Posted by Jim Wilkins on July 9, 2019, 11:55 am
> ...
> If for technology reasons, you want a lower discharge percentage
> then add batteries to suit your supplier recommendations for maximum
> discharge.
> ...
It seems to me that your elegant html script (which I examined) is
directed toward helping managers or accountants estimate the scope and
cost of a project, rather than an engineering design tool.
A user who can make the technical adjustments you've suggested could
likely analyze, specify and design the system themselves.
Posted by Jim Wilkins on July 9, 2019, 12:17 pm
>> ...
>> If for technology reasons, you want a lower discharge percentage
>> then add batteries to suit your supplier recommendations for
>> maximum discharge.
>> ...
>
> It seems to me that your elegant html script (which I examined) is
> directed toward helping managers or accountants estimate the scope
> and cost of a project, rather than an engineering design tool.
>
> A user who can make the technical adjustments you've suggested could
> likely analyze, specify and design the system themselves.
>
Please understand that, as I just posted to another group, I read and
post here when I'm too sleepy or tired for the real work, which
presently is running a sawmill and moving the logs and cut timbers by
hand.
Posted by ads on July 9, 2019, 9:50 pm
On Tue, 9 Jul 2019 07:55:28 -0400, "Jim Wilkins"
>> ...
>> If for technology reasons, you want a lower discharge percentage
>> then add batteries to suit your supplier recommendations for maximum
>> discharge.
>> ...
>
>It seems to me that your elegant html script (which I examined) is
>directed toward helping managers or accountants estimate the scope and
>cost of a project, rather than an engineering design tool.
>
>A user who can make the technical adjustments you've suggested could
>likely analyze, specify and design the system themselves.
>
And said person would have to quote chapter and verse to keep the
managers and accountants from Hell from buying into the
"scientifically" designed system in a big way - or just refute all the
errors/omissions, using practical manufacturers' specifications such
as www.renogy.com/calculators and practical planners such as those at
nrel.gov to support the white paper and get it dated and filed in the
corporate document system early enough that it *could* have prevented
the "I don't understand why that didn't work. It cost us X million
dollars/pounds/euros and the rain only lasted three days." type
failure.
Any planning tool needs to have its limitations specified in the first
sentence. Even the documenting of my solar generator - something that
few will ever see - starts off with:
"This is not a neatly organized description of what I've built or a
plan for building your own solar generator. It's a (slightly) cleaned
up collection of notes made as I did the design and collected parts to
build a solar generator for my own use."
The associated spreadsheets similarly have about as much in text notes
as in computations.
Posted by Jim Wilkins on July 9, 2019, 11:48 pm
<ads> wrote in message
> On Tue, 9 Jul 2019 07:55:28 -0400, "Jim Wilkins"
>
>>...
>>A user who can make the technical adjustments you've suggested could
>>likely analyze, specify and design the system themselves.
>>
>
> And said person would have to quote chapter and verse to keep the
> managers and accountants from Hell from buying into the
> "scientifically" designed system in a big way - or just refute all
> the
> errors/omissions, using practical manufacturers' specifications such
> as www.renogy.com/calculators and practical planners such as those
> at
> nrel.gov to support the white paper and get it dated and filed in
> the
> corporate document system early enough that it *could* have
> prevented
> the "I don't understand why that didn't work. It cost us X million
> dollars/pounds/euros and the rain only lasted three days." type
> failure.
> ...
I was fortunate/careful to avoid that, even on major FAA and Air Force
contracts. The Ph.D project manager pushed his proposal through, then
came to my lab with datasheets for the weirder components and a
scribbled block diagram and asked if I could build it. They quickly
learned they could safely leave me alone until I turned in the
finished schematic, then usually skip the design review and tell me to
continue with the circuit board and packaging.
I didn't have the SPICE simulation tools to design microwave patch
antennas or impedance matching stubs so they helped with those parts.
25 years later similar devices cost $00 at hamfests instead of
$0,000.
https://www.sdrplay.com/
I did have a simulator for Xilinx configurable logic arrays. That's an
amazing piece of tech, you think up a circuit, draw it, then compile
and load the device with a file that configures it to become the
schematic, like 3D printing an electronic circuit. I can turn ideas
into metal too, but they have to pass through the lathe and milling
machine.
