Disaster Preparedness with a Prius

by Ben N on December 31, 2017

1,000 watt inverter in a Prius

I commonly get questions about battery backups, generators, solar panels, and other provisions which might be useful for disaster preparedness.

There were plenty of disaster-related comments on social media at the end of September, due to Hurricane Maria hitting the coastline of the United States.

And while most of us enjoy fantastic electric service on the U.S. Mainland, RIGHT NOW, there are STILL places in Puerto Rico either without power, or only intermittent electric service.

My friend, Jomel, lives in Puerto Rico. Today, he posted to Facebook about using his Prius as a backup source of power. The original post was in Spanish, but Jomel was kind enough to give me an English translation, which I’ll post here. He also gives a more concise description of how to use a Prius as a backup generator than I ever could.

“Here we go again, no electrical service since yesterday December 30, 2017 at 9:00 am, so I will celebrate the New Year using the Prius. At this moment I have consumed 2.0 kWh in 7 hours and 40 minutes and the engine has consumed 0.68 gallons of gas, equivalent to 0.0887 gallons per hour.

I connected a 1000 watt Xantrex the true sine wave inverter to the auxiliary battery of the Prius. That’s a 12 volt battery that is been charged by the 200 volt traction battery via a DC to DC converter.

The engine doesn’t has to be running all the time. In my case, I leave the car in the Ready Mode, in Parking with the A/C Off and windows down for air circulation.

The engine runs for 2 minutes to recharge the traction battery and then stops for about 30 minutes, so in an hour it only runs for about 4 – 6 minutes. It’s a very practical setup since it maximizes the engine utilization, and it only runs at about 1200 RPM.”

 

One big advantage of using a hybrid car as a generator is that the engine doesn’t have to run continuously. That saves on noise and exhaust. A car with an even larger battery, such as a Chevy Volt would be able to run an inverter for a significant amount of time before the engine would need to activate. Battery Electric Vehicles would have an even larger reserve of power, but would not be ideal for long-term power outages, as they also need to recharge from an electric source. I’m sure we’ll see dedicated DC solar charging in the future. For now, solar charging is left to the hobbyists and smaller projects. A few years ago, I did power my entire house directly from my Electric Motorcycle. It was also configured to be able to recharge from a single 96 cell solar module.

Disaster preparedness could be as simple as using the car and other equipment you already have. Just make sure to have an inverter that can be connected to the battery. At 1,000 watts, that’s enough power to run a refrigerator, LED lights, a radio or television, and charge cells phones. A simple extension cord can be used to route power to wherever you need it to go. For people living in areas prone to power failures, they could even wire up their homes with a generator input and manual transfer switch.

I followed up with Jomel about the current status of electricity in Puerto Rico, and this is what he had to say:

“The electric power has always been very unreliable, the grid was very old and vulnerable. After Hirricane Maria, all the system collapsed leaving 100% of the island without power. At this moment only about 60% of the people have power. Some experts say that some people may be without power until June 2018.”

 

You can certainly see why Jomel has been installing solar panels for a battery-based system.

Levels of disaster preparedness vary depending on your personal situation. Public infrastructure and support certainly varies. Make sure to be ready with works for you!

-Ben Nelson

Special thank you to Jomel Maldonado for sharing his info and photographs!

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Snow Rake for Solar Panels

by Ben N on December 11, 2017

A few days ago, we got the first snow storm of the year. Not a big deal, but that was the first snow we had since I installed the solar array on my garage. I found that using a broom, even from a ladder, I could only clear the lowest of the three rows of panels.

After reading through a number of web pages, it looked like the most common way that people remove snow from their panels is with a roof rake. So, I found one at reasonable price and ordered it.

Last night, we got another dusting of snow, and as luck would have it, my roof rake showed up as well! It’s a SNOWJOE 21-Foot Twist-n-Lock Telescoping Snow Shovel Roof Rake Model RJ204M. Assembly was easy, just pop the plastic blade onto the end of the telescoping pole and screw on two small aluminum braces.

With that, I headed outside to try the roof rake.

Extending the pole is easy, just loosen by twisting, then extending one section of the pole (it’s four sections total) and then twisting again to lock it down.

IMG_7503At full length, the pole does flex quite a bit. The rake end kind of bounces, but it still feels pretty solid. I had the right amount of reach to get all the way to the top of the second row of panels, and that was WITHOUT a ladder! I could get part of the bottom of the third row of panels, but only if fully extended and with me right next to the building. At that point, I couldn’t actually see up the roof and had to guess at where the rake had landed!

