Inverter and Data Logging
[ Updated 10/2011 - This page is now historical in that the
Inverter has changed. Much of the information still applies but the inverter
failed and was replaced under warrantee with a different brand. See information
in the 2011 annual report about that.]
The inverter used is a Sunpower SPR-4000x (Spec-1, Spec-2). Note that this is the same as the Xantrex GT Grid Tied inverter. Xantrex provides a very nice monitoring station that provides the same functionality you can get from standing outside at the inverter. The also provide a monitoring tool for Windows operating system available at the same link above for Xantrex GT Grid Tied. Look in the upper right corner and click on "GT-View Inverter Software" to download it. Sunpower also provides a network tool for monitoring your data but this requires that you store your data on their servers.
All of these did not really do what I wanted for piping the data into my Linux server and logging the data locally. However, Stephen Kang at Namaste had some info to help with this. First of all he pointed out that on that same Xantrex page in the upper right there is a link to the Data Sheet. This includes another link to download all the RS232 connection commands. (It also has a link there as well to get the GT-View software.) With the RS232 commands one can write a program that will talk to the inverter. I was getting ready to do that when I got a reply from Xantrex with some info on where to look for that type of program, http://www.solar-guppy.com/forum/ and http://www.xantrex.com/forum/default.asp Crashing around there a bit lead to a couple of folks that had already done this. Both programs are really sets of scripts or tools and are available under public copy protection, please read the various copyright info for each. NOTE: Both these guys are pretty busy with their real jobs, so please don't pester them with lots of questions, be prepared to pretty much do your own thing using their software as a starting basis, not expecting it to be a polished, completed, ready-for-market product.
The first was written by Tony Luck. His web site is at http://solar.sippelhouse.com/ and the software itself is available for download by following the Details: link on that page. This is written in C and/or C++ and stores the data to files. He has some scripts for creating graphs and such as well. It is then kind of up to you to create your web page and get the info up on it, fair enough. This package of scripts is a pretty nice program, but not for the faint of heart. You really want to be conversant in C programming, Linux OS, and the various tools there too use this. I worked with it a bit but later decided to go with the second program that I found of interest, mainly because it used a database structure.
The second batch of tools/programs is written by Justin Shumaker and uses perl scripts to access the Xantrex Inverter. The scripts then save off the data into a MySQL database. So if you are interested in using this set of tools be ready to learn, or already know about, perl, MySQL, gnuplot, and html or other web programming. This is the tool set that I finally used. His web page is at http://solar.js.cx, and there is a link on that page for downloading the software. Further, it is recommended that you be using a fairly up to date version of the OS and related packages. I found, for example that Red Hat Enterprise Linux version 3 was using versions of some perl parts that were too old to do what was needed. Use RHEL4 or RHEL5 or the equivalent Fedora. I am not conversant in Ubuntu or Debian or other flavours, so you will need to investigate that yourself.
Once I got going with this, I did quite a bit of modification to Justin's scripts, and I am currently still modifying them a bit. My versions of Justin's work can be seen by clicking on the Power Graph and Cost Graph buttons on the left. I am open to suggestions as to other graphs or data, or additions to the existing graphs. I may not implement suggestions but I'm open to hearing them for consideration. If you would like to download a .tar.gz copy of my version of the files you can click here. [NOTE: Justin's version should be obtained directly from his site.]
A quick note here about warrantee stuff and Sunpower and Namaste. About the time I got my first pass logging going, I noticed that there were some spurious "zero input" values. I'm tracking daily with ten minute intervals and some of these were reporting a zero input from the panels, bounded by normal large values. At the same time I notified Namaste about this they were also contacting me to let me know they wanted to test my inverter for some problems. Xantrex/Sunpower had some inverters that seemed to have a problem and they wanted to come by and check mine. Namaste coordinated this and an engineer from Sunpower/Xantrex came by and found some issues with the firmware version that was installed. They just burnt in some new firmware and it has been fine since. In addition they gave me a $50 gift certificate to Amazon.com to compensate for the bother. That is about as good as it gets for follow up on warrantee.
