Super Simple Solar Energy

[amdx]

On 11/2/2019 5:28 PM, John S wrote:

On 11/2/2019 4:49 PM, amdx wrote:
On 11/2/2019 2:33 PM, whit3rd wrote:
On Saturday, November 2, 2019 at 12:03:47 AM UTC-7, Martin Riddle wrote:

On Fri, 1 Nov 2019 13:19:32 -0700 (PDT), "dcaster@krl.org"
dcaster@krl.org> wrote:

... Seems like a good project,...t to provide a little heat to the
basement.  So it would just be solar panels connected to a
resistive load.


Hot water solar collectors are the most efficient out of all solar
things. Most bang for the buck too. They move more heat than PV'S
could.

Absolutely, if you want area heat, solar HEATING of water for pumped
circulation
to the basement is a good idea.   It's as effective as a south-facing
basement
window...  except you can turn it off in the summer.  Mirror area is
cheaper
than solar-panel area, and there's black vacuum-insulated glass tubes
that
are wonderfully effective at heating a water-based fluid (you want
some antifreeze).

For my basement, though, i'm  more concerned with moisture; it has a
resident
dehumidifier.


Why not just heat the air and move it where you want it.
Assuming that won't be far.
                      Mikek

Heating the air does not remove the moisture. The water content in the
air stays constant, just the *relative* humidity goes down. To remove
the moisture you must cool the air to below the dew point. You can then
heat the air if needed.

That may be true, but neither does resistance heating or hot water
heating.
So, if is is physically possible to place the solar air collectors on
the South side near his basement, that will probably be the cheapest way
to go. Then if needed, he can get a dehumidifier.

> https://www.builditsolar.com/Projects/SpaceHeating/Space_Heating.htm

Hundreds of solar projects here.

Mikek

 

[dcaster@krl.org]

On Sunday, November 3, 2019 at 8:58:33 AM UTC-5, amdx wrote:

On 11/2/2019 5:28 PM, John S wrote:
On 11/2/2019 4:49 PM, amdx wrote:
On 11/2/2019 2:33 PM, whit3rd wrote:
On Saturday, November 2, 2019 at 12:03:47 AM UTC-7, Martin Riddle wrote:

On Fri, 1 Nov 2019 13:19:32 -0700 (PDT), "dcaster@krl.org"
dcaster@krl.org> wrote:

... Seems like a good project,...t to provide a little heat to the
basement.  So it would just be solar panels connected to a
resistive load.


Hot water solar collectors are the most efficient out of all solar
things. Most bang for the buck too. They move more heat than PV'S
could.

Absolutely, if you want area heat, solar HEATING of water for pumped
circulation
to the basement is a good idea.   It's as effective as a south-facing
basement
window...  except you can turn it off in the summer.  Mirror area is
cheaper
than solar-panel area, and there's black vacuum-insulated glass tubes
that
are wonderfully effective at heating a water-based fluid (you want
some antifreeze).

For my basement, though, i'm  more concerned with moisture; it has a
resident
dehumidifier.


Why not just heat the air and move it where you want it.
Assuming that won't be far.
                      Mikek

Heating the air does not remove the moisture. The water content in the
air stays constant, just the *relative* humidity goes down. To remove
the moisture you must cool the air to below the dew point. You can then
heat the air if needed.

That may be true, but neither does resistance heating or hot water
heating.
So, if is is physically possible to place the solar air collectors on
the South side near his basement, that will probably be the cheapest way
to go. Then if needed, he can get a dehumidifier.

https://www.builditsolar.com/Projects/SpaceHeating/Space_Heating.htm

Hundreds of solar projects here.

Mikek

Actually on the ground on the west side of the house near the basement. Not visible from inside the house. I already have a dehumidifier.

Dan

 

[Carl]

"Rick C" wrote in message
news:ddaaf2fa-05ed-4526-8b63-2ff459ec9497@googlegroups.com...

I'd rather bang out a little code on an MCU or FPGA than construct a frame
for some solar cells. I think that is the part of the system that will
need significant attention and effort. So rather than design and construct
the array myself, I'd save on the money for the electronics by building
that myself and buy the solar panel.

Just my opinion.