I was hoping that if I could get at least part of the third row of panels that perhaps it would allow the sun to warm the panel and have the snow start to slide down. Although it didn’t get sunny today, it did get a degree or two above freezing for a while. Sure enough, the snow on the top row of panels DID slide down a bit, but not off the roof. Actually, it was almost worse. With the snow covering HALF a panel in the upper row and the middle row, I likely got LESS energy production than if the top row was completely covered and the middle row completely bare!

Using the roof rake is a bit of a workout. Anytime a person is working over their head, it’s always a bit tiring. To me, it felt like a deltoid workout not unlike paddling a kayak. (An like paddling a kayak, NOT something I do every day!) The roof rake itself isnt’ that heavy, (4.8lbs./2.2kg) but with it fully extended, it’s a handful!

Overall, the roof-rake does a pretty good job of clearing the snow from the solar panels. Good, but not perfect. I found that it got caught pretty easily on the mid-clamps that hold down the solar panels. It could also get caught in the gap that separates the rows of panels, although approaching at an angle seemed to help with that issue. A foam or squeegee head might run over the mid-clamps better, but might not bite into the snow as well.

IMG_7506It was also difficult to completely clear the snow. Seemed like there was always a little bit here and a little bit there. Even small amounts of shading on a solar panel can dramatically reduce energy production, so that’s not ideal. On the other hand, if the sun ever DOES come out, those small bits of snow should melt quickly. That’s the one last thing that I’ve been noticing so far with snow and solar panels – of course snow on the solar panels blocks light, but just HOW CLOUDY it’s been seems to have an ever larger impact on the power made.

That is to say that even though the snow is covering the panels, there’s just NOT that much light to convert to energy anyways! In my area, this is an extrememly dreary and gray time of year. Now, if it was SUNNY and the panels were covered in snow, THAT would be a different story!

For now, using a roof rake to clear snow off the panels seems like a simple and practical solution. It’s not perfect, and I certainly wish I could more easily reach that third row of panels, but for now, it’s more than good enough.

Until next time, stay charged up!
-Ben

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Snow-cover on my Solar Panels!

by Ben N on December 9, 2017

I woke up this morning to a gray half-light, and a blanket of snow covering everything…. including my solar panels!

Hmmm. What would this do to my solar power production? To find out, I thought I would clear the snow off as many of the panels as I could and see what the difference would be.

For starters, the bottom edge of the solar panels is about 9 feet high. I reached up with a push broom, but could only clear the very bottom of the lowest row of panels. So, I got out my 8-foot step ladder. On level ground, the ladder is sturdy and solid, and every bit as safe as it would be in summer, as long as I’m careful about my footing. From the ladder, I was able to reach the entire bottom row of solar panels, although I did have to move the ladder quite a bit.

Once I did that, I headed back into the house to check the web interface for my solar panel production. Essentially, the panels with the snow on them were blacked-out, although I was surprised that they DO still make power, just almost nothing compared to the uncovered solar panels.

By around mid-day, there was a little more light, though it was still far from being a sunny day. I’ll have to keep an eye on the panels and see how warm it has to be before the snow can slide off. A few solar friends of mine have extendable snow rake poles which they like. I’m pretty sure I’ll be investing in one in the future.

For now, we’ll see how long that snow stays up there. Based on how much power I create from the one exposed row of panels, I should be able to figure out how much power I “lost” from the others being snow-covered. Heck, I could probably figure out the exact monetary value of what that snow-cover cost me! That snow-rake will probably take some time to pay for itself….

Until next time, stay charged up!

-Ben

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Solar Shading

by Ben N on December 6, 2017

A few weeks ago, I started noticing a shadow creeping up to the solar panels on my garage. Sure enough, in winter the sun would be low enough in the sky for the shadow of a pine tree in my front yard to start blocking solar panels!

What’s a person to do?! Well, other than cutting down trees, (which I also did) the best thing is to PLAN AHEAD!

IMG_7339That started with me originally doing a Site Survey and figuring out how good of a location this would be for solar panels in the first place. Before I even rebuilt the new garage, I was already planning for the solar and used a “Solar Pathfinder” tool to see how much of the garage would be shaded, and at what times in the year. The Solar Pathfinder is essentially a curved plastic dome with a solar chart on a piece of paper below the dome. Looking at the reflection in the dome (sort of like a security mirror) a person can see trees, buildings, and other obstructions that would shade the solar location. Those can then be traced onto the slip of paper, and a little math can be done to figure out what percent of total solar production would be knocked down by the shading.

IMG_7309I knew that one issue with where my garage was is the fact that I have a narrow north-south facing property, and my neighbor has the property line planted with mature Maple trees. Those help keep my house a little cooler on hot summer afternoons, but they also cast a huge late afternoon shadow over my garage. Likewise, in the winter, with the extra-low sun in the sky the shadow of a tree in my front yard may actually be long enough to start blocking out the bottom row of my solar panels. And that’s exactly what I started seeing recently.

