My First Project (Web Enabling my Off-Grid System)
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My First Project (Web Enabling my Off-Grid System)

by britesc on Sat May 12, 2012 12:16 pm


I thought I would outline my project so that if anyone thinks I am reinventing the wheel in places they can, please, advise me.
First the History:
Following an accident I am now disabled and partially sighted.
My wife and I had just bought a 16th Century Spanish Watermill needing total renovation, whilst I worked away in Switzerland.
Part of the project was to live off-grid utlisng Solar, Wind and eventually water to generate a normal 230Vac power supply.

After I blew up parts of my system by not knowing it was going wrong I have decided to create a web enabled sensor driven system, so even when I am in hospital I can check / receive warnings and be proactive not inactive.

I have decided to use an Arduino Mega as the Master / Web server and the controller for various odds and ends like flame and gas detection.
I will use an Arduino UNO as a slave to monitor each of the 2 banks of 12 x 2Vdc 1200Ah Lead Acid Batteries, for aggregated voltage and current, individual battery Voltage & Current, Temperature and State of Health (including Specific Gravity & Electrolyte Levels).
The system is 24Vdc feeding a Victron Inverter Charger.
I will use an Arduino UNO as a slave to monitor the 2 banks of 5 Solar panels & the 3.5K Watt Wind Turbine.
Lastly just because I want to I am using another Arduino UNO slave as a weather station.

All data is fed to the Arduino Mega for data logging and Web Serving.

I assumed measuring the SOH / SOC of the batteries via Specific Gravity would be easy as there would be thousands of Specific Gravity Sensors around.
Mistake number one: So I am attempting to make my own. I have now found that I can make probes out of Plumbers Solder as this is flux free and the only material the electrolyte will not degrade or contaminate the batteries.
So now I need 30 standard battery caps to fit the Hawker batteries so that I can attach the probes. As they are no longer used except on off-grid batteries this too is a challenge to find these.
Each cap will report, temperature and electrolyte level, plus I need to capture voltage and current.
Once a month the batteries are "boiled" by the Victron with system wide amps up to <100Adc so any sensor has to be hardy. Any suggestions on sensors greatfully received...

All will be housed in a purpose built box, which has 230Vdc fans and cooler plates embedded as temperatures in this part of Spain get high in the summer. Also the box will have a 2.8" Adafruit TFT Touch Screen controller on the front.

Currently I am extending the EEPROM library as each Arduino will carry details of who and what it is and does in EEPROM.
With such details as Master / Client ID, IP address, Gateway, MAC etc, where pertinent, which can be changed via web page.
I am also collating Arduino diagnostic routines to report the board type, RAM, SOH etc.

I am also trying to see if it is possible to store data on a standard 2.5" USB drive as backup, rather than just SD cards, it may be that I have to throw in my RaspberryPI as the data logger and or main controller.

I will post more on the project as I am going along, but please any advice gratefully received.

Kind reagrds,

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Joined: Thu Apr 26, 2012 2:02 pm
Location: Spain

Re: My First Project (Web Enabling my Off-Grid System)

by HooctAwnFonix on Sat May 12, 2012 4:40 pm

I would consider replacing the Arduino Mega web serving deal with a Beaglebone. You'll pay the same and get something with a lot more bells and whistles, not to mention a Linux OS. If you're not comfortable with Linux then maybe stay in Arduino-world but I think it's definitely worth investigating.
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Location: Cambridge, MA

Re: My First Project (Web Enabling my Off-Grid System)

by Alcornoque on Tue Feb 05, 2013 12:57 pm

I am also in Spain, in the South, and I am about to embark on a similar project.

I have 8 solar panels with a bank of 12x750 AH 2v batteries producing 24v all controlled by a Victron 3000w charger/inverter. Also a diesel 7kw generator with autostart that I hope to switch on/off using the victron virtual switch and/or arduino switching. I am surrounded by trees so a wind generator probably not much use.

I was checking the net to see if anyone had attempted an Arduino/Victron interface and I found your post. I wondered how you are getting on?

I have spoken to Victron and their inverters and chargers have an interface that is designed to connect to a PC using a USB port. The software that they supply tells you a lot of interesting stuff about battery condition, current draw etc. I wondered whether you used this dataflow as part of your system?

Anyway, I am keen to know how you managed as any input into my attempts would be very helpful.

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Joined: Tue Feb 05, 2013 12:44 pm

Re: My First Project (Web Enabling my Off-Grid System)

by static on Sat Feb 09, 2013 8:54 am

Eventually I want to do this as well. I'm in the process of building a datalogging network using Raspberry Pi's. I'd probably try to make the system an extension of my datalogging network. I used to use Arduinos a fair amount. I've found that the Raspberry Pi is pretty easy to use and presents some incredible capability for the cost. In built networking, USB and GPIO pins have really made it easy to get started. I had to relearn Linux after being away for over a decade, and knock the rust off my Python skills, but I'm coming along nicely.

I'm REALLY interested in a charger/inverter that could be monitored and/or controlled through an Arduino. I'd definitely try to adapt that for my use, and I'd love to hear your progress.

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Please be positive and constructive with your questions and comments.