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Wind, solar, storage and back-up system designer - Page 8

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Posted by Jim Wilkins on July 9, 2019, 11:55 am

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

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  

Posted by ads on July 9, 2019, 9:50 pm
 On Tue, 9 Jul 2019 07:55:28 -0400, "Jim Wilkins"

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

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  

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  

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  

Posted by Scottish Scientist on July 8, 2019, 3:29 pm
On Monday, 8 July 2019 04:21:21 UTC+1, ads  wrote:

) LOL.  

Thank you for your on-topic questions Ads.  

There's the off-grid table for 4KWh maximum daily usage and 8% solar capaci
ty factor.  

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.

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.


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.

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