Today, I was up at 4 AM for work and had a short day. As I was driving back home mid-morning, I noticed the roads were wet. We had a thunderstorm roll through my neighborhood while I wasn’t there. I saw a power utility truck at the transformer just past my backyard. It didn’t take me too long to realize that we were in a BLACKOUT! What did that mean for my SOLAR!?
Let me first say that this is RARE. I can’t remember the last time we had a blackout, other than the odd power hiccup of the power being out for ten seconds or less. (EDIT: The last time we had a blackout was five years ago. I specifically remember it because that summer was a crazy heat wave and I powered my house from my electric motorcycle. Here’s how I did it: Motorcycle Power Backup Link)
The other thing is that a blackout usually isn’t really a big deal. I have windows and skylights at my house, so electric lights aren’t even needed. At this time of year, it’s light at 5 AM and doesn’t get dark until after 9 PM.
I checked my power meter, which is digital, and saw that the display was blank. We had NO power. Of course, that means that my micro-inverters don’t produce power either! I also checked my AC disconnect. It was still in the on position. I thought that perhaps because my system is SO NEW, and a utility electrician was literally working right in my back yard, that perhaps he would have come over and thrown the switch to off. (Unnecessary, of course.)
Grid-tie inverters (including the micro-inverters I’m using) automatically disconnect the solar panels from the grid in the event of a power failure, or even if the voltage or frequency of the grid power is out of spec, such as in a brown-out situation. The micro-inverters are under each solar panel on the roof, so even if I wanted to, there’s no way to unplug the inverters from the solar panels and connect the solar panels to something else, like a DC battery charger.
Grid-tie inverters do NOT let you make power when the grid is down. This is commonly considered the biggest draw-back to this style of photo-voltaic system. There are also “hybrid” systems, which combine grid-tie and battery backup, but they are less efficient, and more expensive and complex. There is also another setup which I think is very clever. SMA Sunny Boy grid-tie inverters have available a “Secure Power” outlet. They are grid-tie systems, but in event of a power failure, the solar panels (during daylight) will still provide AC power to one electric outlet directly off the inverter. That’s one AC circuit, enough to run an extension cord to a refrigerator, a radio, and a few lights. That’s the system I would have chosen if I hadn’t gone with the micro-inverters..
So, how did the blackout effect me?
Well, pretty much not at all.
I used my battery-powered smart phone to communicate with the internet and could pull up my solar production information, including seeing that there WAS NO power being produced at that moment.
I was also hungry and was planning on making some coffee. Making a sandwich doesn’t exactly require electricity. On the other hand, I usually use an electric coffee pot, but without power I instead put the tea kettle on the range and match-lit the natural gas. Even without power, I can pan fry or boil water, I just can’t use the “spark-start” on the range. (The natural gas oven will not work in a blackout as it uses an electric glow bar.) In the winter, I also have my wood-stove not just as backup heat, but also available for cooking. I used my wife’s French Press to make the coffee.
I also have some battery equipment that is NOT RELATED to the solar system. Specifically my electric car AND an electric riding lawn mower.
My lawn tractor is a GE Electrak. These were made in the 1970’s and basically have an electric golf cart driveline. They are typically powered by six 6-volt batteries for a 36VDC system. I recently purchased some ElecTrak equipment from a friend, including a power inverter designed to run off the lawn tractor. If I wanted to, I could run an extension cord from my lawn tractor to my refrigerator or other electrical equipment.
I also have a Mitsubishi iMiEV electric car. It would be pretty easy to connect a 12V power inverter to the plug in the car. The car has a 16 kWh battery, but was at only about half charge when I got home. Even so, 8 kWh of energy is quite a bit to just run some basic power equipment.
Perhaps what’s most interesting is that just moments before I shot the cell-phone video of me talking about all this, the power came back on. I had only been home about 10 minutes total.
I could have spent thousands of dollars on a battery-based system to go with my solar panels. Perhaps if I lived further out in the country or otherwise in an area prone to common or long-duration power failures, I would have. As it is, a simple grid-tie system is the least expensive, lowest maintenance renewable energy system a person can get.
SHOULD I want something else available to me for blackouts, I still have it. Besides the batteries in the car and the tractor, I also still have the 400 watt solar panel on the Solar Swing Set. I was planning on rigging that back up to a basic DIY 48V battery system. I have no urge to run out and buy a Tesla PowerWall or any other similar system.
As I type this, I double-checked my solar panel power production. The solar panels are making power, although it’s an overcast day, so they are NOT making as much power as they could. Using the Enphase software, I could view when and how long the black-out lasted. It was 50 minutes. Looks like solar power would have been about 3 kWh during that time, so I probably missed out on producing about 39 cents worth of electricity.
Keep in mind that blackouts in my area usually happen at night or during very stormy weather. At night, the solar panels will produce no power, and during clouds and rain, PV production would be minimal. In essence, when I have a blackout, solar panels wouldn’t do me any good even if I DID have them connected to a battery system.
Would a battery-based Photovoltaic system be the right thing for you? I don’t know, that’s for you to decide. If you live in an area with unreliable grid power, and the power is out during nice sunny days, it might make the most sense. Everyone’s situation is a little different.
As for me, I’m glad I went with a straight-up grid-tie system, even if it doesn’t produce power during a blackout.
Until next time, stay charged up! (Especially during a blackout!)
-Ben
P.S. Here are some of my previous experiments with solar and battery backups.
http://www.instructables.com/id/Poor-Mans-Smart-Grid-Blackout-Protection-by-UPS-/
http://www.instructables.com/id/Solar-Swing-Set-PV-Playhouse/
