Super Simple Solar Energy

[John S]

On 11/2/2019 9:25 AM, John S wrote:

On 11/2/2019 9:03 AM, upsidedown@downunder.com wrote:
On Sat, 2 Nov 2019 08:45:25 -0500, John S <Sophi.2@invalid.org> wrote:

On 11/2/2019 8:25 AM, Klaus Kragelund wrote:
Resistive load won’t operate at the maximum power point

If you overshoot, power goes way down


Overshoot what? I assumed a resistor of appropriate value connected
directly to a solar panel.

If the illumination level drops, the I/V curve "knee" (MPP) will also
move and the fixed resistor will overload the panel.


The panel cannot be overloaded. It is a constant current source and will
survive a short circuit on its output.

I should have said that the constant current is a function of the
insolation. If the insolation drops, the current will go down if the
panel is attached to a resistor.

 

[John S]

On 11/2/2019 9:03 AM, upsidedown@downunder.com wrote:

On Sat, 2 Nov 2019 08:45:25 -0500, John S <Sophi.2@invalid.org> wrote:

On 11/2/2019 8:25 AM, Klaus Kragelund wrote:
Resistive load won’t operate at the maximum power point

If you overshoot, power goes way down


Overshoot what? I assumed a resistor of appropriate value connected
directly to a solar panel.

If the illumination level drops, the I/V curve "knee" (MPP) will also
move and the fixed resistor will overload the panel.

The panel cannot be overloaded. It is a constant current source and will
survive a short circuit on its output.

 

[John S]

On 11/2/2019 8:25 AM, Klaus Kragelund wrote:

Resistive load won’t operate at the maximum power point

If you overshoot, power goes way down

Overshoot what? I assumed a resistor of appropriate value connected
directly to a solar panel.

 

On Sat, 2 Nov 2019 08:45:25 -0500, John S <Sophi.2@invalid.org> wrote:

On 11/2/2019 8:25 AM, Klaus Kragelund wrote:
Resistive load won’t operate at the maximum power point

If you overshoot, power goes way down


Overshoot what? I assumed a resistor of appropriate value connected
directly to a solar panel.

If the illumination level drops, the I/V curve "knee" (MPP) will also
move and the fixed resistor will overload the panel.

 

[dcaster@krl.org]

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

 

[Carl]

wrote in message
news:8f0f1346-1689-4feb-a772-a27415c72d03@googlegroups.com...

On Friday, November 1, 2019 at 9:04:29 PM UTC-4, Carl wrote:
wrote in message
news:ede86b9f-9053-4db7-a785-e97a766c7f17@googlegroups.com...

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

You will have to do the soldering together and mounting them into useable
panels, and adding a protective cover sheet of glass. How many watts
will
these provide, compared to the cheap 100 watt panels on amazon for
$90-100
USD? Lots of reviews and youtube videos testing these, and they seem to
be
good. If you got 400 W total from the aliexpress cells you would be
saving
$300, then doing all that labor - your choice.

Efficiency-wise, using solar heat directly is definitely more efficient
but
a lot more work. Now you have panel plumbing plus controller wiring plus
adding radiators and a pump if you don't already have hot water heating,
and
dealing with freezing if it gets that cold where you are. I always
assumed
that either using air heating panels or a water collector would be the
way
to go, but apparently PV cells have gotten cheap enough that some people
are
using them for heating water. Just add a few more PV panels to make up
for
the lower efficiency and avoid all the plumbing costs and hassles. One
example video doing this for domestic hot water is this one:
https://www.youtube.com/watch?v=YSupSNhk02A, plus a couple of followups.
He
used an MPPT controller designed just for this, driving the lower heating
element in a standard US-style two element electric water heater. This
is
sold by the developer through his website www.techluck.com, or through
the
ebay store TechLuck. It doesn't drive the heater at full power but since
it
is heating all the time the sun is shining it gets the job done and keeps
the tank hot. You just set the thermostat on that heater up the the
maximum
safe temp for the tank and let it go. Make the tank big enough to still
have enough hot water for the morning showers and the second heater still
connected to the mains won't ever come on. Lots of info at the website
on
PV array sizes, heater wattages, etc. MPPT is definitely the best way to
extract power from the PV panels so I recommend either his controller or
some other, to drive your heaters.

I haven't done this myself, I just like researching and learning about
stuff, that's why I lurk here .

--
Regards,
Carl Ijames
c

You understand the trade offs. I had not seen anything about MPPT'n and it
sounds adding one of them would be cost effective. And easy to add at any
time.