As I posted before, a commercial controller is available just for this at
www.techluck.com. He's a bit skimpy on details but my understanding is that
so long as the heater element resistance is low enough to always be able to
drag the PV array output voltage down below the point of maximum power
output his scheme will work. He apparently connects and disconnects the
heater with a big IGBT using PWM at a reasonably high frequency to control
the average current which in turn sets the output voltage for the available
sunlight at that instant to maximize the power output. He mentions 200 Hz,
and I assume that he has a capacitor across the panel output to limit
voltage sag during the on periods as Win suggested. He has a lot of good
practical info there, including the fact that using DC through the
thermostat contacts on a typical electric water heater will rapidly burn up
the contacts so simply connecting panels to the water heater won't work for
long, besides being very inefficient. If nothing else you can learn from
his testing with various panel voltages and heater power ratings.

--
Regards,
Carl Ijames

 

[Winfield Hill]

Rick C wrote...

On Saturday, November 2, 2019 at 8:14:34 PM UTC-4, Winfield Hill wrote:
Rick C wrote...

Your choice of trip voltages will pretty much keep operation
on the constant current portion of the curve. That will
certainly work a lot better than a simple fixed resistance
directly tied to the solar cells, but it does give up a
significant portion of the available power.
=20
I discovered that doing experiments in sunlight, comparing
different possibilities, can be a frustrating experience.
That's because the solar radiation is constantly changing.
10 or 20% changes due to a little haze, etc., are seen by
the instruments, even though the sky looks clear. Add a
few little puffy clouds, forget it. I came to realize that
eking out every last 10% was an exercise in futility, and
simplifying the electronics instead was a reasonable goal.

I don't understand your point. Eking out the last 10 or 20% is
exactly what a MPPT does for you. In this case it is even easier
since you are only trying to make heat. You don't even need a
regular MPPT converter. You just need a MPPT load. The required
circuit couldn't be much simpler. Switchers make noise and your
design is suboptimal because it leaves power in the solar array.
A linear MPPT load would not make significant electrical noise,
use very few parts and be very easy to design and build.

PWM is a super-simple way to turn a fixed load resistor into a
variable resistor, but I agree that a linear regulator would be
fine, because the lost heat in the big heat sinks would be part
of the air-heating purpose.

But I don't agree that one can count on eking out the last 10%
with MPPT. Before settling on my simple scheme, I purchased
eval boards for five different MPPT chips. My experiences with
them soured me on the concept of getting the last 5, 10 or 15%,
over the wide range of solar conditions one encounters. I'd say
probably the only way to succeed in that is to be creative with
hardware, and to write some refined software to control it. I
do hope the MPPT code in my roof's micro-inverters does that.

But even MPPT that misses perfection by 10% is awesome, because
with poor MPPT, or none at all, we will suffer up to 90% losses.

As for my other claim, that the sky's variability is so great,
that it's not even worth trying for the last 10%, look at plots
of 9 successive days of detailed data from my roof. Even the
best days suffered dips, and as for the rest of them, forget it.
With this type of variability, it's a challenge to even properly
evaluate an MPPT algorithm, operating in situ.

https://www.dropbox.com/sh/mprcp9exjhmjt7o/AAD_mR5iSzSj1YvkDCt_u_Cma?dl=1

BTW, my simple scheme worked particularly well in poor weather,
managing add battery charge even under dark rainy conditions.
Some schemes may do well in the range of 50 to 100% of maximum,
but the plots show how that can be a small fraction of the time.


--
Thanks,
- Win

 

[Klaus Kragelund]

I did a MPPT for the ESA Rosetta deep space mission, we had better than 1% deviation from the maximum power point

I invented a circuit to get that accuracy even with high solar array capacitance, which normally is a big problem for fast MPPT action

Cheers

Klaus

 

[Klaus Kragelund]

And efficiency counts

If you gain 10%, you can effectively reduce your investment by a lot of money

If the MPPT has slow reaction, you can loose a lot more than 10%

 

On Saturday, 2 November 2019 22:27:17 UTC, John S wrote:

On 11/2/2019 4:49 PM, amdx wrote:
On 11/2/2019 2:33 PM, whit3rd wrote:
On Saturday, November 2, 2019 at 12:03:47 AM UTC-7, Martin Riddle wrote:

On Fri, 1 Nov 2019 13:19:32 -0700 (PDT), "dcaster@krl.org"
dcaster@krl.org> wrote:

... Seems like a good project,...t to provide a little heat to the
basement.  So it would just be solar panels connected to a resistive
load.


