Monitoring solar installations
Monitoring system design notes
March 2012 update -- I've been thinking about approaches to monitoring solar PV installations for a long time now. I have more incentive now because I have contracted with Abundant Solar to install a system on my house.
The system will include an SMA "Sunnyboy" inverter. I have been reading up on them. As far as I can tell they come with Bluetooth now.
Currently I have a server based on a relatively efficient Mini-ITX board that I leave running all the time, so it is the obvious candidate to host the database.
I will need to figure out how to read the data, and this site looks like a very good place to start: http://www.on4akh.be/SMA-read.html A fellow ham and Linux enthusiast, no surprises there.
Gateway
My original plan was to install monitoring software on a hacked gateway router (such as a Linksys WRT54) and have it store the data on a server out in the cloud somewhere.
It could store data for at least 24 hours (1 week?) received from the sensors and then upload it. (No need for a continuous Internet connection.)
It could work like this:
Broadband = gateway is programmed to upload data hourly
Dialup only = gateway uses modem to upload data on next connect
No Internet = gateway uses modem to dial out daily
Communications
The inverters that I have looked at so far generally talk on
serial
- RS485
- RS232
or ethernet
Wireless
- WiFi
- Bluetooth
- Zigbee
some might use powerline communications
Whole house power usage
Brand power meter
WattNode "WattNode Plus for LONworks" = $500, software = $1000, Pulse output = $160
Energy Monitor EUM-2000 $200-275, display only, no computer interface.
"The Energy Detective" $140, display only, no computer interface. TED 5000
Inverters
Enphase
Enphase has a proprietary connection to ethernet, you connect the gateway to the Internet and it reports directly to Enphase. It's a subscription service.
"Auroras come standard with an integrated RS–485 port allowing monitoring of up to 31 inverters on a local PC using the free Aurora Communicator software. In addition, the indoor unit has an integrated RS-232 port for easy monitoring of a single inverter using a local Windows-compatible computer. Internet-based monitoring is also available and additional monitoring and communications options such as wireless, Ethernet and cell phone monitoring will be made available over time. Please contact Magnetek for the latest monitoring options."
Outback MATE and MATE2 system controllers have 9 pin RS232 connectors and use a proprietary protocol to talk to the systems.
Q. Do you have software for logging the performance data of the inverter?
A. The Command Center software that we currently have is sized properly for the PVP1100, PVP1800, and PVP2800-240. We have not updated the code for our newer models. We are currently developing a web based solution that will be compatible with the PV Powered and SunPower 2000, 2800XV, 3200, 4600, 5200, etc. The data monitoring will include a plug-in device for the RS232 port of the inverter that will store and send data via Ethernet cable (or wireless) to a web-based tracking system. We are in the Beta testing phase for the product and are planning on having a market release in June of 2006.
SMA Sunny Boy
I believe the current line has bluetooth; they used to have a "Radio Piggyback" board that talked to their fancy $600 "Sunny Beam" which is a tabletop display.
You can download free software from the SMA Web site that runs on a Windows PC.
The other option is to buy a $600 thing called a "Web Box" which is their proprietary communications gateway RS485 <-> Ethernet. The Web Box can monitor up to 50 inverters at a site, more than I need. :-) too.
Xantrex Xanbus looks like RS485 or CANbus with RJ45 connectors
