A Solar Website

As if I needed another project, I had been tossing something around lately regarding renewable energy and the web. Low Tech Magazine, which showcases what it considers old and forgotten technology, has an edition of their website available served from a Raspberry Pi run entirely off-grid. Their setup consists of a Pi powered from a solar-charged battery, and they make it a point that depending on weather, that site may not actually be available at all.

I think that this is an interesting concept, although I’ve been tossing around the idea of taking this further. Rather than try to keep a small web server running all the time completely on solar power, what about running it only when the sun is out? In other words, whenever enough sun hits a panel to produce enough power to keep a Raspberry Pi going (about 3 watts, say). With a large panel, this means it could stay up even when it’s cloudy.

I’ve been playing with off-grid solar for years in a hobbyist capacity, and first wondered about this when seeing the green ‘charging’ light on my charge controller turn on even on a clear night with a bright moon. That is, with enough panelage, can a useful amount of power be extracted even in low light? And what ways are there to utilize solar power without trying to store it?

The system, in my mind, would be relatively simple: A photovoltaic panel, one meant for charging a 12 volt battery, would feed a Raspberry Pi via a buck converter. When there’s enough sun to keep the Pi running, it runs. When there isn’t, it shuts down. The converter would help to match the panel’s output to the Pi, supplying it with a constant 5 VDC. With a large enough panel (>20 watts?), it should be able to put out the required 3 or so watts over a range of weather conditions.

I’m wondering about some other bells and whistles, like somehow predicting when night is about to fall, and gracefully shutting down the Pi. And monitoring voltage and current as well. I may take this as an opportunity to design my own buck with some of this built in, but I think an off-the-shelf converter would work as well.

Anyways, I’m not sure when I’ll get to this, but it’s just a thought. I’m not sure how useful it will be, but it could be kind of fun.

An Update

I don’t need to tell you all that it’s been a hell of a year this past year. All I will say is that I’ve had projects that I’ve meant to document, and other content that I’ve wanted to generate for this site, that I’ve been putting off for one reason or another. At leas spammers have found this place, so it’s not completely lonely.

This Site

I set this up with a fresh new WordPress blog, since that’s what I’ve used in the past. WordPress is nice, but it’s a little clunky for a single person blogging. It does make some thing easier for someone who’s not primarily a web developer such as myself, but I’ve considered leaving it for something else.

Static site generators have been kind of interesting to me, since the server just grabbing and sending a bunch of static files has a nice simplicity to it. I can compose in just about any text editor too, which is neat, and while WordPress’s editor is very capable, it’s kind of clunky. In fact, it’s kind of laggy to type in. For the most part, typing in a text editor would probably be more pleasant. But, it’s something to look into, and decide what to use, how to lay the site out, etc.

That said, WordPress itself is powerful, and a great choice for a lot of things. For someone who doesn’t want to mess with setting a site up in too much depth it can be a good move.

Power Converters

I’ve been slowly chipping away at a project to build a buck DC-DC converter, to step between common lead acid battery voltages (12, 24, 36 VDC). Mainly, the goal is just to do it – to gain experience with designing it, laying out the PCB, writing firmware (controlling with a microcontroller!), etc. But I intend to make it part of something bigger.

I had in mind using this converter (and clones of it, when I get it working) to kind of create a DC microgrid – stepping voltage up from one battery, and moving it to a different part of my house to power things or charge another battery. In fact, battery-to-battery charging kind of set this off: In a power failure, I could leave one in my car, step 12 VDC to 36 VDC for a longer wire run, and then back down to 12 VDC in my garage… But with logic to charge a 12 V battery.

Of course, you have to be careful about leaving the car on/draining the battery, and it’s probably not the most efficient use of a car, but for the rare occasion when the power goes out and there’s not enough sun for solar, and I’m running low on power, I think it has merit.

Beyond that, I’d like to explore using this as a sort of maximum power point tracking (MPPT) controller, either from solar panels into a battery, or solar directly into the microgrid. Off-grid solar with no (or with a minimal) battery is kind of an interesting idea to me, and with the right controls it may have potential.


This is a related, but distinct project from the above: a power inverter, to converter 12 VDC (at first) to 120 VAC, with a sine wave output. Not only that, but to go the other way, and rectify it as well to act as a battery charger. This is something I’ve wanted to do for a while, but have mostly just been thinking about aside from the occasional simulation.

Chick Corea

Chick Corea passed away this passed week. I don’t write about music much online, but I am a musician, and am a big fan of his. I’ve seen him live several times, in different configurations, and while up there in age I always imagined he still had years left in him. He will be missed, but his music isn’t going anywhere.