Hot water solar collectors are the most efficient out of all solar
things. Most bang for the buck too. They move more heat than PV'S
could.

Absolutely, if you want area heat, solar HEATING of water for pumped
circulation
to the basement is a good idea.   It's as effective as a south-facing
basement
window...  except you can turn it off in the summer.  Mirror area is
cheaper
than solar-panel area, and there's black vacuum-insulated glass tubes
that
are wonderfully effective at heating a water-based fluid (you want
some antifreeze).

For my basement, though, i'm  more concerned with moisture; it has a
resident
dehumidifier.


Why not just heat the air and move it where you want it.
Assuming that won't be far.
                     Mikek

Heating the air does not remove the moisture. The water content in the
air stays constant, just the *relative* humidity goes down. To remove
the moisture you must cool the air to below the dew point. You can then
heat the air if needed.

some half truths there

 

[Winfield Hill]

Klaus Kragelund wrote...

I did a MPPT for the ESA Rosetta deep space mission, we
had better than 1% deviation from the maximum power point

There's a place where making an investment is worthwhile.


--
Thanks,
- Win

 

[Rick C]

On Sunday, November 3, 2019 at 4:32:49 AM UTC-5, Martin Brown wrote:

On 01/11/2019 20:19, dcaster@krl.org wrote:
I think about doing a lot of things that I never actually undertake. And Solar Collectors are one example of this. Seems like a good project, but it also seems like a bunch of work. So another idea is using solar panels in a super simple way. Not to replace electricity, but to provide a little heat to the basement. So it would just be solar panels connected to a resistive load. No battery storage, no inverter, no temperature control.

AliExpress or maybe it is Ebay has ads for 100 6 inch by 6 inch solar cells for about $100. So could make 4 panels , 2 feet by 3 feet to hold 24 solar cells on each panel. Maybe run lines for each panel to the basement..

Anyone see an obvious fault with the idea?

The poor intrinsic efficiency of the PV cells means that a well
insulated black painted flat radiator under glass perhaps followed by a
parabolic trough with a black pipe at the centre will capture a far
greater proportion of solar energy and deliver it as hot water (or
antifreeze mix). Kingspan, a pump and mild steel radiators are cheaper.

Plenty of designs about usually for heating swimming pools or bulk
thermal stores.

I'm sure there are lots of ways to do this job more efficiently, but really? You want the guy to run plumbing instead of wires for a 300 watt heater?

--

Rick C.

+--+ Get 1,000 miles of free Supercharging
+--+ Tesla referral code - https://ts.la/richard11209

 

[Winfield Hill]

Klaus Kragelund wrote...

In our design, the cost was very low. Significant below 1USD.

I seem to remember that you gave us some details about this,
but checking in my Klaus Kragelund folder, where I've saved
quite a bit of other stuff, there's nothing about MPPT.


--
Thanks,
- Win

 

[Klaus Kragelund]

In our design, the cost was very low. Significant below 1USD

 

[Winfield Hill]

stratus46 wrote...

The bottom line is to get heat where you want it. While you're
correct about efficiency you're being a bit pedantic. The heat
pump will get more heat into the house than the resistor.

I can attest to the practicality of heat pumps. When we were
replacing our HVAC system a few years ago, it was pointed out
that purchasing a heat pump, instead of a simple compressor,
would cost only a few hundred dollars more. Now whenever the
outside temp is 40F or above, all our home heating is done
with the heat pump. It draws 5kW when running, and heats at
about half the rate of our oil furnace (the air-duct blower
runs more slowly in the heat-pump mode). I'm a heatpump fan.


--
Thanks,
- Win

 

[Klaus Kragelund]

On Sunday, November 3, 2019 at 6:18:00 PM UTC+1, Winfield Hill wrote:

Klaus Kragelund wrote...

In our design, the cost was very low. Significant below 1USD.

I seem to remember that you gave us some details about this,
but checking in my Klaus Kragelund folder, where I've saved
quite a bit of other stuff, there's nothing about MPPT.