Thanks,

Dan

Forgot to mention that the other advantage of PV for heating is that the
effectiveness of the PV system doesn't drop off as the ambient temperature
falls, like a direct heat collection system will. There, the system output
temperature is a fairly fixed rise over the ambient temperature so on a
really cold day you may be cold too . With the PV system the output
should actually rise a bit as the panel cools compared to summer peak panel
temperatures (I'm sure it will fall again at some really cold temperature
but I don't know what that would be or if it matters for this).

--
Regards,
Carl Ijames

 

On Sat, 2 Nov 2019 09:25:12 -0500, John S <Sophi.2@invalid.org> wrote:

On 11/2/2019 9:03 AM, upsidedown@downunder.com wrote:
On Sat, 2 Nov 2019 08:45:25 -0500, John S <Sophi.2@invalid.org> wrote:

On 11/2/2019 8:25 AM, Klaus Kragelund wrote:
Resistive load won’t operate at the maximum power point

If you overshoot, power goes way down


Overshoot what? I assumed a resistor of appropriate value connected
directly to a solar panel.

If the illumination level drops, the I/V curve "knee" (MPP) will also
move and the fixed resistor will overload the panel.


The panel cannot be overloaded. It is a constant current source and will
survive a short circuit on its output.

At some illumination level, there is an optimum load current. Anything
else wastes power. A solar cell is not a constant-current source.

For a (silly) resistive heater, one could add a big cap and PWM the
heater to find the sweet spot.




--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

On Sat, 2 Nov 2019 07:09:03 -0700 (PDT), "dcaster@krl.org"
<dcaster@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

I suppose you could blow air through a collector, a simple
greenhouse-type box maybe. Is that done?

The energy that powers the fan would just act like a bit of extra
resistive heating.

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.



--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

On Sat, 2 Nov 2019 00:11:27 -0700 (PDT), Phil Allison
<pallison49@gmail.com> wrote:

John Larkin = Pathetic Excuse for a Bullshitter wrote:

-----------------------------------------------------




Solar cells are inefficient, and resistive heaters are inefficient.


** Really ?

Other than heat, what do resistive heaters convert electricity into ?

Far IR light?


..... Phil

Some people claim that resistive heating is 100% efficient.


** Like all the scientists and engineers, even high school students.


Then a heat pump must be 400% efficient.


** JL must be a true genius.

He just proved 2+2 = 5

Wot a scumbag.


..... Phil

https://en.wikipedia.org/wiki/Heat_pump


According to the US United States Environmental Protection Agency
(EPA), geothermal heat pumps can reduce energy consumption up to 44%
compared with air-source heat pumps and up to 72% compared with
electric resistance heating.[35] The COP for heat pumps range from 3.2
to 4.5 for air source heat pumps to 4.2 to 5.2 for ground source heat
pumps.[36]

When used for heating a building with an outside temperature of, for
example, 10 °C, a typical air-source heat pump (ASHP) has a COP of 3
to 4, whereas an electrical resistance heater has a COP of 1.0. That
is, to produce one joule of useful heat, a resistance heater needs one
joule of electrical energy, while a heat pump under conditions where
its COP is 3 or 4 would require only a 0.33 or 0.25 joules of
electrical energy, the difference being taken from the cooler place.



--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

On 2 Nov 2019 09:47:38 -0700, Winfield Hill <winfieldhill@yahoo.com>
wrote:

dcaster@krl.org wrote...

You understand the trade offs. I had not seen anything
about MPPT'n and it sounds adding one of them would be
cost effective. And easy to add at any time.

You will see a dramatic difference between using a fixed
load resistance, and some form of MPPT. But I was able
to create of form of pseudo MPPT, that's only about 10
to 15% worse than perfect MPPT. To illustrate my scheme
I'll use the values I implemented, to charge the Li-ion
battery in my bee-hive monitor. My sources are nominal
12V solar panels with various capacities. An important
first step is an electrolytic cap charged by the panels.
This holds the node voltage during high converter current
pulses. I used 470uF 25V to handle up to 20W panels.
Next a Schottky diode to handle reverse polarity wiring.
Followed by an efficient buck converter setup to create
a 4.6-volt charging voltage. Next an important item, an
accurate UVLO to shutoff the buck converter whenever the
470uF elec voltage drops below 10 volts. I used a TI
TPS54202H, which has an accurate 1.28V cutoff, with two
1% resistors to set the 10V (or maybe 11V). It's the
hiccuping of the buck converter that implements MPPT.

