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so welcome to the um C communication
Camp 23 again this is the bits and Bo
stage and um we have um the next talk
happening over here about um open
hardware and uh solar energy and um open
mptt
project and um for that I would like to
welcome the Electra wagon rod correct
from correct Berlin who is active in the
local fun Community for a long time
there and 20 years 20 years and we will
have some short Q&A in the end um the
talk is 20 minutes is in English there's
no German translation
sorry thank you very much thank you very
much for
coming so as this is a short talk and I
have 16 slides um it also comes down to
what you know about the project so it's
an open software and open Hardware
project that you should be able to build
yourself around the planet and it should
help you in many situations where you
need independence from energy it started
in
2017 during the time when frun was
supporting refugees in the refugee
crisis where people were living in
informal camps
and they had no electricity and they had
no communication basically so we were
thinking how can we bring to informal
refugee camps in the field somewhere
solar powered energy and solar powered
connectivity we were mostly concerned
about the
connectivity setting up independent
wireless
routers that's how it started in
2017 and the project has evolved quite a
lot there's no three different
devices that I have engineered over time
so it started in 2017 mark one it is a
50 wat Peak maximum PowerPoint tracker
who of you does not know what a maximum
PowerPoint tracker
does all right I will be brief but it's
a complex subject to explain if you run
a solar
module you have a certain voltage where
the module creates the most power where
the power output of the solar generator
is the most
efficient if you connect it to a battery
in an autonomous system without a
maximum PowerPoint tracker in between
the battery will just suck down the
generator to the voltage of the battery
while it is charging which means for
example you have a panel that produces
30 volts at maximum power and you
connect it to a 12vt battery and then
the voltage in the solar panel drops
down to the level of the battery so and
the current amazingly stays almost the
same so if you could Harvest 30 volts
and 1 ampere you will harvest 12 volts
and 1 Point a tiny bit of little a
little more amps so will you will lose a
lot of the power and a maximum power Co
tracker can help this it can can detect
at which voltage the generator is the
most happy and can produce the most
power and then it uses a step down
converter in my case and tracks the
voltage of the solar panel so it stays
in that maximum PowerPoint and then
transforms it down to the level of the
battery and the result is that the
current that charges the battery is
increasing like in a 30 volt panel it
can be more than double the current that
comes from the solar panel
so what you see here is Mark one
actually the first prototype I've edged
it myself and uh you of course you can
find the files on the internet and it
actually if you have a workshop and you
know how to Edge
pcbs then you can Edge it yourself you
need a drill and a soldering iron into
components you download the files you
print them on a laser printer you use
them to expose it to S photo sens stied
PCB
material and you can add it yourself or
you just order pcbs from a
manufacturer so Mark 1 was designed to
use in to be used in combination with a
wireless router running open
WT the idea was to make the smallest and
cheapest solar node that is energy
autonomous for an entire year in the
area of Berlin for example
and you can monitor it from afar so you
deploy it
somewhere and you can connect to that
opal WT based router and you can read
the data from the maximum PowerPoint
tracker you can check the charge of the
battery and so
on in
2018 um three people including me we
were um we got a grant from the prototyp
type Fund in their third round so we
could work on a web app and other
software
in uh open WT Lua programs to do this
monitoring and data
aggregation and uh that program needed a
name so it was called isims independent
solar energy mesh
system so this is how we figured out
would be a good way for such a mobile
Disaster Recovery node a solar panel at
the ground a telescopic M and on top a
waterproof router with Wi-Fi and mesh
capability on the right side you see a
little screenshot from the
app and it shows you the situation of
that node it's a note on the roof of of
my Hut and it's just showing the system
is fine it is supposed to give
information that even if you're not too
technically skilled you learn something
about the health of your
system and then came Mark 2 I thought to
further reduce the cost for some
situations for example you live in a
village that is cut off from the
internet pretty
much and there's Hill in between you and
another place where you can get internet
from via
Wireless you could use a device that is
based on the ESP 32 chip that has Wi-Fi