It was in this thread:

https://groups.google.com/forum/#!searchin/sci.electronics.design/MPPT$20klaus%7Csort:date/sci.electronics.design/h6Zr_gjzMbU/5oVuYYoyBQAJ

And this was the comment:

>What we did was something like this:

https://www.researchgate.net/publication/260541834_One-Cycle-Controlled_Single-Stage_Single-Phase_Voltage-Sensorless_Grid-Connected_PV_System

A non-microcontroller system, which is controlled by small pertubation >around the MPPT point. MPPT point is in principe found when Di/dt = dV/dt

For space applications we could not rely on, and in fact did not have a >microcontroller handy

The converter was a super-buck converter, with low input ripple current

I am not allowed to tell you exactly how it works, but I will try to see if I can find someone doing something similar, and post that

Cheers

Klaus

 

[Klaus Kragelund]

On Sunday, November 3, 2019 at 11:09:01 PM UTC+1, Klaus Kragelund wrote:

On Sunday, November 3, 2019 at 6:18:00 PM UTC+1, Winfield Hill wrote:
Klaus Kragelund wrote...

In our design, the cost was very low. Significant below 1USD.

I seem to remember that you gave us some details about this,
but checking in my Klaus Kragelund folder, where I've saved
quite a bit of other stuff, there's nothing about MPPT.




It was in this thread:

https://groups.google.com/forum/#!searchin/sci.electronics.design/MPPT$20klaus%7Csort:date/sci.electronics.design/h6Zr_gjzMbU/5oVuYYoyBQAJ

And this was the comment:

What we did was something like this:

https://www.researchgate.net/publication/260541834_One-Cycle-Controlled_Single-Stage_Single-Phase_Voltage-Sensorless_Grid-Connected_PV_System

A non-microcontroller system, which is controlled by small pertubation >around the MPPT point. MPPT point is in principe found when Di/dt = dV/dt

For space applications we could not rely on, and in fact did not have a >microcontroller handy

The converter was a super-buck converter, with low input ripple current

I am not allowed to tell you exactly how it works, but I will try to see if I can find someone doing something similar, and post that

Cheers

Klaus

Ha, it is actually shown in a document from Terma, VERY close to the actual circuit:

https://www.terma.com/media/177686/array_power_regulation_module.pdf

I remembered incorrectly, it was not 99%, but minimum 99.7% MPPT point tracking requirement

AFAIR is was tracking at 100Hz

The superbuck converter is also shown

Cheers

Klaus

 

[Bill Sloman]

On Monday, November 4, 2019 at 3:48:17 AM UTC+11, tabb...@gmail.com wrote:

On Saturday, 2 November 2019 22:27:17 UTC, John S wrote:
On 11/2/2019 4:49 PM, amdx wrote:
On 11/2/2019 2:33 PM, whit3rd wrote:
On Saturday, November 2, 2019 at 12:03:47 AM UTC-7, Martin Riddle wrote:

On Fri, 1 Nov 2019 13:19:32 -0700 (PDT), "dcaster@krl.org"
dcaster@krl.org> wrote:

... Seems like a good project,...t to provide a little heat to the
basement.  So it would just be solar panels connected to a resistive
load.


Hot water solar collectors are the most efficient out of all solar
things. Most bang for the buck too. They move more heat than PV'S
could.

Absolutely, if you want area heat, solar HEATING of water for pumped
circulation
to the basement is a good idea.   It's as effective as a south-facing
basement
window...  except you can turn it off in the summer.  Mirror area is
cheaper
than solar-panel area, and there's black vacuum-insulated glass tubes
that
are wonderfully effective at heating a water-based fluid (you want
some antifreeze).

For my basement, though, i'm  more concerned with moisture; it has a
resident
dehumidifier.


Why not just heat the air and move it where you want it.
Assuming that won't be far.
                     Mikek

Heating the air does not remove the moisture. The water content in the
air stays constant, just the *relative* humidity goes down. To remove
the moisture you must cool the air to below the dew point. You can then
heat the air if needed.

some half truths there

But NT doesn't know, and can't tell us, which bits are less than perfectly accurate.

I can't find anything wrong with either statement, so this looks more like NT not understanding what is being said and.

Dehumidifiers do cool the incoming air below it's dew point. The cold, dry air is then passed over the other end of the heat-pump circuit to warm it up again (and recondense the refrigerant that little bit faster).

--
Bill Sloman, Sydney

 

On Sat, 2 Nov 2019 13:21:23 -0700 (PDT), Whoey Louie
<trader4@optonline.net> wrote:

On Saturday, November 2, 2019 at 10:09:08 AM UTC-4, dca...@krl.org wrote:
On Friday, November 1, 2019 at 5:18:33 PM UTC-4, John Larkin wrote:


Solar cells are inefficient, and resistive heaters are inefficient.
The sunlight is hot already, so maybe use a hot water loop, basically
a solar water heater.

