WiMAX Solarcam Pi

[TarjeiB]

I'm currently running a solar powered setup at my cabin for taking a webcam image every day and uploading to http://bjortjonn.no.

It's completely solar power driven and somewhat inefficient, only allowing me an uptime of 1 hour per day. It's using a 12VDC->220VAC->55VDC converter for the WiMAX antenna, and a 12V Netgear WNDR3500 router with custom Linux firmware running the webcam and atmosphere sensors.
The panel is an old 60w, and the battery 215Ah.

I'm planning on replacing this with, or rather adding, a RPi to make me able to get an uptime of "daylight" for the webcam using "motion" or similar to record, and 1/2 hour or on-demand WiMAX connection to upload the results. Panel will be upgraded to 160w and battery to 450Ah.

SolarcamPi.png (11.95 KiB) Viewed 14708 times

What I've figured I need so far (already ordered):

• Timer/Daylight sensor to switch on and off power to the RPi
• MOSFET relay to switch on and off router/wimax
• RTC to know when to switch on and upload for daily snapshot
• Powered USB hub for cam and sensors
• 12V-5V buck converter
• 12V-48V boost converter

In addition I've added a manual switch to turn on/off router and wimax for when I'm at the cabin and would like internet on.

The webcam and atmospheric sensors are already covered and should be working fine, I'm using a Logitech QuickCam Pro 9000 and a USBTenki sensor.

What I need help with:

• Verifying it's a sound setup
• How to make the RPi powerloss-ready before the daylight sensor switches off
• Making a daylight sensor
• Optimizing power efficiency (RG1/RG2, converters)

Hopefully you'll have some helpful hints for me, I'll post images as it proceeds off the drawing board
Making things cheap is not necessary (panel and battery are like £2000 alone), making them power efficient is.
In the end I'm hoping it can all stay up 24/7!

[TarjeiB]

Here's the current state of this project:


There's 3 power interfaces in this; bottom right is 12v in. Bottom middle (leftish) is 12v out (for wifi router), and bottom left is 48v out (for WiMAX antenna).

The 12v power comes in at the bottom right; feeds into a light sensor switch with some logic. The light sensor switch will turn on power in the morning at the top, and put a 3.3v signal. In the evening, it will turn off the 3.3v signal and then cut power 5 minutes later.

Top right is a 12v-5v converter. On the left is a 12v-48v converter.

There is a RTC (blue chip in the middle), a MOSFET to control the power to the two left outputs, and a manual switch to override the MOSFET.

Tried and working:

• MOSFET to turn on and off power
• RTC
• light sensor power
• Manual switch

Todo:

• Shutdown on light sensor 3.3v low
• USB camera
• USB Temperature sensor
• router/wimax power on/off scripts
• Upload script for images/videos

I'm having major problems with getting an usable output from the USB camera, which is strange - as it is working with no CPU usage directly on an OpenWRT router currently.

[TarjeiB]

Small update, mostly for myself. Shutdown scripts working, webcam motion scripts working, upload scripts working, and it's been up and running for two months now.

However while remote installing some python module it pulled python 6.something and locked up completely. Since it is a very remote installation and it's now Autumn, I have no way of fixing it (no good way of getting there between summer and winter until there is enough snow).

I'm hoping it's just a software problem and nothing has broken, froze, sort circuited or ran out of juice.

[bgirardot]

Interesting project. I will eventually be doing something similar so I subscribed.

Bummer about the lock up taking it out after 2 months of working fine.

[arcanon]

Hi, very interesting project. How did you run time per day turn out? did you acheive full daylight hours?

[TarjeiB]

Hi, very interesting project. How did you run time per day turn out? did you acheive full daylight hours?

I managed ~9 hours (daylight time) on the Pi, and between 1/2 an hour and 2 hours on the WiMAX antenna.
It seems to have ran fine, however I don't yet know if the drain has been too big or small, since I've not been there again to check

I really need to make some voltage sensor that will report battery status remotely...

[bgirardot]

That WiMax device sounds like a real power hog. Do you have a link to a description of the device somewhere on the web or the specs for its power requirements?

[TarjeiB]

That WiMax device sounds like a real power hog. Do you have a link to a description of the device somewhere on the web or the specs for its power requirements?

