get up in the morning 
with 100 gals of hot water.  We hit the hot water heavily.  The hybrid unit 
starts heating the water at a very slow recovery rate and very efficiently.  
The water does not get fully reheated before the sun rises.  The solar heat 
finishes reheating the water and the hybrid unit is shut off (hybrid unit has 
this type of control).  Note: the pump draws water from the bottom of both
  heaters and circulates through the heat exchanges ... very important design 
feature.  The solar system heats the water to 150 F (hybrid unit set point is 
120 F) in both hot water heaters during the day.  Come evening, I have 100 gals 
of 150 F water to wash dishes take showers etc.  The hybrid unit is turned back 
on for the night.  Usually around 12:00 - 1:00 am the hybrid unit will need to 
run to maintain the 120 F water in the hybrid unit.  Typically it takes 1KWHr 
during the night.  Depending on the amount of hot water usage in the morning 
the hybrid unit uses 1 - 2 KWHr of electricity per day.  In the summer, the 
usage is 0.  During Jan - Feb the usage has been as high as 50 KWHr per month.  
The yearly cost is $50 - $80 per year for electricity for the hybrid unit at 
0.15 KWHr.  I tell this story because so many people tell me they installed a 
solar hot water system and it did not help.  They are correct because the local 
solar companies and most national companies do not unders
 tand lifestyle and its effect on energy efficiency.  Another point is a hybrid 
unit cost $1500 - $1800.  The $1800 unit has a stainless steel tank with a 20 
year warranty.  A standard electric hot water heater cost $400 - $450 with a 9 
year tank warranty.  I will let you do the math but considering it takes 2 
standard units over a 20 year period and the energy saving from a hybrid unit, 
only a short sighted person would buy a standard hot water heater with or 
without solar.  Also, I got by two hybrid units off craigslist for $100 each.  
They both work.  I only needed to clean the elements and replace on element.  
But that is another story.





________________________________

From: Robert Bruninga <bruni...@usna.edu<mailto:bruni...@usna.edu>>
Sent: Wednesday, November 29, 2017 10:05 AM
To: Electric Vehicle Discussion List
Cc: ROBERT
Subject: RE: [EVDL] Heat pump vs resistive Heater (OT, but somewhat EV related)



AMEN!
When I installed my heatpump wter heater, I kept the old one.  Put them in
series so that the heatpump first heats the 50F incoming city water to
about 100F (intentionally set that low so that the heatpumps is  operating
most efficiently).  Then that water goes into the old electic tank where
the top coil is set to 110F.
So most of the heating is at the very high efficiency of the heatpump
unit.

Wrapped them both in 4" insulation.

And by only setting a final temp of 110F, the wife can still take a HOT
shower, though she is burning through 90% hot water and 10% cold to get
the right temp.  We can do this at this low temperature because of the 100
gallons of hot water available.

Bob
-----Original Message-----
From: EV [mailto:ev-boun...@lists.evdl.org] On Behalf Of ROBERT via EV
Sent: Wednesday, November 29, 2017 12:05 AM
To: Electric Vehicle Discussion List
Cc: ROBERT
Subject: Re: [EVDL] Heat pump vs resistive Heater (OT, but somewhat EV
related)

You guys are correct about a heat pump being more energy efficiency than a
resistance heating element.  I recently installed a hybrid hot water
heater.  I have an external energy monitor on this circuit.  The hybrid
hot water heater used 1/4 the energy of a standard hot water heater.  With
the tax credit, the heater will pay for itself in 4 years.


________________________________
From: EV <ev-boun...@lists.evdl.org<mailto:ev-boun...@lists.evdl.org>> on 
behalf of John Lussmyer via EV
<ev@lists.evdl.org<mailto:ev@lists.evdl.org>>
Sent: Tuesday, November 28, 2017 9:17 PM
To: Electric Vehicle Discussion List
Cc: John Lussmyer
Subject: Re: [EVDL] Heat pump vs resistive Heater (OT, but somewhat EV
related)

On Tue Nov 28 20:11:48 PST 2017 ev@lists.evdl.org<mailto:ev@lists.evdl.org> 
said:
>Heat can't magically be obtained from cold air.
>
>As the temperature drops, the pump must do a lot more work for an ever
>smaller amount of heat.

The one I just had put in the cabin is better than an electric heater down
to around 0 deg F.
Around here, dropping below freezing is rare event.

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