I guess a solar cell could run a small circulating pump.


--
On Friday, November 1, 2019 at 5:18:33 PM UTC-4, John Larkin wrote:


Solar cells are inefficient, and resistive heaters are inefficient.
The sunlight is hot already, so maybe use a hot water loop, basically
a solar water heater.

I guess a solar cell could run a small circulating pump.


--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com



John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

You are right. Solar cells are inefficient. The ones thaOn Friday, November 1, 2019 at 5:18:33 PM UTC-4, John Larkin wrote:


Solar cells are inefficient, and resistive heaters are inefficient.
The sunlight is hot already, so maybe use a hot water loop, basically
a solar water heater.

I guess a solar cell could run a small circulating pump.


--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com


t caught my eye say just over 20 %. But solar collectors are not 100% efficient. And plumbing solar collectors is a lot more work. Here ( Delaware ) you either have to drain the system at night so it does not freeze or have an expansion tank to so you can use antifreeze .

Dan

How is the need for an expansion tank dependent on whether the fluid is
water or a mix of water and antifreeze?

Heat exchanger? I'd think an expansion tank would be needed in any
case.

 

On Sat, 2 Nov 2019 16:08:21 -0700 (PDT), Rick C
<gnuarm.deletethisbit@gmail.com> wrote:

On Saturday, November 2, 2019 at 4:25:01 PM UTC-4, Whoey Louie wrote:
On Saturday, November 2, 2019 at 2:40:55 PM UTC-4, Rick C wrote:
On Saturday, November 2, 2019 at 12:34:13 PM UTC-4, jla...@highlandsniptechnology.com wrote:

Sunlight looks bright, but it's low density intermittent energy and
hard to apply. It's even worse in winter. Better to insulate the
basement, probably.

Basements are typically not insulated because being below ground they are close to the optimum temperature. Only above ground walls are insulated.

Only if you think ~55F is the optimum temperature. Otherwise a basement
is like having an uninsulated living space when it's 55F outside.
Actually it's worse than that, because when it's 55F outside, sunlight
is a big help in warming the living space. In the basement you don't
have that. IMO, it most of the US if you're going to finish the basement
and use it as living space, you'd be nuts not to insulate it.

Where is this that basement walls are a magic 55F? I know in Vermont,
the frost line can get down to at least 7'. ...and yes, in much of
the country basement walls *are* insulated if it's finished living
space.

It would appear the majority of homes built in the
US were built by nuts then. The thermal load of a concrete wall with 55°F on the other side is not so large really. In fact, most spaces need to be cooled if they don't have a path for the internally generated heat to escape. Don't try to compare an insulated wall with a huge thermal hole in it (windows) to a basement wall. Temps inside don't really need heat until the outside temps get fairly cool, below 55°F. As someone mentioned, it is the dampness of basements that gets to you more.

Where does this magic 55F dirt come from?

 

On Monday, 4 November 2019 01:20:14 UTC, Bill Sloman wrote:

On Monday, November 4, 2019 at 3:48:17 AM UTC+11, tabby wrote:
On Saturday, 2 November 2019 22:27:17 UTC, John S wrote:

Heating the air does not remove the moisture. The water content in the
air stays constant, just the *relative* humidity goes down. To remove
the moisture you must cool the air to below the dew point. You can then
heat the air if needed.

some half truths there

But NT doesn't know, and can't tell us, which bits are less than perfectly accurate.

Sure I can. And for once I will reply despite your childishness.

I can't find anything wrong with either statement, so this looks more like NT not understanding what is being said and.

Dehumidifiers do cool the incoming air below it's dew point. The cold, dry air is then passed over the other end of the heat-pump circuit to warm it up again (and recondense the refrigerant that little bit faster).

Heating air doesn't directly change its moisture content, though it does lower its RH. But heated indoor air inevitably exchanges with outdoor air in domestic properties, which is on average lower in moisture content, and which then drops RH as it warms. Exchange between heated indoor air & unheated outdoor air is the mechanism by which the great majority of houses are dehumidified.

Dehumidifiers do cool the incoming air below it's dew point. The cold, dry

To remove
the moisture you must cool the air to below the dew point.