It's an Alvarion BreezeMAX PRO 1000 - and hard to find specific stats on it seems!
I'll have to have a look on the antenna itself when I get there, but I'm betting it'll be too weather worn to make out. Or maybe just take the effort of mounting a multimeter in the circuit and see how much it actually draws....

http://www.alvarion.com/phocadownload/D ... 010_lr.pdf is the datasheet (of a newer revision) but it doesn't say anything about power....

[bgirardot]

Oh ya, I see, that is a high end commercial unit. Looks too nice to do any tinkering with.

[yop]

Hi, it is really strange that you cant have more power.

My house is off grid and I have a system with only one 80w 12v solar panel on a 130ah batterie. It is powering 10 3w led lights, a water pump 6amp who run for washing dish and 2adult showering, a electrificator for horse and an android phone as permanant 3g wifi router. I live in france, in the middle not so cloudy but not so sonny either.
The controleur never stoped due to undervoltage, now at the worst period. Its still at 12+ v the morning.

The is a problem with your system.

On the other side i have a epsolar 24v 30a , a 275ah 24v battery and 800w of pv. This is only for 220v.
I need to talk with you about this, as i need to find a way to use the com port to monitor with a rasp.

Maybe you should convert directly 12 to 55v. Look for car plug laptop charger. Or at least find a way to cut the invertor at night to keep it autoconsomption in the batterie.
Is wimax the best idea? Why not 3g dongle or similar? So much lower consomption!
Im sure you dont transfer that much data. And the rasp could compress rapport before sending it?

For temp mesurment why not using a resistor on gpio (cant remember the name but there is some resistor who change with temp.)

You should really sell back you wimax and get a data plan. I dont know the price of the antenna but it should pay few years of a really small 3g data plan.

Here you will ruin you by buying batterie every x years, adding more solar panel and spending all the power in wimax. If you cant do it more than an hour with 1 you'll not do much better with 2

Or get a TriStar as regulator, there is com port fully fonctionnal, given with all the software part needed.


But in my case, i really need to communicate with the epsolar, as i cant afford even a small pwm tristar...

[yop]

And panel and batterie are not that expensive.

1 can get 3kwc of pv for 2000€. So somebody stole you somewhere.

Keep you battery like that. Eventually buy another panel. But no more.
With the snow it should charge at full speed, this is not normal that you have so small power.

Put your panel in winter mode, nearly vertical 70° or so. Full south.
Keep in mind that if one cell is hidded by dirt, snow whatever and its the whole pannel who stop producing.
In pv the voltage is the on of the weekest cell.
Go on ebay buy 3 100w pannel for 260€ , if you want, its not so expansive.

If you save a lot a money with my advice i'd like a nice TriStar controleur for birthday, pwm the cheapest one
Or better : some way to make rasp and epsolar talk each other!

[bgirardot]

Or better : some way to make rasp and epsolar talk each other!

Let us know if you figure out the EPSolar com port (it is physically an RJ45 for anyone interested), I have one too and wouldn't mind making use of it. Although to be honest, if it reflects the LCD display, I think I would not trust the numbers, my own measurements of the battery are often different than the EPSolar unit's measurements by almost 1/2 a Volt.

[yop]

I would not trust the number either. I wrote to epsolar but no answer yet.

If there any way to mesure with a rasp before the mppt (so mesure 60v *A) i dont need to talk to the regulator.

Because i want to dynamicaly plug/unplug more pv in order to always charge at full rate.

But as mppt can charge lower that what come in, i must know power input in watt and outpout in amp. So i can calcul if i must ad 1, 2 ''' 8 string. To compensate grey weather.

So i keep a small battery parc and cheap regulator. There is to much dirty battery and poor people, so i try to make a cleaner système, very evolutive.very cheap and reliable.

And i even cant afford a 150$ tristar 45pwm in order to'do it easily

[yop]

It would not be tje same as the LCD. It is said that the lcd refresh every 10sec. So its just a toy.

There must be some way to do it. But it look like a really bad hack



For voltage mesurement, have a look to tinkerforge website

[bgirardot]

It would not be tje same as the LCD. It is said that the lcd refresh every 10sec. So its just a toy.