Finally there's a charging-controller IC, setting the
maximum Li-ion charging current, limiting its voltage
to 4.3 volts. The equivalent in your case would be a
fixed resistor on the 4.6-volt output. When there's
insufficient solar, the buck converter cuts out and
the 4.6-volts drops, but the solar panel is always
operating with a load from 10 to 13 volts, even with
an overcast sky, and it's delivering close to its
maximum available power.

It would make more sense for him to install a standard solar system,
into the AC line, and go to Walgreens and get a little electric heater
for the basement.




--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

[Winfield Hill]

dcaster@krl.org wrote...

You understand the trade offs. I had not seen anything
about MPPT'n and it sounds adding one of them would be
cost effective. And easy to add at any time.

You will see a dramatic difference between using a fixed
load resistance, and some form of MPPT. But I was able
to create of form of pseudo MPPT, that's only about 10
to 15% worse than perfect MPPT. To illustrate my scheme
I'll use the values I implemented, to charge the Li-ion
battery in my bee-hive monitor. My sources are nominal
12V solar panels with various capacities. An important
first step is an electrolytic cap charged by the panels.
This holds the node voltage during high converter current
pulses. I used 470uF 25V to handle up to 20W panels.
Next a Schottky diode to handle reverse polarity wiring.
Followed by an efficient buck converter setup to create
a 4.6-volt charging voltage. Next an important item, an
accurate UVLO to shutoff the buck converter whenever the
470uF elec voltage drops below 10 volts. I used a TI
TPS54202H, which has an accurate 1.28V cutoff, with two
1% resistors to set the 10V (or maybe 11V). It's the
hiccuping of the buck converter that implements MPPT.

Finally there's a charging-controller IC, setting the
maximum Li-ion charging current, limiting its voltage
to 4.3 volts. The equivalent in your case would be a
fixed resistor on the 4.6-volt output. When there's
insufficient solar, the buck converter cuts out and
the 4.6-volts drops, but the solar panel is always
operating with a load from 10 to 13 volts, even with
an overcast sky, and it's delivering close to its
maximum available power.



--
Thanks,
- Win

 

[Rick C]

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.

John doesn't like solar power so he knocks it. His claim of it being "hard to apply" is directly in contradiction of the OP who is looking for a simple solution. In this case I think PV solar may be an easy approach. The only issue is whether it is cost effective or not.

So far the only issue will be finding a MPPT load device.

--

Rick C.

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

 

[Rick C]

On Saturday, November 2, 2019 at 10:30:00 AM UTC-4, John S wrote:

On 11/2/2019 9:25 AM, John S wrote:
On 11/2/2019 9:03 AM, upsidedown@downunder.com wrote:
On Sat, 2 Nov 2019 08:45:25 -0500, John S <Sophi.2@invalid.org> wrote:

On 11/2/2019 8:25 AM, Klaus Kragelund wrote:
Resistive load won’t operate at the maximum power point

If you overshoot, power goes way down


Overshoot what? I assumed a resistor of appropriate value connected
directly to a solar panel.

If the illumination level drops, the I/V curve "knee" (MPP) will also
move and the fixed resistor will overload the panel.


The panel cannot be overloaded. It is a constant current source and will
survive a short circuit on its output.

I should have said that the constant current is a function of the
insolation. If the insolation drops, the current will go down if the
panel is attached to a resistor.

Look up the I/V curve for a solar array or cell. It is only constant current up to the knee of the curve where the max voltage is approached and the current drops off dramatically. At that point it is constant voltage.

Even so, in the constant current range the voltage drops off dramatically. Maximum power is at a point on the knee between the two.

--

Rick C.

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

 

[Rick C]

On Saturday, November 2, 2019 at 9:25:47 AM UTC-4, Klaus Kragelund wrote:

Resistive load won’t operate at the maximum power point

If you overshoot, power goes way down

That is very true. In fact, you need a maximum power point tracking (MPPT) load. If you try to draw a fixed amount of power and the solar cell can't deliver that, the resulting power provided goes down a lot more than it should. Draw too much current and the voltage drops disproportionately.

They make MPPT controllers, but they still will only put out some fixed voltage and for any given lighting condition you won't get optimum power. So in reality you need a MPPT load device instead. Not hard conceptually. It's basically a switching regulator but the thing being controlled is power to the load rather than voltage or current. Use a low resistance load and a standard buck topology can be used. A small MCU can measure the voltage and current into the load and dither it to find the optimum power point.

--

Rick C.

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

 

[Rick C]

On Saturday, November 2, 2019 at 1:02:57 PM UTC-4, jla...@highlandsniptechnology.com wrote:

On 2 Nov 2019 09:47:38 -0700, Winfield Hill <winfieldhill@yahoo.com
wrote:

dcaster@krl.org wrote...