on board as a Wi-Fi relay so it became
optional to add that open WT based
router
because the second generation became
self-sufficient with regards to Wi-Fi it
cannot do completely mhet workk
working it can do as uh routing
now but it doesn't need the extra power
to power an open WT based router and it
still gives you some megabytes per
second in relaying traffic between two
places if the RF signal is strong
enough are you
okay I hope I'm not boring you at
[Laughter]
all so and then people came and said
well that ESP 32 chip that has the Wi-Fi
on board it has many unused
gpios please why don't you expose these
we could use it for sensors and for
whatnot and people were asking hey why
do you only want to power wireless
routers we need more power give us more
power which was out of the scope of what
I in initially intended to do with this
project but I said okay well it opens up
the possibility to use it for other
things as well
sensors you we'll see a few examples
later why not so I extended the design
added one more pin header and increased
the power I doubled it
basically but this wasn't the end
because people were saying why only 100
what Peak we need more
power initially I had thought okay there
is commercial maximum PowerPoint
trackers on the market that you can buy
from companies I don't mention those
companies but of course there's a virtue
in having an open source and open
Hardware project that you can extend and
hack
on the devices since I use the
esp32 you can tell it into the machines
sorry no SSH but you can tell that into
the machine you can FTP programs into
the machine or download it from
there you have of course a website you
have a web interface you have mqtt
protocol as a
Telemetry you can configure it that it
sends to two mqtt servers its data so
you can monitor it from everywhere and
you can run your own server to monitor
it
locally and of course since the device
now expanded to yeah a device you can
also use stationary I also added the
option to have a display in the 3D
printed housing so you can also 3D print
your
housing but please use flame retardant
PG because it's strong Electronics High
currents in the worst case when you have
like full power from the Sun coming in
and full power demanded from the battery
it can deliver up to 50 amp to your
consumers so that's a current you can
use for welding yeah and the peak
currents inside the device they can go
to 30 amp at 400 wats
Peak so that's why you see this massive
inductor coil which is used as the
Transformer prototype number
two uh of this device has been tried in
an experiment in antill in India because
what can you do with 400 wats Peak solar
power you can run a small server and
have a community that doesn't have
internet access and give them local
services like local Wikipedia local
video streaming and
whatnot so this is another nice addition
uh the software running on the Fring
Center is Nimble is another project I
don't know if Eric who is involved the
project is
around two pictures of India from India
and also pictures that I use I'm going
to use in the printed documentation uh
how not to use the
device the people in anill they have
built a bamboo Tower with a metal
housing where the sun is blaring on That
Metal
housing and they have put the
batteries into the metal housing to make
theft of the batteries more difficult
but the same time they are frying the
batteries and they're also frying my
electronics the device is supposed to be
mounted upright so you have some air
cool Airstream to cool that powerful
inductor because at full power only the
inductor can produce 5 watts of heat and
that heat has to go somewhere it's not
supposed to be accumulated in that
housing and then people came again and
said you
know why not build a device for watering
plants
independently so I built a prototype
based on the 100 watt version for
irrigation so it measures humidity of
the
soil it controls water valves
it controls a pump to provide water to
the system and it also has a tank gge to
measure the amount of water that is
remaining in the tank and of course it
sends everything via mqtt protocol to
the service you like so you can monitor
it I think this is quite helpful at the
moment it's a prototype made with wiring
on an existing device but I consider
also making a PCB for this purpose
just um yeah in uh last Autumn I took
these these pictures that's these are
these uh drop
irrigation uh yeah Outlets um you can
save a lot of water and you can treat
your plants really well with this um I
learned I'm not too much into gardening
that you should water your plants about
one hour before the sun goes up in the
morning
that's the best time where you avoid A
fungi growing on your plants and the
water is used most effectively and in
times of draw yeah that might be a
really good
thing so I promised not to talk too much
and spend too much time so I thank you
for your
interest and now we're ready for
questions and
answers
[Applause]
so we have some questions so raise your
hand that we can see you and then we try
to accommodate as many as we can in 5
