Canyon Edge Aurora/Solar now publishing to PVOutput.org

A big thanks to Eric Sandeen for introducing me to PVOutput.org -- a website dedicated to collecting and graphing PV/Solar data.  It has a really well documented service API.
I updated my cronjob that logs data from my Solar Inverter using Curt Blank's aurora (which I've packaged for Ubuntu), to additionally submit my data to PVOutput.org.  You can see my array's current day live data at: http://pvoutput.org/intraday.jsp?sid=3085, and from there, click through various views of daily, weekly, monthly, etc. reports.

I backfilled the last 1.5 years with monthly output totals, but as of July 31, 2011, I should have much more granular outputs, corresponding my my cronjob which runs every 15 minutes.

Having done that, I see that our array is currently ranked 3rd in overall power generation of all arrays registered at PVOutput.org!  That won't last too long, though, as there are a couple of much bigger arrays gathering sun a lot faster than ours, so I grab a screenshot for now :-)

A current snapshot from my inverter shows these values:

Current date/time: 01-Aug-2011 12:30:01

Daily Energy               =      11.692 KWh
Weekly Energy              =      47.445 KWh
Monthly Energy             =      11.691 KWh
Yearly Energy              =    6253.736 KWh
Total Energy               =   18596.278 KWh
Partial Energy             =   10700.143 KWh

Current date/time: 01-Aug-2011 12:30:05

Input 1 Voltage            =  279.369812 V
Input 1 Current            =   12.553665 A
Input 1 Power              = 3507.114990 W

Input 2 Voltage            =  272.658813 V
Input 2 Current            =    3.934551 A
Input 2 Power              = 1072.789917 W

Grid Voltage Reading       =  235.901169 V
Grid Current Reading       =   18.746544 A
Grid Power Reading         = 4391.979980 W
Frequency Reading          =   60.016804 Hz.

DC/AC Coversion Efficiency =        95.9 %
Inverter Temperature       =   67.880447 C
Booster Temperature        =   61.183586 C

The key number there is: Total Energy =   18596.278 KWh.  That means that we've generated 18.6 megawatt-hours of power to date!

I also added the PVOutput widget to the bottom of the right column of this blog.

:-Dustin

My First Year of Solar Power

I've posted a few times now about the 6.7KW photo-voltaic (solar) power system we have on our roof in Austin, Texas. It was activated one year ago, today.

Many, many people ask me about it. It has been operational for about a year, so I can finally analyze it's performance each month out of the year. This is important because the energy produce depends greatly on the position of the sun in the sky, the length of the days, and the weather. Different amounts of power are produced at different times.

I'm currently using Curt Blank's aurora program to gather data from my inverter. I have packaged this for Ubuntu, by the way. You can find it in Ubuntu 10.04 and beyond.

My current inverter reading as of today looks like this:

Current date/time: 15-Sep-2010 11:30:02

Daily Energy               =       7.314 KWh
Weekly Energy              =      91.434 KWh
Monthly Energy             =     366.448 KWh
Yearly Energy              =    7123.188 KWh
Total Energy               =    9433.281 KWh
Partial Energy             =    1537.161 KWh

Current date/time: 15-Sep-2010 11:30:05

Input 1 Voltage            =  244.048767 V
Input 1 Current            =    9.157255 A
Input 1 Power              = 2234.816895 W

Input 2 Voltage            =  255.783203 V
Input 2 Current            =    3.767791 A
Input 2 Power              =  963.737732 W

Grid Voltage Reading       =  239.640839 V
Grid Current Reading       =   12.036012 A
Grid Power Reading         = 3196.468750 W
Frequency Reading          =   59.966419 Hz.

DC/AC Coversion Efficiency =        99.9 %
Inverter Temperature       =   54.750835 C
Booster Temperature        =   49.749878 C

The most important number above (for this post) is:

Total Energy = 9433.281 KWh

In the last 365 days, this system has produced 9.4 Megawatt-hours of power.

What does this mean in terms of cost savings? Roughly, I know that electricity in Austin is about $0.115/KWh, so that's approximately $1,085 in savings on my electric bill. The real formula is actually a far more complicated differential equation, as I buy and sell electricity at two different rates, the rates change slightly every month, etc. But this is a reasonable ballpark figure.

Austin Energy actually has a web application where I can view and analyze my usage online. Here's a screenshot of my last 2 year's usage. Note the "Solar kWh" row, as well as the year-to-year difference in "$ Billed".