You understand the trade offs. I had not seen anything
about MPPT'n and it sounds adding one of them would be
cost effective. And easy to add at any time.

You will see a dramatic difference between using a fixed
load resistance, and some form of MPPT. But I was able
to create of form of pseudo MPPT, that's only about 10
to 15% worse than perfect MPPT. To illustrate my scheme
I'll use the values I implemented, to charge the Li-ion
battery in my bee-hive monitor. My sources are nominal
12V solar panels with various capacities. An important
first step is an electrolytic cap charged by the panels.
This holds the node voltage during high converter current
pulses. I used 470uF 25V to handle up to 20W panels.
Next a Schottky diode to handle reverse polarity wiring.
Followed by an efficient buck converter setup to create
a 4.6-volt charging voltage. Next an important item, an
accurate UVLO to shutoff the buck converter whenever the
470uF elec voltage drops below 10 volts. I used a TI
TPS54202H, which has an accurate 1.28V cutoff, with two
1% resistors to set the 10V (or maybe 11V). It's the
hiccuping of the buck converter that implements MPPT.

Finally there's a charging-controller IC, setting the
maximum Li-ion charging current, limiting its voltage
to 4.3 volts. The equivalent in your case would be a
fixed resistor on the 4.6-volt output. When there's
insufficient solar, the buck converter cuts out and
the 4.6-volts drops, but the solar panel is always
operating with a load from 10 to 13 volts, even with
an overcast sky, and it's delivering close to its
maximum available power.


It would make more sense for him to install a standard solar system,
into the AC line, and go to Walgreens and get a little electric heater
for the basement.

A classic illustration of completely not understanding the problem.

--

Rick C.

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

 

On Saturday, November 2, 2019 at 10:02:57 AM UTC-7, jla...@highlandsniptechnology.com wrote:

On 2 Nov 2019 09:47:38 -0700, Winfield Hill <winfieldhill@yahoo.com
wrote:

dcaster@krl.org wrote...

You understand the trade offs. I had not seen anything
about MPPT'n and it sounds adding one of them would be
cost effective. And easy to add at any time.

You will see a dramatic difference between using a fixed
load resistance, and some form of MPPT. But I was able
to create of form of pseudo MPPT, that's only about 10
to 15% worse than perfect MPPT. To illustrate my scheme
I'll use the values I implemented, to charge the Li-ion
battery in my bee-hive monitor. My sources are nominal
12V solar panels with various capacities. An important
first step is an electrolytic cap charged by the panels.
This holds the node voltage during high converter current
pulses. I used 470uF 25V to handle up to 20W panels.
Next a Schottky diode to handle reverse polarity wiring.
Followed by an efficient buck converter setup to create
a 4.6-volt charging voltage. Next an important item, an
accurate UVLO to shutoff the buck converter whenever the
470uF elec voltage drops below 10 volts. I used a TI
TPS54202H, which has an accurate 1.28V cutoff, with two
1% resistors to set the 10V (or maybe 11V). It's the
hiccuping of the buck converter that implements MPPT.

Finally there's a charging-controller IC, setting the
maximum Li-ion charging current, limiting its voltage
to 4.3 volts. The equivalent in your case would be a
fixed resistor on the 4.6-volt output. When there's
insufficient solar, the buck converter cuts out and
the 4.6-volts drops, but the solar panel is always
operating with a load from 10 to 13 volts, even with
an overcast sky, and it's delivering close to its
maximum available power.


It would make more sense for him to install a standard solar system,
into the AC line, and go to Walgreens and get a little electric heater
for the basement.

Yes, my lazy solution: $100 150W stick on flexible panel + $100 300W micro inverter + $10 heater.

Installation: clean the roof, roll out (17' x 1.5') and stick it on, connect MC4 to micro inverter, plug inverter output into outdoor light or A/C outlet, plug in heater in basement.

 

On Sat, 2 Nov 2019 11:11:15 -0700 (PDT), edward.ming.lee@gmail.com
wrote:

On Saturday, November 2, 2019 at 10:02:57 AM UTC-7, jla...@highlandsniptechnology.com wrote:
On 2 Nov 2019 09:47:38 -0700, Winfield Hill <winfieldhill@yahoo.com
wrote:

dcaster@krl.org wrote...

You understand the trade offs. I had not seen anything
about MPPT'n and it sounds adding one of them would be
cost effective. And easy to add at any time.

