Guest
On Tuesday, 15 October 2019 03:14:19 UTC+1, Bill Sloman wrote:
ah, more horseshit. Then sprinkle a fact in to make it sound credible.
ah, more horseshit. Then sprinkle a fact in to make it sound credible.
B
Bill Sloman
Guest
On Wednesday, October 16, 2019 at 9:11:28 PM UTC+11, tabb...@gmail.com wrote:
That kind of argument does go over NT's head.
--
Bill Sloman, Sydney
That kind of argument does go over NT's head.
--
Bill Sloman, Sydney
B
Bill Sloman
Guest
On Wednesday, October 16, 2019 at 9:09:39 PM UTC+11, tabb...@gmail.com wrote:
NT is the specialist in horseshit around here. He knows very little and most of what he thinks he knows seems to be wrong.
His positive opinion of his own credibility is one of the many areas where he deludes himself.
--
Bill Sloman, Sydney
NT is the specialist in horseshit around here. He knows very little and most of what he thinks he knows seems to be wrong.
His positive opinion of his own credibility is one of the many areas where he deludes himself.
--
Bill Sloman, Sydney
J
Jeroen Belleman
Guest
tabbypurr@gmail.com wrote:
A solar cell is like a (photo)current source in parallel
with a diode. The current source's polarity is in the forward
direction of the diode, which is why the voltage across a
single cell is limited to one diode forward voltage drop,
about 600mV, give or take.
To see what happens when a cell is inhomogeneously
illuminated, one could model a large cell as several small
ones in parallel. It's easy enough to see that the
photo current is proportional to the illuminated area
while the voltage is is affected only by the logarithm
of the current, that is, only a little.
In a PV panel, many cells are put in series and it's easy
to see that the current produced by one cell flows in the
reverse direction through the others. If one cell in
a series string is not illuminated, it blocks the
passage of the current from the other cells! Of course,
it's natural to include a reverse diode in each cell
to defend against such cases, but the loss is still
*two* diode drops for each dark cell, so it's important
that a panel is homogeneously illuminated.
Now I'm left wondering why no one in this discussion
took the trouble to answer this properly, but I'm sure
that several will now pipe up to pick nits.
Jeroen Belleman
A solar cell is like a (photo)current source in parallel
with a diode. The current source's polarity is in the forward
direction of the diode, which is why the voltage across a
single cell is limited to one diode forward voltage drop,
about 600mV, give or take.
To see what happens when a cell is inhomogeneously
illuminated, one could model a large cell as several small
ones in parallel. It's easy enough to see that the
photo current is proportional to the illuminated area
while the voltage is is affected only by the logarithm
of the current, that is, only a little.
In a PV panel, many cells are put in series and it's easy
to see that the current produced by one cell flows in the
reverse direction through the others. If one cell in
a series string is not illuminated, it blocks the
passage of the current from the other cells! Of course,
it's natural to include a reverse diode in each cell
to defend against such cases, but the loss is still
*two* diode drops for each dark cell, so it's important
that a panel is homogeneously illuminated.
Now I'm left wondering why no one in this discussion
took the trouble to answer this properly, but I'm sure
that several will now pipe up to pick nits.
Jeroen Belleman
Guest
On Wednesday, 16 October 2019 13:57:38 UTC+1, Jeroen Belleman wrote:
Precisely. That is why small shadows can cane the output.
If you look at a PV array's v/i curve you'll straight away see that having one string with significantly reduced V_out means it provides less current than the others - and that's a bit of an optimistic case. If your shadow or uneven illumination affects all the strings, it doesn't go well.
I don't know what %age of PV arrays have diodes to work around this, but the ones I've tried this with did not do well, so I expect they didn't have these diodes.
NT
Precisely. That is why small shadows can cane the output.
If you look at a PV array's v/i curve you'll straight away see that having one string with significantly reduced V_out means it provides less current than the others - and that's a bit of an optimistic case. If your shadow or uneven illumination affects all the strings, it doesn't go well.
I don't know what %age of PV arrays have diodes to work around this, but the ones I've tried this with did not do well, so I expect they didn't have these diodes.
NT
B
Bill Sloman
Guest
On Thursday, October 17, 2019 at 7:04:29 AM UTC+11, tabb...@gmail.com wrote:
If you look at a PV array's v/i curve without thinking about what's actually going on you can probably duplicate NT's mistake.
> I don't know what %age of PV arrays have diodes to work around this, but the ones I've tried this with did not do well, so I expect they didn't have these diodes.
Given that NT has a rather poor grasp of the subject, his lack of success isn't really surprising.
--
Bill Sloman, Sydney
If you look at a PV array's v/i curve without thinking about what's actually going on you can probably duplicate NT's mistake.