There must be some way to do it. But it look like a really bad hack :-)



For voltage mesurement, have a look to tinkerforge website :-)

The tinkerforge stuff looks cool.

At the moment I just do my own voltage and amp measurements with an ADC Pi board wired to the PV/Battery/Load wires going into the EPSolar charge controller.

Now if we could get France to stop sending us all these clouds, I could get my batteries charged :)

[yop]

No they came from belgium and germany but i appreciate you take some, i cant handle all by myself, i also need a computer working

On the epsolar, i got 3x3 80w pv

So its about 60voc 5amp each 3 string.
So 60voc 15amps input


Can your adc pi board handle this?

Otherwise i think i will use the rasp with

2 current/voltage bricklet from tinkerforge
2 30v 16a x8 relay board from Conrad
2temp sensor
And a dump load home made connected to the nf plug of each relay and the no side connected to the battery

I'll rewire my PV to 24v instead of 36 and ill resell my epsolar.

All this hardware will cost 180€ and control the batterie charge in shunt/pwm mode. Ill be able to control a solar field up to 5400watts and a btterie charge rate from 10 to 240amp

With time and work we ca make the first open source mppt emulated solar contrôler with all the geek option (log, webcam, distant accès, small domotic, even android phone controled and speaking ' hi yop your batteries are full you can now play game or use your driller or whaterver you want but do it and dont bother me again' humor is important to humanise the house:-)

My batterie is good for my need, gaya not enought .

And most important, it evolutive, so youndont need the same spec pannel on each controleur. You dont care, just 24v and 15amp max on each relai . And you can start with 100w and buy with your income permet it.
Does it sound cool to you?

[bgirardot]

With time and work we ca make the first open source mppt emulated solar contrôler with all the geek option (log, webcam, distant accès, small domotic, even android phone controled and speaking ' hi yop your batteries are full you can now play game or use your driller or whaterver you want but do it and dont bother me again' humor is important to humanise the house:-)

Does it sound cool to you?

It is like you are reading my mind, that is exactly what I would like to do. But I am much less informed than you are about how to do it.

the ADC Pi board only takes 5v so I use resistors to divide the voltage down to under 5v. I only have 1 small panel, 30w and a 20Ah battery to drive my Pi and inexpensive web cam for now.

The amperage sensors are "hall effect sensors" so not in line with the current but work up to 100A (I use one tuned for 20A) and they put out 2.5v at 0 amps, going down to 0v or up to 5v depending on which direction the current is flowing.

[yop]

Well, im really aware about solar things but not about electronics.


Like for the relay card i juste learned to use mosfet piloted or to add diode 'de roue libre' (sorry i dont know in english) to avoid inductances when tension change.

The point of opennsources communitys is to share knowledge. So im sure all together we can easily think (electronicians) code (dev) and improve (all the other geek) this project.

Most of the code already exist, also the hardware, even better all is open source.

What i have in mind does not exist, so its cheap and everybody will be able to access renuable energy accross the world.
Without much batterie. That you must change and recycle every few years. 30years for nowaday solar pv.
Calcul is simple.

Also i live beetween 2 nuclear power plant. 60km from each. In sunny day i can see their clouds. I dont know what you think about it but... i dont like this at all.

For me its just a hacking game, but it could be a nice gift to the world. So many of ly friend would like but cant afford high priced system.

[TarjeiB]

Hi, it is really strange that you cant have more power.

The is a problem with your system.

You're quite right, there was. It leaked current which turned on the WiMAX antenna during the whole night every night. Now fixed!

Maybe you should convert directly 12 to 55v. Look for car plug laptop charger. Or at least find a way to cut the invertor at night to keep it autoconsomption in the batterie.
Is wimax the best idea? Why not 3g dongle or similar? So much lower consomption!
Im sure you dont transfer that much data. And the rasp could compress rapport before sending it?

For temp mesurment why not using a resistor on gpio (cant remember the name but there is some resistor who change with temp.)

You should really sell back you wimax and get a data plan. I dont know the price of the antenna but it should pay few years of a really small 3g data plan.