I can also download these stats in a CSV format, drop it into a spreadsheet and print some pretty cool charts. Analyzing the data directly, I can see that my solar investment has saved me exactly $1,210.71 over the last 12 months -- about $100/month, which is what I expected when I purchased the system.

Accounting for both the Austin Energy PV Rebate, and the Federal Tax Credit, our system is well on its way to paying itself off in just a few short years.

Once again, thanks to the outstanding individuals at Texas Solar Power Company in Austin for their outstanding service and timely installation.

As George Harrison wrote, "Here comes the sun!"

Doo do doo doo,

:-Dustin

Solar Installation - Part 5

As of 11am today, my PV system generated its first Megawatt-Hour of electricity

Current date/time: 30-Oct-2009 16:00:09

Daily Energy               =      27.766 KWh
Weekly Energy              =     123.155 KWh
Monthly Energy             =     634.408 KWh
Yearly Energy              =    1025.502 KWh
Total Energy               =    1025.683 KWh
Partial Energy             =     935.313 KWh


Fri Oct 30 16:01:29 CDT 2009

Current date/time: 30-Oct-2009 16:01:25

Input 1 Voltage            =  300.503571 V
Input 1 Current            =    9.931437 A
Input 1 Power              = 2984.432373 W

Input 2 Voltage            =  293.223511 V
Input 2 Current            =    4.005443 A
Input 2 Power              = 1174.490112 W

Grid Voltage Reading       =  244.775589 V
Grid Current Reading       =   16.397514 A
Grid Power Reading         = 3985.880371 W
Frequency Reading          =   60.003841 Hz.

DC/AC Coversion Efficiency =        95.8 %
Inverter Temperature       =   49.636932 C
Booster Temperature        =   42.354176 C

I owe a big thanks to Curt Blank, who wrote aurora, a GPL program that communicates with my Aurora Solar Inverter and generates the statistics shown above. We have been talking over email through the last few weeks, trying to debug a few issues with my inverter, which is a newer model than the one he developed his software against. I have a cronjob that polls my inverter every 15 minutes, logging statistics about my solar power generation. And I will be packaging aurora for Ubuntu Lucid shortly. Thanks for all your help, Curt!

The system has been running now for almost 50 days. I have averaged about 20.6 KW-hours of generated energy per day over the last month-and-a-half, with a maximum of 36.2 KW-hours in a given day. Now the days are getting shorter in the Northern Hemisphere, and we're in the rainy season here in Austin. So I'm looking forward to the long, sunny days next summer.

My PV system saved about $80 on my October 2009 electricity bill, which is really close to my predicted target.

Stay tuned for one more installment in this series, regarding the actual solar rebate!

For other articles in this series, see:
http://blog.dustinkirkland.com/search/label/Solar

:-Dustin

Solar Installation - Part 4

As of September 1, 2009, all 38 panels are now on the roof, and hooked up to the inverter, thought it's not yet turned on.

I had my inspection with Craig of Texas Solar Power Company, and David of Austin Energy today.

We spent about an hour going over the entire system. They turned it on for a few minutes, verifying the functionality. David went over every aspect of the design and installation. He noted a couple of things he wants to see updated in the CAD drawings and documentation. Craig is supposed to send those over to David as soon as possible, at which point my installation should be approved.

Now, I'm waiting 2 weeks for Austin Energy to come back out to my house to replace my current electric meter with one that can handle the PV junction. At that point, Austin Energy will actually turn on my system, and I will be generating Solar Power!

And then my rebate will be submitted for processing. I hope to see that rebate check in 6-8 weeks.

Many people have asked for more details about how the system works, and how my electric bill will be calculated.

The PV system will only generate electricity when the sun is out. Many factors will affect how much electricity is generated, including cloud cover, cleanliness of the panels, ambient temperature, length of the day, and the time of the year.

My system consists of 38 panels that are rated at 175 Watts apiece, for a theoretical maximum of 6650 Watts of output. The 38 panels are divided into two separate arrays. The Southwest-facing array consists of 3 strings of 9-panels apiece. These strings generate 357 Volts, 356 Volts, and 355 Volts apiece. Note the subtle difference in voltages. This ensures the direction of the flow (electricity always flows from higher voltage to lower voltage).

The amperage varies with the quality of the sunshine, and affects the output wattage. More sun yields more Amps, and thus more Watts. The other, Southeast-facing array consists of a single 11-panel string, which generates 439 Volts.