> I don't know what %age of PV arrays have diodes to work around this, but the ones I've tried this with did not do well, so I expect they didn't have these diodes.
Given that NT has a rather poor grasp of the subject, his lack of success isn't really surprising.
--
Bill Sloman, Sydney
B
Bill Sloman
Guest
On Wednesday, October 16, 2019 at 11:57:38 PM UTC+11, Jeroen Belleman wrote:
And not all the photocurrent comes out of the terminals - some biases the diode.
There's an optimal bias that trades off the extra bias you can get with a smaller current at a higher bias against the extra current you get at a lower bias.
But the "leakage" current that has to flow to sustain the diode bias voltage is subtracted from the photo curren tyou can exploit.
You can arrange photovoltaic cells in a PV panel any way you like.
https://www.solarreviews.com/blog/do-you-wire-solar-panels-series-or-parallel
If you can make cheap micro-inverters parallel would work better.
Not necessarily. Within limits, the highly illuminated cells will produce more photo current, but use more of it to generate a higher bias voltage, so that they deliver the same current through the string as the less well-illuminated cells that will deliver a higher proportion of their photo current while using less of it to sustain a lower bias voltage across the cell.
Neither of them will be operating at their optimal power generation bias, but they won't be far off it.
If it is wired in series, which is a matter of choice.
As with all technical questions, the answer is complicated and the audience inclined to ignore complications. Detailed consideration always looks like nit-picking, particularly to people who have made up their minds prematurely.
--
Bill Sloman, Sydney
And not all the photocurrent comes out of the terminals - some biases the diode.
There's an optimal bias that trades off the extra bias you can get with a smaller current at a higher bias against the extra current you get at a lower bias.
But the "leakage" current that has to flow to sustain the diode bias voltage is subtracted from the photo curren tyou can exploit.
You can arrange photovoltaic cells in a PV panel any way you like.
https://www.solarreviews.com/blog/do-you-wire-solar-panels-series-or-parallel
If you can make cheap micro-inverters parallel would work better.
Not necessarily. Within limits, the highly illuminated cells will produce more photo current, but use more of it to generate a higher bias voltage, so that they deliver the same current through the string as the less well-illuminated cells that will deliver a higher proportion of their photo current while using less of it to sustain a lower bias voltage across the cell.
Neither of them will be operating at their optimal power generation bias, but they won't be far off it.
If it is wired in series, which is a matter of choice.
As with all technical questions, the answer is complicated and the audience inclined to ignore complications. Detailed consideration always looks like nit-picking, particularly to people who have made up their minds prematurely.
--
Bill Sloman, Sydney
R
Rick C
Guest
On Tuesday, October 15, 2019 at 3:41:26 AM UTC-4, Tom Gardner wrote:
I guess I have no idea what you mean by, "use the energy in the light for photosynthesis or electricity; make your choice" because my point is you don't need to optimize anything to capture every last bit of light. I guess you just aren't grasping what I'm saying. By leaving space between the rows it maximized the utility of the solar cells for receiving the direct sunlight, while leaving un-captured light to fall between the rows. By "un-captured light" I mean the light from parts of the sky that are not direct sun light.
Ok, you seem to be intentionally ignoring the meaning of my words.
"other than selected species"
What do you think I meant by that???
Not intended to be an insult. It is a summary of everything you have told me. I believe it was you who tried very hard to impress upon me the density of housing, the crowding, the lack of adequate parking on top of the lack of adequate electrical infrastructure as well as the lack of generation capacity in the UK. I am simply agreeing with the obvious, that the UK is in such bad shape it will take a ginormous effort for them to accommodate EVs and many forms of renewable energy.
I think one of us doesn't understand the meaning of alt-right.
No prejudice and it is YOU who has educated me regarding the UK and energy. Thank you for the education.
Yes, I'm sure the coal generation will never be missed... unless it is. What did the cause of the recent black out turn out to be when all the dust settled? I seem to recall it had to do with a couple of hundred MW of fossil fuel generation going off line. How will the country cope with losing ALL the coal generation? I guess Hinkley will supplant that... except it won't be online until 2025 and even then only if you believe the latest schedule.
I guess they will need to find a way to install a bunch of renewables... really???
--
Rick C.
---- Get 2,000 miles of free Supercharging
---- Tesla referral code - https://ts.la/richard11209
On 15/10/19 05:32, Rick C wrote:
On Monday, October 14, 2019 at 6:09:39 AM UTC-4, Tom Gardner wrote:
On 14/10/19 09:33, Rick C wrote:
On Monday, October 14, 2019 at 4:05:02 AM UTC-4, Tom Gardner wrote:
And so we are back to my earlier (unoriginal[1]) point: basically you
can use the energy in the light for photosynthesis or electricity;
make your choice
I already replied to that point didn't I?
