camp2023-57058-eng-Resilient_solar_energy-autonomous_infrastructure_with_Freifunk-OpenMPPT_controllers_opus.srt

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 [MUSIC]

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 So

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 welcome to the Chaos Communication Camp 23.

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 Again, this is the Bitz and Boimer stage.

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 And we have the next talk happening over here

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 about open hardware and solar energy and open MPT project.

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 And for that, I would like to welcome the Elektrowagenrat.

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 >> Correct, that's correct.

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 >> From Berlin, who is active in the local Freifunk community for

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 a long time there and- >> 20 years.

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 >> 20 years, and we will have some short Q&A in the end.

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 The talk is 20 minutes.

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 It's in English, there's no German translation, sorry.

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 >> [APPLAUSE]

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 >> Thank you very much.

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 Thank you very much for coming.

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 So as this is a short talk and I have 16 slides,

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 it also comes down to what you know about the project.

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 So it's an open software and open hardware project that

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 you should be able to build yourself around the planet.

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 And it should help you in many situations where you need

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 independence from energy.

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 It started in 2017, during the time when Freifunk was supporting refugees,

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 in the refugee crisis, where people were living in informal camps.

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 And they had no electricity and they had no communication basically.

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 So we were thinking, how can we bring to informal refugee camps in the field

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 somewhere solar powered energy and solar powered connectivity.

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 We were mostly concerned about the connectivity,

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 setting up independent wireless routers.

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 That's how it started in 2017 and the project has evolved quite a lot.

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 There's now three different devices that I have engineered over time.

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 So it started in 2017, Mark 1.

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 It is a 50 watt peak maximum power point tracker.

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 Who of you does not know what a maximum power point tracker does?

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 All right, I will be brief, but it's a complex subject to explain.

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 If you run a solar module, you have a certain voltage where the module

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 creates the most power, where the power output of the solar

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 generator is the most efficient.

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 If you connect it to a battery in an autonomous system,

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 without a maximum power point tracker in between, the battery will just suck

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 down the generator to the voltage of the battery while it is charging.

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 Which means, for example, you have a panel that produces 30 volts at maximum power.

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 And you connect it to a 12 volt battery and then the voltage in the solar panel

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 drops down to the level of the battery.

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 And the current amazingly stays almost the same.

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 So if you could harvest 30 volts and one ampere, you will harvest 12 volts and

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 one point a tiny bit of little more amperes.

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 So you will lose a lot of the power.

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 And a maximum power point tracker can help this.

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 It can detect at which voltage the generator is the most happy and

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 can produce the most power.

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 And then it uses a step down converter, in my case, and

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 tracks the voltage of the solar panel so it stays in that maximum power point.

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 And then transforms it down to the level of the battery.

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 And the result is that the current that charges the battery is increasing.

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 Like in a 30 volt panel,

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 it can be more than double the current that comes from the solar panel.

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 So what you see here is Mark 1, actually the first prototype.

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 I've etched it myself and of course you can find the files on the internet.

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 And actually if you have a workshop and you know how to etch PCBs,

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 then you can etch it yourself.

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 You need a drill and a soldering iron and the components.

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 You download the files.

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 You print them on a laser printer.

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 You use them to expose it to photosensitized PCB material.

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 And you can etch it yourself.

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 Or you just order PCBs from a manufacturer.

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 So Mark 1 was designed to be used in combination with a wireless router

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 running OpenWRT.

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 The idea was to make the smallest and cheapest solar node

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 that is energy autonomous for an entire year in the area of Berlin, for example.

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 And you can monitor it from afar.

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 So you deploy it somewhere and you can connect to that OpenWRT based router.

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 And you can read the data from the maximum power point tracker.

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 You can check the charge of the battery and so on.

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 In 2018, three people including me,

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 we got a grant from the prototype fund in their third round.

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 So we could work on a web app and

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 other software in OpenWRT, Lua programs,

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 to do this monitoring and data aggregation.

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 And that program needed a name, so it was called iSIMS,

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 Independent Solar Energy Mesh System.

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 So this is how we figured out would be a good way for

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 such a mobile disaster recovery node.

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 A solar panel at the ground, a telescopic mast, and

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 on top a waterproof router with Wi-Fi and mesh capability.

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 On the right side you see a little screenshot from the app.

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 And it shows you the situation of that node.

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 It's a node on the roof of my hut.

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 And it's just showing the system is fine.

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 It is supposed to give information that even if you're not too

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 technically skilled, you learn something about the health of your system.

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 And then came Mark II.

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 I thought to further reduce the cost for some situations.

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 For example, you live in a village that is cut off from the internet pretty much.

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 And there's a hill between you and

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 another place where you can get internet from via wireless.

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 You could use a device that is based on the ESP32 chip that has Wi-Fi on board.

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 As a Wi-Fi relay.

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 So it became optional to add that open WT based router because

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 the second generation became self-sufficient with regards to Wi-Fi.

