Monthly Archives: April 2018

A fortnight with solar panels

Well, it’s actually only been 13 days, not two weeks, but close enough, since the installation started a couple days earlier. Our system was installed by Southern Energy Management, based in Morrisville, NC, who did an outstanding job. The system installed is composed of 15 REC TwinPeak 290 panels, 11 facing due south and 4 facing west, for a nominal capacity of 4.35 kW. The plan had been for all to face south, but the roof layout and potential for shading dictated the placement. With some of the panels facing west, the peak capacity is slightly less, but the “tail” of power generation is longer in the afternoon, due to the west-facing panels. These are connected to a 6000 W single-phase SolarEdge inverter. I asked for an inverter of higher capacity in case I ever wanted to add a few more panels.

Actually, the system isn’t complete yet, as we’ve got a Tesla Powerwall on order (on backorder, like everything else Tesla makes 😉 ) but telemetry from Southern Energy is that we’ll get it in August, so that’s at least on the roadmap. The Powerwall is an important part of the installation as the local utility does not offer “Net Metering.” This is the arrangement with your utility where you can sent your generated but unused power to the grid and you receive payment for each kWh that you send to the grid. So, we have to use all the power we generate, or it evaporates. That’s where the Powerwall comes in. It has a 13.5 kWh capacity, and absorbs power when you are not using it in the house. The solar system feeds the Powerwall, and the Powerwall then supplies current to the house at 5 kW continuous, 7 kW peak. It will supply power when the sun is down, or if a cloud passes over when a large load comes online. This should enable self-consumption of most of the power generated by the panels.

Currently, we’d be wasting a lot of potential power without being smart about when to run various appliances. For example, run the washing machine, dryer, and dishwasher between 10 and 4 (DST). Take showers mid-day as well, as the water heater is a big power draw. But the big thing is to intelligently manage charging of the electric car. It can hold 60 kWh of power, far more than can be generated, and can accept a charge at up to 7.2 kW. However, the JuiceBox Pro 40 EVSE we have for charging can set various charge rates below its 10 kW maximum, and by spreading the charge out during the sunny part of the day (when you don’t have to charge fast), you can capture much more of the solar power. Here’s a graph that shows this clearly. The JuiceBox is set to charge at a maximum of 3.6 kW.

The large “flat” peak is the car charge from about 0930 to 1530, for about 6 hours at 3.6 kW, or around 21-22 kW of demand. Note, however, that the system peaked at about 3.6 kW for only a short while at “noon” (1 PM DST). The demand from the car, combined with the baseline load of about .5 kW was more than the power that could be generated. The sharp peaks are the water heater, or at 0800 coffee and breakfast, and at 1730, cooking dinner. However, the solar still covered 54% of the house demand, and captured nearly 24 kWh. The Powerwall will work in the same way, capturing power left on the table to cover the overnight hours you can see on each side of the graph. We don’t charge the car every day, and this is where the automatic charge of the Powerwall will be very helpful. Without charging the car, usage that would be covered is more like 5-8 kWh. This, of course, is in a shoulder season without the heat pumps running, and we’ll see how that impacts overall consumption. The Powerwall, however, will ensure that we grab at least 20 kWh or so each day when the sun is shining.

Stay tuned for future analysis once we get the Powerwall in place. It’s really interesting to see how you use your electricity, and it can prompt changes in behavior.

Universal remote control

When I did a Facebook post on this topic a couple days ago, I promised to write it up a bit more thoroughly. So, if you read the FB post, you can skip this, or not. 😉

The entertainment systems I’ve cobbled together over time have worked, but only with directions written and taped to the bottom of of the 4 remotes on the end table. Needless to say, it’s not been a recipe for marital harmony. Let’s just say that I have a higher tolerance for a multi-remote control system than my dear wife!

This year in early March, one of my sons (who is more of a geek than me) suggested after a visit that it was too complicated and he agreed with his mother. He showed me a high end version of a Logitech remote, but I just couldn’t hang with the $250 price for something I was sure would not work. Not much happened until I was headed to a conference for a few days…and it was made clear to me that something needed to be simplified!

So, when I returned I looked again at the Logitech remotes and saw that there was a simpler version without a touchscreen remote. I ordered the Harmony Companion, and it brought harmony to the house!

It truly works! I set up 5 different programs – one to set up for music streaming from Alexa, one for the TV (we use an LG TV, OTA programming, and a TiVo), one for AppleTV, and two for Roku, one to launch HBO Now, and one to launch Amazon Prime. I have a Chromecast also in the Denon receiver (actually, I have three of them all in different TVs), but never use it so no program yet for that.

Programming the remote involves a set of “activities,” which are multidevice sequences of actions to set the stage for the activity. You can control lights, etc as a part of an activity if you have compatible tech, but my Smartlife WiFi outlet sockets don’t work with it. It does apparently support and understand remote commands for just about any device with a remote control.

I did my setup on my iPad, and apparently that’s easier than the computer-based setup per the reviews. The UI allows you to select devices and actions as a part of the activity. The problem is that it doesn’t allow you to delete or move a step, though can add or modify a step. My TV sequence involved a bit of tweaking as when you turn on the TiVo and TV, the TV doesn’t sync to the HDMI input unless you do another source switch a few seconds later. So I had to turn on the TV, the receiver, the TiVo (with a different source), the delay several seconds (there is a delay command for just this type of situation), and then switch to the TiVo input. The iPad app crashed several times while I was doing the activity setup; it’s the weakest part of the system.

I also set up the Alexa skill and sync’d the accounts. This is another area that doesn’t provide as much control as I’d like. When you set it up, you get to choose keywords used in the invocation, but there’s no way to edit this after setup, at least that I’ve found. It also takes a few minutes for the accounts to sync. But it works! “Alexa, turn on the TV” does so, and “Alexa, turn on Tunes” sets up things for Alexa to use the receiver. With the TV and other such activities, you can also tell Alexa to “turn up the volume on the TV” and it will adjust the receiver volume setting.

The Companion remote has three activity buttons, shown as “music,” “TV,” and “movies” but using icons. You can short press or long press the button and that will give six activity invocations.

The remote talks to the base with Bluetooth, and the base emits IR/RF/Bluetooth to control devices. Per the directions, you can place the base with other components , and the IR reflects off the room and does not have to point to the targets.

So, this really does work. This particular version controls up to 8 devices. It sells for $100-$130 and has brought “harmony” to my house!