Sunday, September 27, 2009

Power Usage Logging with the WELserver

Reading some forums about ground source heat pump installations, we noticed references to a logging system called the Web Energy Logger that collects data in your house and provides you with a detailed and customized view of how the systems in your house are operating. I bought a WELserver kit and have started installing some of the data collectors.

Here's the summary of what it does:

Simply put, the Web Energy Logger (or WEL) is the most economical way to monitor lots of temperature sensors, and a host of other energy related devices in your home or office. It's ideal to verify the performance or a solar thermal system, or to calculate the efficiency of a geothermal installation, or even to prove that your home really is Net Zero. Not only does the WEL give you a window into your energy environment, but it also provides a live snapshot and a range of trend charts that you can share on the WEB in real-time. Finally, the WEL records all your sensor data in monthly log files that are easy to download and import into programs like Excel. It's compact, versatile, and extremely configurable.

The minimal WEL in a Box is ideal for a DIY'er, and costs $375. In contrast, the more complete WEL Starter Kit is ready to run out-of-the-box with 10 temperature sensors and costs $525. All WEL's come with full monitoring software on the board, and a dedicated WEL logging site included in the price.

The monitors are all strung together in a daisy-chain configuration on a single twisted pair wire using the Dallas 1-Wire signaling technology. I got one of the optional current sensors and installed it in the electric hot water tank. Here is the sensor, one of the power wires needs to be threaded through the hole so it can detect current flow.

Here is the water tank. The orange wire had been installed without its protective shielding, so when that was fitted, we took the opportunity to add the sensor.

The recess in the top of the water tank has enough space to hold the sensor, with the black wire threaded through the hole.

The cover is in two parts, which gives easy access to the wiring again if needed.

At this point, I don't have the WEL configured. I need to add temperature sensors to the water pipes, and work out how to monitor the heat pump once we get it installed in place of the propane furnace. The WEL control box has an ethernet connection, and I'm not sure whether to run ethernet into the basement, or run the 1-wire cable around the house to monitor all the rooms. Spare wires in the existing telephone cabling can be used for this purpose.

Friday, September 25, 2009

GP Musumeci joins Netflix....

Adrian Cockcroft's Blog: Are any (ex-)PAE Snorclers looking for a new career?

My call was answered.... GP Musumeci started work last week at Netflix. He's the author of O'Reilly System Performance Tuning, and we worked together at Sun PAE in 2000-2002. Since then he worked on the operations side, building Time Warner AoL's video streaming service, and's infrastructure, then moved to become a developer of recommendation systems and distributed databases. The perfect mix...

Solar Power - Monitoring Consumption

We finally got Solarcity to install the consumption monitor, and we are now figuring out what the various bumps in the graph correlate to in terms of appliances. The first graph shows consumption on a hot day, with a portable room A/C unit left on all day. There is a characteristic bump in the morning that seems to correlate to re-heating hot water after showers, and random bumps during the day that are probably the hot tub cycling on to filter and maintain water temperature.

Another day where we didn't leave the A/C unit on shows much lower consumption. One of the common psychological effects of measuring something is a compulsion to optimize it, so we are now challenging ourselves to try and reduce consumption...

Since we are now on a time-of-use meter, the cost of electricity at nights and weekends is very low, and the cost in the afternoons during the week is high, but that is when we are generating more than we are using, so in $ terms, the meter is running backwards at high speed, and forwards slowly. This also makes it very hard to calculate the cost savings.

Total generation for the month is looking good. We turned on the system right at the start of the month, so the lifetime total includes a week or so before the output monitoring started to log data, and you can see the last few days of consumption data. We have had typical (for us) weather, sunny from the start of the day most days. We drive down into the clouds each morning. The drop off a few weeks ago was a cloudy spell that included about 0.25in of rain, enough to make sure the solar panels are nice and clean. There is a slow downward trend in the daily output, since the days are getting shorter and the Sun is lower in the sky every day. It's around the equinox at the moment. Over-all, I'm happy with how much energy we are getting, I expected to get longer effective days than most people, and it looks as if we will be generating about 600 KWh this month, our typical consumption has been around 1000 KWh.

Sunday, September 06, 2009

Solar Power - Monitoring Output

The SolarCity web based monitoring system didn't work at first, there was a problem with the data-logging board in the inverter but they were helpful and sent someone round to fix it. So now we can track how much power we are generating. The graph updates every 15 minutes, and it reports the amount of power every half hour, so when it shows 1.7 KWh that is equivalent to 3.4KW averaged over 30 minutes. So far the highest peak instantaneous output reported on the Inverter is about 4.2KW.

We are still waiting for the energy consumption metering to be added, which puts a second line on the same graph.

The day shown was a typical day up here on top of the mountain, it was cloudy elsewhere, but we had basically clear sky all day. and generated over 25KWh.