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 It cannot do completely mesh networking.

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 It can do routing now.

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 But it doesn't need the extra power to power an open WT based router.

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 And it still gives you some megabytes per second in relaying traffic between

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 two places if the RF signal is strong enough.

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 Are you okay?

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 [LAUGH]

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 I hope I'm not boring you at all.

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 [LAUGH]

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 So and then people came and said, well,

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 that ESP32 chip that has the Wi-Fi on board, it has many unused GPIOs.

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 Please, why don't you expose these?

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 We could use it for sensors and for whatnot.

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 And people were asking, hey, why do you only want to power wireless routers?

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 We need more power.

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 Give us more power.

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 Which was out of the scope of what I initially intended to do with this project.

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 But I said, okay, well, it opens up the possibility to use it for

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 other things as well, sensors, you will see a few examples later.

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 Why not?

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 So I extended the design, added one more pin header, and

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 increased the power, I doubled it basically.

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 But this wasn't the end, because people were saying, why only 100 watt peak?

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 We need more power.

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 Initially, I had thought, okay, there is commercial maximum

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 PowerPoint trackers on the market that you can buy from companies.

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 I don't mention those companies.

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 But of course, there's a virtue in having an open source and

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 open hardware project that you can extend and hack on.

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 The devices, since I used the ESP32, you can tell it into the machine.

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 Sorry, no SSH, but you can tell it into the machine.

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 You can FTP programs into the machine or download it from there.

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 You have, of course, a website, you have a web interface,

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 you have MQTT protocol as a telemetry.

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 You can configure it that it sends to two MQTT servers, its data.

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 So you can monitor it from everywhere and

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 you can run your own server to monitor it locally.

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 And of course, since the device now expanded to, yeah,

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 a device you can also use stationary, I also added the option to have a display

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 in the 3D printed housing, so you can also 3D print your housing.

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 But please use flame retardant PETG,

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 because it's strong electronics, high currents.

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 In the worst case, when you have like full power from the sun coming in and

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 full power demanded from the battery it can deliver up to 50%

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 50 amperes to your consumers.

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 So that's a current you can use for welding.

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 And the peak currents inside the device, they can go to 30 amperes at 400 watts peak.

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 So that's why you see this massive inductor coil which is used as the transformer.

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 Step number two of this device has been tried in an experiment in Ant Hill in India.

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 Because what can you do with 400 watts peak solar power?

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 You can run a small server and have a community that doesn't have internet access and give

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 them local services like local Wikipedia, local video streaming and whatnot.

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 So this is another nice addition.

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 The software running on the Frink Center is Nimble, it's another project.

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 I don't know if Eric who is involved in the project is around.

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 Two pictures of India, from India and also pictures that I use, I'm going to use in the

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 printed documentation how not to use the device.

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 The people in Ant Hill, they have built a bamboo tower with a metal housing where the

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 sun is blaring on that metal housing.

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 And they have put the batteries into the metal housing to make theft of the batteries more

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 difficult.

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 But at the same time they are frying the batteries.

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 And they're also frying my electronics.

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 The device is supposed to be mounted upright so you have some cool air streams to cool

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 that powerful inductor because at full power only the inductor can produce five watts of

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 heat and that heat has to go somewhere.

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 It's not supposed to be accumulated in that housing.

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 And then people came again and said, you know, why not build a device for watering plants

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 independently?

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 So I built a prototype based on the 100 watt version for irrigation.

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 So it measures humidity of the soil.

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 It controls water valves.

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 It controls a pump to provide water to the system.

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 And it also has a tank gauge to measure the amount of water that is remaining in the tank.

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 And of course it sends everything via MQTT protocol to the service you like so you can

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 monitor it.

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 I think this is quite helpful.

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 At the moment it's a prototype made with wiring on an existing device.

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 But I consider also making a PCB for this purpose.

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 Just yeah.

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 In last autumn I took these pictures that these are these drop irrigation outlets.

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 You can save a lot of water and you can treat your plants really well with this.

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 I learned I'm not too much into gardening that you should water your plants about one

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 hour before the sun goes up in the morning.

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 That's the best time where you avoid fungi growing on your plants and the water is used

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 most effectively.

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 And in times of drought, yeah, that might be a really good thing.

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 So I promised not to talk too much and spend too much time.

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 So I thank you for your interest.

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 And now we're ready for questions and answers.

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 [Applause]

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 So we have some questions.

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 So raise your hands so that we can see you and then we try to accommodate as many as

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 we can in five minutes.

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 Hi, are the design files or the schematics for the Mark II or Mark III available anywhere?

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 Mark II is available at electra.info and then you go to the site and you go to ffesp32.

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 I have not published Mark III because I'm not completely done with the development yet.

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 And if you want to produce them, please contact me for the latest files and also the support

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 with some of the components.

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 Because the chip crisis and the resource crisis also hit me.

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 I'm still waiting for some power inductors for like two months now.