IMG_4271So, when I designed the solar array, I planned on using MICRO-INVERTERS. A micro-inverter is a relatively small device which mounts behind a solar panel and converts the DC power of the panel directly to AC power. That AC power is then combined with that created by the other panels, and routed to my breaker panel in the garage. Each panel produces power independent of the others. By contrast, a traditional “Series-String” inverter has many solar panels connected in series, one to the next to the next, and then to the inverter to be converted to AC power. One problem with that design is that a shadow over part of just one panel will reduce the amount of power made by ALL the panels in that string. Imagine the old Christmas lights where when one bulb would go out, they all go out. Only in this case, if one panel isn’t producing power, none of them do. Because of that, even a small amount of shading can have LARGE consequences in terms of photovoltaic energy production.

Another nice feature of using micro-inverters is that the system can provide information about each individual solar panel! Now that’s actually far more information than anybody would want to look at on a daily basis, but it’s very nice to have access to for things like troubleshooting. I’m using Enphase brand micro-inverters and can access all of the data about the panels and micro-inverters through a web page interface. It also allows me to give public access to a streamlined version of that information. If you want to see what my solar panels are doing right now, you can take a look at: https://enlighten.enphaseenergy.com/p…

Looking at the “Enlighten” software graphical interface, it’s very interesting to see how the pine tree shadow sweeps across the bottom row of solar panels. But the best part is that it’s ONLY that one or two panels that takes a hit to power production. Any panel not shaded is completely uneffected.

PineTreeShadingDec2017I also used the software to run an animation of the solar panels late in the day during the summer. Sure enough, it’s very easy to see the shade of my neighbor’s leafed-out Maple trees sweep across the solar array. However, the panels on the east side of the garage just keep producing power, even while the ones on the west side of the garage are shaded. This gives the more easterly panels up to another hour and a half of production time. All that time adds up when it comes to producing energy, and keeping my electric bill low (or NEGATIVE all summer!)

The graphing features in the micro-inverter web display are also interesting. Looking at a week in summer versus a week in winter, I can see how skinny the curves are on winter days. I can also see how the production curve of a typical day is steeper in the PM than the AM. That’s because of that late afternoon shading. However, I’d still much rather have solar panels than not, even if my solar access isn’t perfect!

If you have a location that might be good, but not perfect, for solar production, don’t let it stop you. Tricks like using micro-inverters can help maximize solar resources. That doesn’t mean you don’t do your homework or put panels just anywhere. Careful planning, researching solar, and using tools like a Solar Pathfinder can allow you maximize your resource and start making renewable energy!

Until next time, stay charged up!

PS: In the video, there’s a number of times where I use the terms “Power” and “Energy” almost interchangeably. To be clear, the two are different. Power is how much work is being done right now, whereas Energy is a total amount of power over some unit of time, typically an hour. Power measured in Watts (W) or Kilowatts (kW) and energy usually in Kilowatt-Hours (kWh). Think of it this way, an old fashioned light bulb might use 60 watts of POWER. You will use it for some number of hours over a month, and you will get an electric bill for your ENERGY use in kWh.

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Gen 2 Flux Mopeds DIY Special

by Ben N on December 2, 2017

Recently, I’ve had a fair number of people asking me about electric scooters.

Not only are scooters fun to ride, but you don’t need a motorcycle license, and they are often cheaper to insure and title.

That’s why I was excited to recently hear from Matt at Flux Mopeds. A while back, they had a few of their scooters available for sale, but WITHOUT battery packs. For anyone who could build their own battery pack, it was a great, inexpensive way to get into an all-electric ride without a lot of money. I got one of the scooters and built a pack for it from some Nissan Leaf cell modules I had. Since the scooters were originally designed for a removable pack, they feature a pair of 50A Anderson quick disconnects and DC circuit breakers, making connecting your own pack very simple.

Here’s a playlist of videos from working on one of those scooters:

So now, Flux again has a few of their scooters available, sans battery, as a DIY special. These are now the Second Generation EM1 mopeds. The second gen features a Sabvoton brushless DC sine wave controller.If you can assemble your own pack, you can get a great deal on an electric ride. They are only charging $730 each. These are BRAND-NEW, with a real VIN, all ready for street-legal riding EXCEPT for the battery. Buy two or more and they are only $680 each!
Visit http://www.fluxmopeds.com/innovators for more information. If you are interested contact Matt at mjbrueggeman@fluxmopeds.com

Get them while you can, and tell them Ben sent ya!

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