Posted by Scottish Scientist on July 6, 2019, 6:33 pm
Wind, solar, storage and back-up system designer for 100% renewable energy
grids and microgrids with 24/7/52 power-on-demand!
Replies, comments and questions about using the Wind, solar, storage and ba
ck-up system designer at this blog link please.
Peak demand, wind, solar and back-up power / energy usage and storage capac
For the specification and design of renewable energy electricity generation
systems which successfully smooth intermittent wind and solar generation t
o serve customer demand, 24 hours a day, 7 days a week and 52 weeks a year.
Adopting the recommendation derived from scientific computer modelling, the
tables offer rows of previously successful modelled system configurations
– row A, a configuration with no back-up power and rows B to H offe
ring alternative ratios of wind and solar power to back-up power.
The recommended energy storage capacity is about 90% of one day’s a
verage wind and solar energy generation.
The tables’ columns consist of power and energy variables.
A cell value can be adjusted according to the design criteria and then all
the other table values will be recalculated, spreadsheet-style.
The wind and solar power generation Capacity Factor (C.F.) percentages can
be adjusted too.
The energy generation percentages from wind and solar power can be adjusted
, either directly or according to the latitude of the system.
A configuration text page for a row which has been adjusted and designed sa
tisfactorily can be opened for text output by clicking on the row’s
“TXT” icon in the “Open text page” column.
The recommendations derived from modelling are only specified to 2 signific
ant figures so take with a pinch of salt any apparently third “sign
ificant” figures in the numbers output in the configuration text pa
My 100% Renewable Energy Blog
Posted by ads on July 6, 2019, 9:12 pm
On Sat, 6 Jul 2019 11:33:13 -0700 (PDT), Scottish Scientist
You obviously haven't considered the rest of the world. There are
some places which simply DO NOT HAVE USEFUL WIND.
Back to the drawing board for you.
Posted by Jim Wilkins on July 6, 2019, 11:28 pm
<ads> wrote in message
Where I live in New Hampshire, USA the average wind is under 10 kts,
wood stove smoke often rises vertically. Temps run from -20C in winter
(-40C,F in northern NH) to the mid to upper 30's C / high 90's to 100F
Today's high was 34C and the dewpoint is presently at 24C, which is
tropically miserable, and this is the cooler northern edge of the USA.
It's hard to do without at least a window air conditioner. Mine, the
smallest commonly available, draws 350 Watts for about 4 - 6 hours a
night during heat waves. The starting surge is too much for my sine
inverter so it has to run on grid or generator power. I haven't seen a
Danfoss/Secomp type air conditioner for sale here though I have a
We can easily have a week of thick overcast that drops my solar panel
output to less than 10% of capacity. Under these conditions, and
considering the cost of battery depreciation with cycling or just age,
solar power doesn't quite break even.
I pay USD $.18 per KWH for grid power. If my $20, 12V, 105Ah
batteries meet the maker's 500 cycle lifetime spec they raise the cost
of "free" solar electricity to ~$.20 per KWH. Shallower discharges
require more batteries and per the charts I've seen don't increase the
total number of KWH stored and delivered over the battery's lifetime.
I haven't considered cheaper used batteries here because my sources
for them are uncertain and their condition has proven too variable.
Posted by Scottish Scientist on July 7, 2019, 2:52 am
On Sunday, 7 July 2019 00:27:15 UTC+1, Jim Wilkins wrote:
"10 kts" is 5.1 metres per second right?
This shows some places with a higher wind average speed than that.
New Hampshire 80-Meter Wind Resource Map
The trick is to build the wind farms where it is windiest and transmit the electrical power to customers via the grid.
I've seen maps showing that it is much windier in winter in New Hampshire - so the wind power would be most useful for heating in the winter whereas solar can help with the air conditioning in summer.
(Continued later after I have had a good night's sleep).
Posted by Jim Wilkins on July 7, 2019, 12:51 pm
This state makes good use of alternate sources including micro hydro,
several productive wind farms and wood-fueled electric generators. I'm
in a forest of 80~100' oaks on the downwind side of a ridge. The site
provides plentiful free firewood and logs for my home made sawmill but
little wind and restricted sun. To use my solar panels effectively I
have to set them on the lawn and move them to dodge tree shadows, so
they are only good for tests and emergency power outages which can
last a week here in summer hurricane and winter ice storm country.
Their folding support legs are Vs made from electrical conduit.
These can be used for an inexpensive DIY datalogger for alternate
The optical isolation avoids common mode (and short circuit) problems
between voltage and current channels and the batteries can be
rechargeable AAs. I use an old laptop with added serial port cards to
read them because it runs on low power DC and I can read the COM ports
but not USB in DOS/QBasic programs, thus avoiding Windows port polling
interference and allowing me to use all bits of the parallel port for
digital I/O. There are also USB versions of the meters if you don't
want to program control outputs. The separate datalog files can be
combined in a spreadsheet by aligning the timestamps.
I think the meters are better suited to PWM than MPPT controllers. The
panel output, controller output and battery in/out power meters don't
agree very well when running the MPPT.
Grid-tied solar without batteries is common here but stand-alone
systems like I built appear to be practical for daily use only in
remote locations. DC-powered refrigerators for them are either very
expensive or of questionable reliability, like my Alpicool.
It does have the advantage of not needing a pure sine inverter
constantly drawing on the battery.