Super Simple Solar Energy

[Whoey Louie]

On Sunday, November 3, 2019 at 9:18:19 PM UTC-5, k...@notreal.com wrote:

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.

That's the issue. Most basements aren't insulated because they are not living spaces and they are not heated. If they are, then they are generally insulated in colder climates.

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?

 

[Robert Baer]

John Larkin wrote:

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

Dan

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.

A resistor is 100 percent efficient in converting electrical power to
heat...

 

[Bill Sloman]

On Monday, November 4, 2019 at 1:15:30 PM UTC+11, tabb...@gmail.com wrote:

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.

So NT agrees that this statement was entirely correct

> 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.

This is just irrelevant carping. Out-door air was be wetter or drier than indoor air, or warmer or cooler. Swapping air with the outside world is ventilation.

> Exchange between heated indoor air & unheated outdoor air is the mechanism by which the great majority of houses are dehumidified.

It's an incidental feature of the more general process of ventilation. If you are getting worried by damp patches on the walls, dehumidifiers attack the problem directly. NT is in evasive mode here.

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 have seen both sorts of dehumidifier sold for domestic use. It's nuts, but some hardware stores cater for people with little money and even less sense. As NT admits, they don't work well enough to be of much use, and they certainly aren't cost effective.

Laboratory desiccators frequently used water absorbers which can be regenerated by heating, but strictly for tiny volumes of air.

> 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.

There's no madness involved, if we exclude NT's inane enthusiasm for unhelpful pontification.

--
Bill Sloman, Sydney

 

[Rick C]

On Sunday, November 3, 2019 at 1:40:59 PM UTC-5, Winfield Hill wrote:

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.

There is no reason to limit it to 40°F and above. The one in my father's house was set to something like that by an external dial. I changed it to go down to 32°F and it kept the place quite warm. The thermodynamics of a heat pump aren't significantly worse at lower temperatures. It is simply that the capacity is reduced because it is having to push the heat further uphill to the inside, so less heat is actually moved. But it is still better than resistive heat. When it won't keep the house warm enough, kick in the back up heat, but no reason to turn off the heat pump... well if your back up is straight electric anyway.

Ice formation on the outside coils can happen even at 40°F, so that isn't the reason.

--

Rick C.

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

 

[Rick C]

On Sunday, November 3, 2019 at 11:02:24 PM UTC-5, Whoey Louie wrote:

On Sunday, November 3, 2019 at 9:18:19 PM UTC-5, k...@notreal.com wrote:
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.



That's the issue. Most basements aren't insulated because they are not living spaces and they are not heated. If they are, then they are generally insulated in colder climates.

That's not what I was talking about. I guess I was generalizing too much. While I think a 7 foot deep frost in Vermont is a bit overly dramatic, the 55 degree temperature is around here. In places like Vermont the underground temp is around mid 40s, so likely the full basement wall is insulated. If the freeze line really did get to 7 foot down, there would be a lot of frozen well pipes every year. They have to come up enough to enter the house at some point.

Keep in mind that while a 55°F basement wall may be a bit cool in the winter, it feels really nice in the summer. So insulating the underground portion of the wall will give a savings while heating at the expense of requiring more cooling in the summer. I expect 55°F is a very nice compromise between the two.

--

Rick C.

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

 

[Rick C]

On Monday, November 4, 2019 at 12:31:35 AM UTC-5, Robert Baer wrote:

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

Dan

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.


A resistor is 100 percent efficient in converting electrical power to
heat...

Even if it weren't, the losses would end up as... heat.

I suppose at some point a resistor will give off light that isn't IR and so will be slightly less than 100% efficient at producing heat. lol

--

Rick C.

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

 

On Monday, 4 November 2019 03:52:59 UTC+1, Chris Jones wrote:

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.

Not really. It looks bad if you are looking at a commercial design

But, this is for Space, so what a normal converter does not have is added:

Input current sense
Input current trip MOSFET
Output current sense
Output current trip MOSFET
Control and monitoring system
Old bipolar PWM controller (at that time no FET UCCxxxx controller was approved for space)
Filter for ultra low noise

All that adds up

Cheers

Klaus

 

[Chris Jones]

On 04/11/2019 20:15, klaus.kragelund@gmail.com wrote:

On Monday, 4 November 2019 03:52:59 UTC+1, Chris Jones wrote:
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.


Not really. It looks bad if you are looking at a commercial design

But, this is for Space, so what a normal converter does not have is added:

Input current sense
Input current trip MOSFET
Output current sense
Output current trip MOSFET
Control and monitoring system
Old bipolar PWM controller (at that time no FET UCCxxxx controller was approved for space)
Filter for ultra low noise

All that adds up

Cheers

Klaus

If all of the extra features you mentioned are a sort of sunk cost in
terms of efficiency, then perhaps improving the efficiency by 0.1% would
have been just as hard as improving the finding of the maximum power
point by 0.1% - in other words, if the incremental effort per
incremental watt got out of it by improving efficiency is about the same
as the incremental effort to per incremental watt out due to finding the
maximum power point more accurately, then the effort is sensibly allocated.

