Again, Solar Thermal is dead,dead,dead according to almost all articles I
have seen.

Solar thermal hot water heating is about 75% efficient but ONLY IF 100% of
that heat is used.

Solar PV is only 15% “efficient” but is now at least FIVE TIMES CHEAPER
than a solar water heater for the same square foot of panel.  Bingo that
makes them EQUAL as far as investment is concerned.

My point with the Grid-tie is that you get full retail value for every
“convertible” photon that hits your array no matter whether it is heating
hot water, or once the water is hot, then it goes to the net meter and you
still get full retail value for it.

Plus, even disregarding the 5 times cheaper solar panel than thermal hot
water heating system, and pumps and motors and maintenance, you still get a
TRIPLE in efficiency when the 15% PV panel drives a 300% efficient heatpump
water heater.  So even apples to apples, the 15% is now reaqlly equal to
45% relative to heating water.  But five or more times cheaper and
maintenance free.

The point is with solar thermal, that every SUNY day when the sun has fully
heated the tank by say 1 PM, then the rest of the solar day is producing
ZERO return on ivesment.

Whereas with PV, the extra solar on a sunny day is being banked in your
net-meter at full retail value for use later…

I ikonw this is off-topic for the EV list, but making sure everyone
understands the value of heatpump technology will help with Car heating too.

Hope that clarifies.


*From:* ROBERT []
*Sent:* Wednesday, November 29, 2017 5:01 PM
*To:* Robert Bruninga;
*Subject:* Re: [EVDL] Heat pump vs resistive Heater (OT, but somewhat EV

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 <>
*Sent:* Wednesday, November 29, 2017 1:17 PM
*Subject:* RE: [EVDL] Heat pump vs resistive Heater (OT, but somewhat EV

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

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.


*From:* ROBERT []
*Sent:* Wednesday, November 29, 2017 2:49 PM
*To:* Robert Bruninga
*Subject:* Re: [EVDL] Heat pump vs resistive Heater (OT, but somewhat EV

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 understand
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 <>
*Sent:* Wednesday, November 29, 2017 10:05 AM
*To:* Electric Vehicle Discussion List
*Subject:* RE: [EVDL] Heat pump vs resistive Heater (OT, but somewhat EV

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

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.

-----Original Message-----
From: EV [ <>] On
Behalf Of ROBERT via EV
Sent: Wednesday, November 29, 2017 12:05 AM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Heat pump vs resistive Heater (OT, but somewhat EV

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 <> on behalf of John Lussmyer via EV
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

On Tue Nov 28 20:11:48 PST 2017 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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