You will see a dramatic difference between using a fixed
load resistance, and some form of MPPT. But I was able
to create of form of pseudo MPPT, that's only about 10
to 15% worse than perfect MPPT. To illustrate my scheme
I'll use the values I implemented, to charge the Li-ion
battery in my bee-hive monitor. My sources are nominal
12V solar panels with various capacities. An important
first step is an electrolytic cap charged by the panels.
This holds the node voltage during high converter current
pulses. I used 470uF 25V to handle up to 20W panels.
Next a Schottky diode to handle reverse polarity wiring.
Followed by an efficient buck converter setup to create
a 4.6-volt charging voltage. Next an important item, an
accurate UVLO to shutoff the buck converter whenever the
470uF elec voltage drops below 10 volts. I used a TI
TPS54202H, which has an accurate 1.28V cutoff, with two
1% resistors to set the 10V (or maybe 11V). It's the
hiccuping of the buck converter that implements MPPT.

Finally there's a charging-controller IC, setting the
maximum Li-ion charging current, limiting its voltage
to 4.3 volts. The equivalent in your case would be a
fixed resistor on the 4.6-volt output. When there's
insufficient solar, the buck converter cuts out and
the 4.6-volts drops, but the solar panel is always
operating with a load from 10 to 13 volts, even with
an overcast sky, and it's delivering close to its
maximum available power.


It would make more sense for him to install a standard solar system,
into the AC line, and go to Walgreens and get a little electric heater
for the basement.

Yes, my lazy solution: $100 150W stick on flexible panel + $100 300W micro inverter + $10 heater.

Installation: clean the roof, roll out (17' x 1.5') and stick it on, connect MC4 to micro inverter, plug inverter output into outdoor light or A/C outlet, plug in heater in basement.

The little heaters are usually around a kilowatt or so. 150 watts
isn't much heat.




--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

[whit3rd]

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.

 

[Winfield Hill]

Rick C wrote...

Yes, my lazy solution: $100 150W stick on flexible
panel + $100 300W micro inverter + $10 heater.

Too bad it won't work.

Of course it can "work". If he controls the heater
carefully enough, he can match its on-average energy
use to the solar energy from his panel into the grid.
But it may not heat up his basement, very much.



--
Thanks,
- Win

 

On Saturday, November 2, 2019 at 11:52:51 AM UTC-7, Rick C wrote:

On Saturday, November 2, 2019 at 2:11:20 PM UTC-4, edward...@gmail.com wrote:
On Saturday, November 2, 2019 at 10:02:57 AM UTC-7, jla...@highlandsniptechnology.com wrote:
On 2 Nov 2019 09:47:38 -0700, Winfield Hill <winfieldhill@yahoo.com
wrote:

dcaster@krl.org wrote...

You understand the trade offs. I had not seen anything
about MPPT'n and it sounds adding one of them would be
cost effective. And easy to add at any time.

You will see a dramatic difference between using a fixed
load resistance, and some form of MPPT. But I was able
to create of form of pseudo MPPT, that's only about 10
to 15% worse than perfect MPPT. To illustrate my scheme
I'll use the values I implemented, to charge the Li-ion
battery in my bee-hive monitor. My sources are nominal
12V solar panels with various capacities. An important
first step is an electrolytic cap charged by the panels.
This holds the node voltage during high converter current
pulses. I used 470uF 25V to handle up to 20W panels.
Next a Schottky diode to handle reverse polarity wiring.
Followed by an efficient buck converter setup to create
a 4.6-volt charging voltage. Next an important item, an
accurate UVLO to shutoff the buck converter whenever the
470uF elec voltage drops below 10 volts. I used a TI
TPS54202H, which has an accurate 1.28V cutoff, with two
1% resistors to set the 10V (or maybe 11V). It's the
hiccuping of the buck converter that implements MPPT.

Finally there's a charging-controller IC, setting the
maximum Li-ion charging current, limiting its voltage
to 4.3 volts. The equivalent in your case would be a
fixed resistor on the 4.6-volt output. When there's
insufficient solar, the buck converter cuts out and
the 4.6-volts drops, but the solar panel is always
operating with a load from 10 to 13 volts, even with
an overcast sky, and it's delivering close to its
maximum available power.


It would make more sense for him to install a standard solar system,
into the AC line, and go to Walgreens and get a little electric heater
for the basement.

Yes, my lazy solution: $100 150W stick on flexible panel + $100 300W micro inverter + $10 heater.

Installation: clean the roof, roll out (17' x 1.5') and stick it on, connect MC4 to micro inverter, plug inverter output into outdoor light or A/C outlet, plug in heater in basement.

Too bad it won't work.

Which part won't work?