I am converting 12 to 55, that saved me alot of power, it's in the diagram and picture. But it was wired so some leakage current turned it on at night...

I have to use WiMAX since I need proper broadband when I am there, and cellular reception is very bad (EDGE at best).
Also I already have a temperature and humidity sensor, I just need to get around to configuring it again after breaking the first one

There's two problems with my setup though which you're quite right, breaks alot of the efficiency.

First is the 60w 20year old solar panel which is turned towards west. Second is the northern location which makes a BIG difference from France during these winter months. But moving the panel (or buying a new one as it is) will fix this.

Also, living in Norway is the reason for the silly panel/battery prices... Unfortunately.

Thanks for all your input, much appreciated

[TarjeiB]

And here's a picture of the completed setup!

1. Power comes in through here which is a battery guard, and cuts power if it falls under 12V.
2. This is the circuit to turn on and off the power when it's light/dark. Also warns the Pi about an imminent poweroff by setting a GPIO to zero 5 minutes before power is cut.
3. The actual light-sensitive resistor, drilled through the front of the cupboard.
4. Override switches for light sensor and MOSFET for WiMAX, so I can turn on and off the system when I'm actually there.
5. 12-5v converter connected directly to the GPIO pins.
6. My Pi! A Wi-Fi stick and hostapd enabled so I have an access point as well for when I am there.
7. RTC so the Pi knows what time it is and when to turn on and off stuff.
8. MOSFET to turn on and off the WiMAX antenna power supply.
9. The WiMAX power supply (12v-55v converter).

I'm really pleased with this setup now, although there's definately more changes planned.

[yop]

Why is it so expensive in norway? 20years ago solar panel was out of price but now..


You can watch on ebay, write in maybe. ( panneaux solaires )
There is a guy in belgium who sell chinese panel for cheap (3x125w for around 300€)

Also this is definitly a good idea to put them full south as you wilm loose 20% efficiency for each 10° east or west. As you are far in north i presume on winter sun is very low in the sky so put your panel nearly vertical.

Go at midday and the panel should be as more perpendicular to sun light as possible. In all direction. Think if there was a little hole in the panel, sun should go thru it.
You will gain a lot.

That sad that you need wimax, maybe a 3g dongle with external antenna on the roof. Of is it the full area who not properly covered?

I thought norway was more advanced than france in renewable energy (2.3% green in france that sad and people dont care here they prefer a bigger tv or car... )


Nice setup anyway, can you share the code for mesurement and relay control ?

Also for the epsolar , a friend told me it should be modbus tcp but i dont think we can olug in directly in ethernet port as it send current to the lcd screen. But if someone is aware zbout modbus, that could worth a try.

I think im gonna go to a pwm tristar, realy cheap and good brand. And also on mppt controleur all the panel MUST be the same with same spec otherwise ppt doesnt calculte properly and a lot of current is lost. So pwm is less optimised but more evolutive.
Znd tristar talk with pc really well. It can also control relay by itself so even the rasp can be stoped at night. More efficient in your case i presume.
Also a light sensor instead of rtc, in case of really cloudy dark day it dont start until zfternoon ans save battery.

If you cant import panel because of taxes we can try something, i send you from france with a bithday card or similar, they will not tax you a free présent, and the sending adresse would be mine so not linked to resseller.

[yop]

I finaly got an answer from the german resseller of epsolar so we will communicate easily with the epsolar now.

As i cant attach neither .doc .pdf or send a zip here i'll try to post it somewhere later this day.

It seem simple to do. Maybe directly trough ethernet after cutting the alim wire of the rj45 cable.

[yop]

Hope this would work

http://db.tt/knGFNSfO


Hope we will do a nice interfacing to play with

[thinman]

hello!
I'm looking forward to build a project like yours myself except the only doubt i have is how did u manage to setup a WiMax communication ? did u use a Wi-Max compliant router or some kind of module?? where can i find one? could u provide me with more details about your WiMax setup

[TarjeiB]

Sorry for late reply - the WiMAX setup is delivered by a provider here, so it's nothing I have set up myself. I got the subscription and antenna from them, and they were kind enough to provide a DC injector instead of the usual AC mains injector for power supply. So for me it works like any broadband modem.