Posted by Scottish Scientist on July 8, 2019, 3:29 pm
On Monday, 8 July 2019 04:21:21 UTC+1, ads wrote:
> On Sun, 7 Jul 2019 16:34:14 -0700 (PDT), Scottish Scientist
>
> >On Sunday, 7 July 2019 22:50:11 UTC+1, ads wrote:
> >
>
> >Breaks my heart to design you a system that generates so little power. ;
) LOL.
>
> Some questions for you:
>
> How far do you plan on discharging those batteries?
>
> How many days of little or no sun do your calculations include?
>
> I know that we can easily have a week or more of cloudy, rainy days in
> winter and my best solar panel only produces about 5% of its rated
> output on a rainy day.
>
> The past two weeks, we've had summer thunderstorms almost daily, with
> there being less than 50% of "normal" sun most of those days.
Thank you for your on-topic questions Ads.
> How far do you plan on discharging those batteries?
There's the off-grid table for 4KWh maximum daily usage and 8% solar capaci
ty factor.
http://scottish.scienceontheweb.net/Wind%20power%20storage%20back-up%20calc
ulator.htm?usage=4&units=kw&spc0&scf=8#off
Here's the text configuration page for row D.
Wind, solar, storage and back-up system designer
- hide quoted text -
Configuration text page.
Daily Usage of Energy: 4 KWh
Solar Power Capacity: 2.64 KW
Solar Capacity Factor: 8%
Solar energy per day (average): 5.07 KWh
Storage Energy Capacity: 4.48 KWh
Back-up power: 0.093 KW
So 3KW of solar panels, 4 of your 12V105Ah batteries and a 100 Watt generat
or if you can find one that small, would do that, if that's all you need to
get you through your power outages?
The configuration species "Storage Energy Capacity: 4.48 KWh" but it doesn'
t specify "batteries" or "pumped storage" or "power to gas".
The numbers in the designer are technology neutral.
The numbers don't take account of any safety margin for the particular tech
nology, so you have to add that yourself.
"4 of your 12V105Ah batteries", taking the name-plate at face value, would
offer 4 x 12V x 105A h = 5.04 KWh of energy storage.
So I suppose, since you are asking, that would amount to 4.48/5.04 - 89% di
scharge if you started with a fully charged battery and used up 4.48 KWh th
at the designer specifies.
If for technology reasons, you want a lower discharge percentage then add b
atteries to suit your supplier recommendations for maximum discharge.
> How many days of little or no sun do your calculations include?
The designer depends on the average daily energy value (that's the column h
eaded "Wind + Solar *Wh per day", in the Off-grid daily usage) being about
right for that time of year.
So in the case of 100% solar or mainly solar powered systems in parts of th
e world that have significant seasonal solar power variation, I would recom
mend to to use a seasonal or monthly solar capacity factor or even a monthl
y solar capacity factor. If designing a system for all-year round then pick
a winter solar factor.
Beware that if you are designing using a yearly solar capacity factor then
the system may be underpowered in winter.
In the example, I quoted to Jim, I made explicit that I was designing for s
ummer and used an assumed solar capacity factor.
"Let's just assume that a New Hampshire residential utility customer's maxi
mum daily usage was worked out to be 40 KiloWatt-Hours and for that max usa
ge the customer wanted to construct a solar power system to supply that pow
er in the summer.
So for that customer requirement, the Wind, solar, storage and back-up syst
em designer, "Off-grid daily usage Focus Table" can be seen at this link.
http://scottish.scienceontheweb.net/Wind%20power%20storage%20back-up%20calc
ulator.htm?usage@&units=kw&spc0&scf#off
As you can see, I have assumed a solar capacity factor for the New Hampshir
e summer of 16% - but that's just my guess. You would need to research your
own solar capacity factor for yourself. "
If you need a system that performs well in both winter and solar then you n
eed to mix up your generation sources in winter, wind, biofuels, hydroelect
ric hydrogen from power to gas etc.
I appreciate that for home owners they don't have the wide choice of genera
tors that states do so home powered systems may not have good renewable ene
rgy winter generating options.
Wind is probably the best bet for reliable winter power, if you can get per
mission to put up a wind turbine or two near by.
In all cases the designer page is going to give the best results if you kno
w what your local solar and wind capacity factors are.
> If for technology reasons, you want a lower discharge percentage
> then add batteries to suit your supplier recommendations for maximum
> discharge.
> ...