It is the job of the inverter to combine these two arrays and produce an AC current. My particular inverter is rated at 96.5% efficiency, so during the best hours of the day, I should see somewhere around 6400 Watts of electricity. During yesterday's test around Noon, with partial cloud cover, the system was generating 5550 Watts -- and this was far more electricity than I was consuming at that time.

The inverter is tuned to produce an AC voltage that is slightly higher than the power coming from Austin Energy's utility pole. This ensures that I use my solar generated power first, and any remaining flows back into the city's grid.

Now 6400 Watts is far more energy than I will be consuming during the daytime. However, at night, I won't be collecting any sunlight. During the day, the surplus will be used by others on the energy grid, and Austin Energy only buy that electricity from me at 40% of the price that I pay them for the electricity I use at night ;-) Such are the breaks... They pay the rebate, and thus they get to make the rules.

So we'll need to adapt our electrical usage model in order to maximize our savings. It will be in our best interest to run our laundry, dishwasher, and hot water heater during the daytime.

On a separate note, I'm quite eager to play with the serial data output on the Aurora inverter. Of course, my inverter came with a CDROM of Windows software that is worthless to me. Thankfully, someone out there has written a GPL application that communicates with the inverter's interface. I can't wait to play with it, once my system is turned on. Assuming it work's, I'll get it packaged and included in Ubuntu Karmic+1!

For other articles in this series, see:
http://blog.dustinkirkland.com/search/label/Solar

:-Dustin

Solar Installation - Part 3

Alright, so with the rails up, we're ready for Part 3...installing the panels. The panels are mounted on the aluminum frames, and connected to a DC voltage collector, which feeds into the AC-DC power inverter.

We have a total of 38 modules going on the roof, in 3 separate "strings" or "arrays" (solar guy's terms). To those of us that are programmers:


power_t *solar1, *solar2, *solar3;
// versus
power_t solar1[16];
power_t solar2[11];
power_t solar3[11];


Heh, okay, bad joke!

A little over half are installed now. We're waiting on the shipment of the rest. Hopefully, the rest should be installed by the end of the week. Stay tuned...

For other articles in this series, see:
http://blog.dustinkirkland.com/search/label/Solar

:-Dustin

Solar Installation - Part 2

Step 2 is installing aluminum brackets on the roof, to which the solar panels will actually mount.

I was chatting with one of the two installers. He noticed that I was wearing a Linux Foundation t-shirt, and he mentioned that he ran Linux on his older computer. Ubuntu, as it turned out. He said that he found it mostly user-friendly, and was able to do almost everything he could under Windows, except use Real Player to listen to his favorite college radio station, kdvs.org.

So I checked out kdvs.org, and found multiple m3u streams, for both mp3 and ogg formats. Within minutes, we were streaming to the outdoor speakers while they were working on the roof ;-) When he got home, he confirmed that he was able to do the same with Amarok.

For other articles in this series, see:
http://blog.dustinkirkland.com/search/label/Solar

:-Dustin

Solar Installation - Part 1

So Step 1 in our solar project was upgrading the electrical panel. All of my breakers were spoken for, so I had to add a line side distribution box for the solar to interconnect. The junction box at the bottom allows me to add a sub-panel into my main distribution panel. The PV system will connect into this dedicated sub-panel.

Thanks to Joseph of Jackpot Electric for the nice, clean installation!

For other articles in this series, see:
http://blog.dustinkirkland.com/search/label/Solar

:-Dustin

Going Solar in Austin, Texas

We're working hard to make your Ubuntu Server as energy efficient as possible, and I'm quite proud of that.

Personally taking it one step further, last week I signed a contract on a 6650W Photovoltaic System, to be installed on my roof while I'm in Dublin for the Karmic Distro Sprint.

The system consists of a total of 38 Solarworld 175 Watt Solar Panels, and a PVI-6000-OUTD-US Aurora Photovoltaic Inverter. It should supply the majority of our electricity (according to PV Watts) and pay itself off within a couple years (after rebate).

We contracted the system through my buddy Vincent Guerrero of Texas Solar Power Company, here in Austin, Texas, taking advantage of one of the most generous and progressive solar rebate programs in the country, offered by Austin Energy.

I figured I should blog our experience in case anyone else out there is considering the same. I'll keep you posted on the installation and performance of the system.

For other articles in this series, see:
http://blog.dustinkirkland.com/search/label/Solar

Cheers,
:-Dustin