Yes. You had no answer.
For some reason you *deliberately* snipped your reply and *chose* to make
it difficult to assess. Here it is again...
You are getting your posts confused...
This is what your posted and my reply...
Basically you can use the energy in the light for photosynthesis or
electricity; make your choice
Solar cells are optimized by assuring they receive direct light from the sun
as much as possible. Land is not the quantity to be optimized in most
installations, so you will want to leave space between rows to prevent one
row shading the other. This naturally will leave some land not covered with
solar cells and will receive diffuse light from other parts of the sky.
Grass won't grow great, but it will grow. Not sure it will be robust enough
for animals to graze on. I know sheep grazing messes up the grass because
they don't cut it, they pull it up by the roots. Cows not so much. Cows
like to rub against things and will knock over anything that isn't pretty
firmly in the ground, like fences.
So, we agree. Good. Let's move on.
I guess I have no idea what you mean by, "use the energy in the light for photosynthesis or electricity; make your choice" because my point is you don't need to optimize anything to capture every last bit of light. I guess you just aren't grasping what I'm saying. By leaving space between the rows it maximized the utility of the solar cells for receiving the direct sunlight, while leaving un-captured light to fall between the rows. By "un-captured light" I mean the light from parts of the sky that are not direct sun light.
Ok, you seem to be intentionally ignoring the meaning of my words.
"other than selected species"
What do you think I meant by that???
Not intended to be an insult. It is a summary of everything you have told me. I believe it was you who tried very hard to impress upon me the density of housing, the crowding, the lack of adequate parking on top of the lack of adequate electrical infrastructure as well as the lack of generation capacity in the UK. I am simply agreeing with the obvious, that the UK is in such bad shape it will take a ginormous effort for them to accommodate EVs and many forms of renewable energy.
I think one of us doesn't understand the meaning of alt-right.
No prejudice and it is YOU who has educated me regarding the UK and energy. Thank you for the education.
Yes, I'm sure the coal generation will never be missed... unless it is. What did the cause of the recent black out turn out to be when all the dust settled? I seem to recall it had to do with a couple of hundred MW of fossil fuel generation going off line. How will the country cope with losing ALL the coal generation? I guess Hinkley will supplant that... except it won't be online until 2025 and even then only if you believe the latest schedule.
I guess they will need to find a way to install a bunch of renewables... really???
--
Rick C.
---- Get 2,000 miles of free Supercharging
---- Tesla referral code - https://ts.la/richard11209
T
Tom Gardner
Guest
On 17/10/19 06:55, Rick C wrote:
More ignorant "guesses", which you could easily have checked but
chose not to. I leave others to assess why you chose those particular
inaccurate "guesses".
Firstly the power source was irrelevant; what mattered was
that a source, *any source*, went offline unexpectedly.
The cause was a lightning strike.
That took 737MW from Hornsea *windfarm* off line.
Then 885MW from Little Barford gas station went offline.
So your statement is /false/ in /every/ important respect.
More ignorant "guesses", which you could easily have checked but
chose not to. I leave others to assess why you chose those particular
inaccurate "guesses".
Firstly the power source was irrelevant; what mattered was
that a source, *any source*, went offline unexpectedly.
The cause was a lightning strike.
That took 737MW from Hornsea *windfarm* off line.
Then 885MW from Little Barford gas station went offline.
So your statement is /false/ in /every/ important respect.
R
Rick C
Guest
On Thursday, October 17, 2019 at 2:53:49 AM UTC-4, Tom Gardner wrote:
Nothing you have said is even relevant. The issue is that the UK grid is friable, fragile, brittle, delicate. Then you talk about how they plan to retire GWs of coal based generation BEFORE they can bring up the nuclear generators at Hinkley.
Besides, what I wrote wasn't wrong. Read it again. Or better, don't. You clearly are wound up regarding this issue. Just give it a rest. You'll feel better.
--
Rick C.
---+ Get 2,000 miles of free Supercharging
---+ Tesla referral code - https://ts.la/richard11209
Nothing you have said is even relevant. The issue is that the UK grid is friable, fragile, brittle, delicate. Then you talk about how they plan to retire GWs of coal based generation BEFORE they can bring up the nuclear generators at Hinkley.
Besides, what I wrote wasn't wrong. Read it again. Or better, don't. You clearly are wound up regarding this issue. Just give it a rest. You'll feel better.
--
Rick C.
---+ Get 2,000 miles of free Supercharging
---+ Tesla referral code - https://ts.la/richard11209