minutes hi um are the design files or
the schematics for the mark 2 or Mark
III uh available anywhere Mark Mark is
available at electra. info and then you
go to the site and you go to FF
esp32 um I have not published markree
because I'm not completely done with the
development
yet and if you want to produce them
please uh contact me for the latest
files and also the support with some of
the components because and yeah the chip
crisis and well you know the resource
crisis also hit me I'm still waiting for
some power inductors for like 2 months
now over there to the back yes if you if
you raise your hands a little bit
earlier we can like be prepared to where
we need
to on a appear after like I have to talk
because it's a long way for the
microphone to reach the next question
and there we
go hi um first of all thank you for all
of this uh I have a good idea about what
in uh MPP tracker is doing but I have no
clue how it's been done how how is it
how it is doing it could you maybe
elaborate a bit on on the implementation
and how you specifically achieve this um
do you know what the dcdc bu converter
does and how it works so basically you
have in a standard dcdc bu converter you
have a feedback loop that controls the
output and there's just yet another
feedback loop which is controlling the
input
so the pulsewidth modulation is
controlled by the voltage at the input
and finally when you reach the charge
end level at the
output so because a standard bu
converter you can try this without such
an outer feedback control Loop it will
just try to suck as much current as it
get and then you still have the same
effect like well it's even worse than
just connecting your battery to the
solar panel without dcdc bule in between
other than that of course it's a solar
controller as well so it protects your
battery from overcharging and deep
discharging which would damage the
batteries oh but I forgot to mention um
so far I have been using AGM lead
batteries but I'm at the moment I'm
working on Leaf po so Leaf lithium iron
phosphate batteries and yeah and modify
the charge controller for this in the
software I don't need to do anything in
the
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hardware and any questions more question
I see this guy over there yes
it's um what is the voltage for the
batteries can you configure it and in
which
range it's a very good question no at
the moment I it's 12 volts so you can
charge up to 14.7 volts and you can
control it from software so use the
chemistry you like um if I would make
some changes for like 24 volt systems
then the the power capacity would double
also but um I'm personally using systems
like these and I prefer having like a
single 12vt battery rather than have
several in a row but I know many people
are saying H well why not get 24 or 36
or 48 volt but at one point I'm going to
do it probably and of course the
challenge for people asking hey
why only 400 wats it
continues
numbers
okay anyone else I have otherwise I
would have a last question then but go
oh say tell if it's sorry I would repeat
it otherwise one very short question
about the autonomy of your project in
berin you told you can reach about 100%
of autonomy uh which calculator did you
use for that
assumption oh there is a there's a
manual when you go to the Electra site
there is a big man is like 52 pages and
uh I'm trying to cover well not
everything but as much as I can and I
like a printed documentation of course
it's a PDF you can print it out whatever
maybe I'll publish it as a book and
people can buy it to support
me you know um sorry I I'm I'm
lost um say it again C the calculator
the calculator um I used uh there is
some some Global uh irrigation
calculator and um a very conservative
estimate of this of the storage for um
for these dark times you know the yeah
but it might you know the weather
changes if if there is like three weeks
of of absolutely no sunshine where the
cars drive at noon with the lights on
then of course it could
happen so I cannot guarantee
100% And okay so I have also a question
so commercial mppts um are available of
course but they are quite expensive too
um and if I want to use it with like um
low power um solar batteries that I get
of them from from secondhand Market or
something it's not really feasible so
how much is an invest to build um open m
PTT or or like cheaply you mean the
biggest one or or just you pick the size
that you you
want when you build it on your own the
question is how many of are you going to
build are you just building one or a
few um I think if you order them in
China you know you can have them made in
China companies like don't mention um
then it's fairly cheap um but of course
you have to do some assembly they
wouldn't do through through hole
assemblies and you have to do some
initial programming and so on probably
for the 100 wat version maybe
35 all in
all thank you thank you very much thank
you very much and that's our
time thank you thank
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you