Not really, on both counts there are other options too. Desiccant wheel dehumidifiers don't use chilling at all. Nor do box-of-salt type ones, even though they're of minimal use.

I know from Bill's history here that any moment of sense from him is merely an invitation to enter into his spiral of madness. I'm not interested in doing so & don't care what he has to say.


NT

 

[Chris Jones]

On 04/11/2019 09:25, Klaus Kragelund wrote:

On Sunday, November 3, 2019 at 11:09:01 PM UTC+1, Klaus Kragelund wrote:
On Sunday, November 3, 2019 at 6:18:00 PM UTC+1, Winfield Hill wrote:
Klaus Kragelund wrote...

In our design, the cost was very low. Significant below 1USD.

I seem to remember that you gave us some details about this,
but checking in my Klaus Kragelund folder, where I've saved
quite a bit of other stuff, there's nothing about MPPT.




It was in this thread:

https://groups.google.com/forum/#!searchin/sci.electronics.design/MPPT$20klaus%7Csort:date/sci.electronics.design/h6Zr_gjzMbU/5oVuYYoyBQAJ

And this was the comment:

What we did was something like this:

https://www.researchgate.net/publication/260541834_One-Cycle-Controlled_Single-Stage_Single-Phase_Voltage-Sensorless_Grid-Connected_PV_System

A non-microcontroller system, which is controlled by small pertubation >around the MPPT point. MPPT point is in principe found when Di/dt = dV/dt

For space applications we could not rely on, and in fact did not have a >microcontroller handy

The converter was a super-buck converter, with low input ripple current

I am not allowed to tell you exactly how it works, but I will try to see if I can find someone doing something similar, and post that

Cheers

Klaus

Ha, it is actually shown in a document from Terma, VERY close to the actual circuit:

https://www.terma.com/media/177686/array_power_regulation_module.pdf

I remembered incorrectly, it was not 99%, but minimum 99.7% MPPT point tracking requirement

AFAIR is was tracking at 100Hz

The superbuck converter is also shown

Cheers

Klaus

It finds the maximum power point within 0.3%, but the losses of the
DC-DC converter are up to 5%. To maximise the output power, it might
have been worthwhile putting more effort into the latter and less into
the former.

I once worked on a system where bypassing the MPPT DC-DC converter
greatly increased the efficiency, because the maximum power point of the
solar panel matched the battery voltage well under normal conditions,
and the MPPT was not very efficient and had awful dynamic behaviour.

 

[Whoey Louie]

On Saturday, November 2, 2019 at 11:31:03 PM UTC-4, Jasen Betts wrote:

On 2019-11-02, Whoey Louie <trader4@optonline.net> wrote:
On Saturday, November 2, 2019 at 10:09:08 AM UTC-4, dca...@krl.org wrote:
On Friday, November 1, 2019 at 5:18:33 PM UTC-4, John Larkin wrote:


Solar cells are inefficient, and resistive heaters are inefficient.
The sunlight is hot already, so maybe use a hot water loop, basically
a solar water heater.

I guess a solar cell could run a small circulating pump.


--
On Friday, November 1, 2019 at 5:18:33 PM UTC-4, John Larkin wrote:


Solar cells are inefficient, and resistive heaters are inefficient.
The sunlight is hot already, so maybe use a hot water loop, basically
a solar water heater.

I guess a solar cell could run a small circulating pump.


--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com



John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

You are right. Solar cells are inefficient. The ones thaOn Friday, November 1, 2019 at 5:18:33 PM UTC-4, John Larkin wrote:


Solar cells are inefficient, and resistive heaters are inefficient.
The sunlight is hot already, so maybe use a hot water loop, basically
a solar water heater.

I guess a solar cell could run a small circulating pump.


--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com


t caught my eye say just over 20 %. But solar collectors are not 100% efficient. And plumbing solar collectors is a lot more work. Here ( Delaware ) you either have to drain the system at night so it does not freeze or have an expansion tank to so you can use antifreeze .

Dan

How is the need for an expansion tank dependent on whether the fluid is
water or a mix of water and antifreeze?

if you don't use antifreeze it can be directly connected to the house
water supply.

Idk anywhere that code allows a heating water system to be connected to the potable water system without a backflow preventer. Which means you need an expansion tank anyway.





--
> When I tried casting out nines I made a hash of it.