 

[John S]

On 11/3/2019 8:52 PM, Chris Jones wrote:

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.

I found the same thing. The panel gets hot so it gets closer to the MPP
when attached to a battery. Of course that was in a warm ambient and at
peak insolation.

 

[Martin Brown]

On 03/11/2019 17:15, Rick C wrote:

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?

It is a way more appropriate solution to the problem than the DIY solar
PV approach and would be able to supply more heat than a puny 300W.

--
Regards,
Martin Brown

 

[dcaster@krl.org]

On Monday, November 4, 2019 at 8:06:24 AM UTC-5, Martin Brown wrote:

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 3 0 0
watt heater?

It is a way more appropriate solution to the problem than the DIY solar
PV approach and would be able to supply more heat than a puny 300W.

-- ?


Regards,
Martin Brown

You are absolutely correct. But my problem with that approach is that I never get around to building the better system. I may not get around to making a PV system. but it seems like it would be a lot less work. And I think a puny 300 watts for about 3 hours a day would be enough to make the basement a pleasant place.

Maybe I should make a 300 watt heater and run it off a timers and see if that is enough. ( or just use heater that I already have and adjust the times so the heater provides one KWH per day.

Dan

Dan

 

On Monday, 4 November 2019 11:47:28 UTC+1, Chris Jones wrote:

On 04/11/2019 20:15, klaus.kragelund@gmail.com wrote:
On Monday, 4 November 2019 03:52:59 UTC+1, Chris Jones wrote:
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.


Not really. It looks bad if you are looking at a commercial design

But, this is for Space, so what a normal converter does not have is added:

Input current sense
Input current trip MOSFET
Output current sense
Output current trip MOSFET
Control and monitoring system
Old bipolar PWM controller (at that time no FET UCCxxxx controller was approved for space)
Filter for ultra low noise

All that adds up

Cheers

Klaus


If all of the extra features you mentioned are a sort of sunk cost in
terms of efficiency, then perhaps improving the efficiency by 0.1% would
have been just as hard as improving the finding of the maximum power
point by 0.1% - in other words, if the incremental effort per
incremental watt got out of it by improving efficiency is about the same
as the incremental effort to per incremental watt out due to finding the
maximum power point more accurately, then the effort is sensibly allocated.

The accuracy of 0.3% is cheap, just takes some thought. As I wrote, much lower than 1 USD

Increasing efficiency of the converter is costly, cannot be compared

Cheers

Klaus

 

[Jeroen Belleman]

klaus.kragelund@gmail.com wrote:

[Snip!]

The accuracy of 0.3% is cheap, just takes some thought. As I wrote, much lower than 1 USD

Increasing efficiency of the converter is costly, cannot be compared

Cheers

Klaus

I don't understand that circuit very well. I see two comparators,
one comparing the SA voltage with a sampled fraction of same,
the other the SA current with a sampled fraction of that current.
The comparator outputs drive an SR FF, the crossed outputs of
which drive the S/H switches and an integrator. The integrator
controls the PWM input of the power converter.

How does this converge on the maximum power point? Does it rely
on the charge of the hold capacitors drifting in some specific
way?

Thanks,
Jeroen Belleman

 

[John S]

On 11/4/2019 8:14 AM, tabbypurr@gmail.com wrote:

On Monday, 4 November 2019 05:10:32 UTC, Bill Sloman wrote:
On Monday, November 4, 2019 at 1:15:30 PM UTC+11, tabby wrote:
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.

So NT agrees that this statement was entirely correct

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.

This is just irrelevant carping. Out-door air was be wetter or drier than indoor air, or warmer or cooler. Swapping air with the outside world is ventilation.

Exchange between heated indoor air & unheated outdoor air is the mechanism by which the great majority of houses are dehumidified.

It's an incidental feature of the more general process of ventilation. If you are getting worried by damp patches on the walls, dehumidifiers attack the problem directly. NT is in evasive mode here.

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 have seen both sorts of dehumidifier sold for domestic use. It's nuts, but some hardware stores cater for people with little money and even less sense. As NT admits, they don't work well enough to be of much use, and they certainly aren't cost effective.

Laboratory desiccators frequently used water absorbers which can be regenerated by heating, but strictly for tiny volumes of air.

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.

There's no madness involved, if we exclude NT's inane enthusiasm for unhelpful pontification.


Lol. And desiccant wheel dehumidifiers work just fine.

And what do you do with the desiccant when it is saturated with water?

 

On Monday, 4 November 2019 05:10:32 UTC, Bill Sloman wrote:

On Monday, November 4, 2019 at 1:15:30 PM UTC+11, tabby wrote:
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.

So NT agrees that this statement was entirely correct

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.

This is just irrelevant carping. Out-door air was be wetter or drier than indoor air, or warmer or cooler. Swapping air with the outside world is ventilation.