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 Over there to the back.

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 If you raise your hands a little bit earlier, we can be prepared where we need to appear

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 after.

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 And you have to talk because it's a long way for the microphone to reach the next question.

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 And there we go.

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 Hi, first of all, thank you for all of this.

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 I have a good idea about what an MPP tracker is doing, but I have no clue how it is doing

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 it.

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 Could you maybe elaborate a bit on the implementation and how you specifically achieved this?

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 Do you know what a DC/DC buck converter does and how it works?

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 So basically you have in a standard DC/DC buck converter you have a feedback loop that controls

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 the output.

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 And there's just yet another feedback loop which is controlling the input.

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 So the pulse width modulation is controlled by the voltage at the input and finally when

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 you reach the charge end level at the output.

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 So because a standard buck converter you can try this without such an outer feedback control

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 loop it will just try to suck as much current as it gets and then you still have the same

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 effect like well it's even worse than just connecting your battery to the solar panel

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 without a DC/DC buck converter in between.

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 Other than that of course it's a solar controller as well so it protects your battery from overcharging

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 and deep discharging which would damage the batteries.

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 Oh, but I forgot to mention so far I have been using AGM led batteries but at the moment

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 I'm working on LiFePO, so lithium iron phosphate batteries and modify the charge controller

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 in the software.

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 I don't need to do anything in the hardware.

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 Any questions?

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 More questions?

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 I see this guy.

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 Oh there, yes.

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 What is the voltage for the batteries?

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 Can you configure it and in which range?

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 That's a very good question.

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 No, at the moment it's 12 volts so you can charge up to 14.7 volts and you can control

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 it from software.

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 So use the chemistry you like.

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 If I would make some changes for like 24 volt systems then the power capacity would double

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 also.

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 But I'm personally using systems like these and I prefer having like a single 12 volt

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 battery rather than have several in a row but I know many people are saying well why

242
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 not get 24 or 36 or 48 volts but at one point I'm going to do it probably and of course

243
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 the challenge for people asking hey why only 400 watts, it continues.

244
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 Okay anyone else?

245
00:19:10,670 --> 00:19:13,310
 Otherwise I would have a last question then but go.

246
00:19:13,310 --> 00:19:18,750
 Or tell if it's, sorry, I would repeat it otherwise.

247
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 One very short question about the autonomy of your project in Berlin.

248
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 You're told you can reach about 100% of autonomy.

249
00:19:26,350 --> 00:19:29,670
 Which calculator did you use for that assumption?

250
00:19:29,670 --> 00:19:32,310
 There's a manual.

251
00:19:32,310 --> 00:19:38,030
 When you go to the Electra site there is a big one, it's like 52 pages and I'm trying

252
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 to cover, well not everything but as much as I can and I like a printed documentation.

253
00:19:42,910 --> 00:19:45,510
 Of course it's a PDF, you can print it out, whatever.

254
00:19:45,510 --> 00:19:52,590
 Maybe I'll publish it as a book and people can buy it to support me.

255
00:19:52,590 --> 00:19:56,630
 Sorry, I'm lost.

256
00:19:56,630 --> 00:19:57,630
 Say it again.

257
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 The calculator.

258
00:19:58,630 --> 00:19:59,630
 The calculator.

259
00:19:59,630 --> 00:20:01,710
 The calculator.

260
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 I used, there is some global irrigation calculator and a very conservative estimate of the storage

261
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 for these dark times.

262
00:20:17,230 --> 00:20:23,910
 But it might, the weather changes if there is like three weeks of absolutely no sunshine

263
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 where the cars drive at noon with the lights on, then of course it could happen.

264
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 So I can guarantee 100%.

265
00:20:36,190 --> 00:20:37,470
 So I have also a question.

266
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 So commercial MPPTs are available of course but they are quite expensive too.

267
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 And if I want to use it with like low power solar batteries that I get often from second

268
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 hand market or something, it's not really feasible.

269
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 So how much is an invest to build open MPPT or like cheaply?

270
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 The biggest one or just you pick the size that you want.

271
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 When you build it on your own the question is how many are you going to build?

272
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 Are you just building one or a few?

273
00:21:12,950 --> 00:21:21,630
 I think if you order them in China, you can have them made in China, companies like Don

274
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 mentioned, then it's fairly cheap.

275
00:21:26,150 --> 00:21:28,190
 But of course you have to do some assembly.

276
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 They wouldn't do through hole assemblies and you have to do some initial programming and

277
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 so on.

278
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 Probably for the 100 watt version maybe 35 euros.

279
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 All in all.

280
00:21:44,830 --> 00:21:46,470
 Thank you very much.

281
00:21:46,470 --> 00:21:47,470
 Thank you very much.

282
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 And that's our time.

283
00:21:48,470 --> 00:21:48,470
 Thank you.

284
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 Thank you.

285
00:21:50,710 --> 00:21:52,710
 Thank you.

286
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 [Music]