It’s April 22nd, which means it’s Earth Day! I thought in honor of the day, I’d revive an old topic I wrote about some years ago and provide an update about how things have gone since then.
Back in 2011 I stared developing plans for building a micro photovoltaic power station. I wanted something that would be reasonably compact, semi portable and capable of providing a few hundred watts of 120V AC power. Looking back it’s amazing to see how long I had been developing my idea. I built several 10-15 watt prototypes. For those I built my own controllers and regulators.
After I became more confident with how things worked and what was going to work and what wouldn’t, I started drafting plans for my full-size power station. Around February of 2014 I finally pulled the trigger and placed an order for all of my carefully chosen components. I ended up deciding on a 50-watt polycrystalline panel, Genasun 5A MPPT controller, Concorde Sun Xtender 34 amp hour AGM battery, and a Samlex 300-watt pure sine wave inverter. The system was small enough that it was kind of overkill to have detailed monitoring, but I chose to use a Bogart Engineering Trimetric 2025 to monitor everything.
Over time I cleaned up the system, mounted everything to a relatively portable board and stored it in my apartment connected to the panel which I mounted outside. It’s been two years, so what have I learned?
- I learned that AGM batteries are really nice, but they’re not indestructible. During my first year, I relied on the station very heavily. I would often dip pretty far into the battery’s reserves, though never more than 50%. Still, doing this consistently, and struggling to keep it charged properly in the winter months meant that after a year the battery wasn’t able to maintain voltage under load anymore. In March of 2015, I replaced the 34-AH battery with a 42-AH battery from the same manufacturer. I’ve been much more meticulous about keeping that battery charged properly and it’s still running very well a year later. I use my Trimetric meter to automatically warn me if the charge condition that I set for the battery has not been met in more than 48 hours.
- I also learned just how much it was possible to rely on my power station for every day things. Currently, my AppleTV (3rd generation), iPad Air, and iPhone 6 are all powered pretty much exclusively by the station. I can do that year round. In the summer, I’m able to add on things like my floor lamp, my MacBook Air, 27-inch display, and a fan to cool off. I could probably run all those things for 2-3 hours without dipping into deep battery reserves and 4-5 hours if I really had to. Apple’s notebook computers are very power efficient, and the MacBook Air is one of the most power efficient. That was a major factor in my decision to buy it over a MacBook Pro.
- I’ve become extremely aware of how much power things consume, even in every day life. I’ll often just think of some thing and I automatically think, “Could my system power this?” 300 watts is actually a lot. It’s enough to power most desktop computers, virtually all laptops, certain heating pads, fans, and more, but some things we use casually take a TON of power. Hair dryers (over 1000 watts generally), clothes irons (over 1000 watts) and pretty much anything with a heating element use way more power than I can generate.
So as we get further into 2016 I’m excited for yet another summer with my power station. I don’t have any upgrades in mind. I had always considered adding more generating capacity, but that would make my little system a bit too large. I think it’s a good size right now.
Happy Earth Day!