Exchange between heated indoor air & unheated outdoor air is the mechanism by which the great majority of houses are dehumidified.

It's an incidental feature of the more general process of ventilation. If you are getting worried by damp patches on the walls, dehumidifiers attack the problem directly. NT is in evasive mode here.

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 have seen both sorts of dehumidifier sold for domestic use. It's nuts, but some hardware stores cater for people with little money and even less sense. As NT admits, they don't work well enough to be of much use, and they certainly aren't cost effective.

Laboratory desiccators frequently used water absorbers which can be regenerated by heating, but strictly for tiny volumes of air.

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.

There's no madness involved, if we exclude NT's inane enthusiasm for unhelpful pontification.

Lol. And desiccant wheel dehumidifiers work just fine.

 

On Monday, 4 November 2019 15:15:59 UTC+1, Jeroen Belleman wrote:

klaus.kragelund@gmail.com wrote:

[Snip!]


The accuracy of 0.3% is cheap, just takes some thought. As I wrote, much lower than 1 USD

Increasing efficiency of the converter is costly, cannot be compared

Cheers

Klaus

I don't understand that circuit very well. I see two comparators,
one comparing the SA voltage with a sampled fraction of same,
the other the SA current with a sampled fraction of that current.
The comparator outputs drive an SR FF, the crossed outputs of
which drive the S/H switches and an integrator. The integrator
controls the PWM input of the power converter.

How does this converge on the maximum power point? Does it rely
on the charge of the hold capacitors drifting in some specific
way?

When you look at the I/V curve for the solar array, you find that the maximum power point is at the curvature, where the slope is 45 degrees

To if you sample the voltage, let the converter ramp the current up linearly, until the voltage has decreased say 1%

You change direction on the 1% decrease, so now you sample current, ramp the current down, and change direction again at 1% degrease

You find that you are then operating in the MPPT point

The flipflop is just there to change the direction, and trigger the S/H circuit for either the voltage or current part

Cheers

Klaus

Cheers

Klaus

 

[Winfield Hill]

John S wrote...

tabbypurr wrote:

And desiccant wheel dehumidifiers work just fine.

And what do you do with the desiccant when it is
saturated with water?

Do they become humidifiers, when (if) the air
otherwise becomes dry again?


--
Thanks,
- Win

 

[Rick C]

On Monday, November 4, 2019 at 8:55:57 AM UTC-5, dca...@krl.org wrote:

On Monday, November 4, 2019 at 8:06:24 AM UTC-5, Martin Brown wrote:


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 3 0 0
watt heater?

It is a way more appropriate solution to the problem than the DIY solar
PV approach and would be able to supply more heat than a puny 300W.

-- ?


Regards,
Martin Brown

You are absolutely correct. But my problem with that approach is that I never get around to building the better system. I may not get around to making a PV system. but it seems like it would be a lot less work. And I think a puny 300 watts for about 3 hours a day would be enough to make the basement a pleasant place.

Maybe I should make a 300 watt heater and run it off a timers and see if that is enough. ( or just use heater that I already have and adjust the times so the heater provides one KWH per day.

I think it is a mistake to believe 300 watts will do much in your basement. I have a house that is currently vacant. A 1400 watt heater barely makes a difference in a 40x25 foot basement. I'm just trying to keep the pipes from freezing and it barely does that. In fact, I might need to turn it on..

--

Rick C.

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

 

[Rick C]

On Monday, November 4, 2019 at 8:06:24 AM UTC-5, Martin Brown wrote:

On 03/11/2019 17:15, Rick C wrote:
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?

It is a way more appropriate solution to the problem than the DIY solar
PV approach and would be able to supply more heat than a puny 300W.

It's also a lot more work for a DIY project. A LOT more work.

--

Rick C.

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

 

[Martin Brown]

On 04/11/2019 13:55, dcaster@krl.org wrote:

On Monday, November 4, 2019 at 8:06:24 AM UTC-5, Martin Brown wrote:


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
3 0 0 watt heater?

It is a way more appropriate solution to the problem than the DIY
solar PV approach and would be able to supply more heat than a puny
300W.

You are absolutely correct. But my problem with that approach is
that I never get around to building the better system. I may not get
around to making a PV system. but it seems like it would be a lot
less work. And I think a puny 300 watts for about 3 hours a day
would be enough to make the basement a pleasant place.

Maybe I should make a 300 watt heater and run it off a timers and
see if that is enough. ( or just use heater that I already have and
adjust the times so the heater provides one KWH per day.

You definitely should test it first. My guess is that a 300W heater
won't even be noticeable unless your basement is incredibly well
insulated. I'd guess you need at least 1kW and a few hours to make any
noticeable change. A 3kW fan heater would definitely make a difference.

Three 100W bulbs in an old empty oil drum will do it for a test.

As a ball park figure to get 1C rise every 10 minutes in our village
hall 12mx6mx3m requires about 16kW of active air heating. The walls are
solid Victorian engineering brick so not dissimilar to concrete.

--
Regards,
Martin Brown