Archive for Electronics

Solar Nerdiness

So as mentioned I have been pretty nerdy about this whole solar thing. I am logging as I go as well as jotting down useful things as I learn them. Actually getting up and running was really easy, fine tuning is a bit trickier, and actually understanding what is going on is downright fiddly.

My initial solar panel is a Coleman 18watt (1.2 amps at 15 volts). A basic little thing with very plug and play wiring. I am using the 7amp charge controller that came with it. The charge controller can theoretically handle another four of these panels before I would outgrow it but I have no idea if it is actually that robust. It does seem to be doing its job though so I’ll keep using it until I find out otherwise… or it explodes for some reason.

The charge controller has a 13 volt cut-in. If I understand correctly this means that no charging takes place unless there is at least 13 volts coming from the panel. My guess is that this is because trying to charge a 12 volt battery with 9 volts would be useless if not actually detrimental… but I have no facts to back up that thought as of yet. It also has a cut-out of 14.25 volts… If this means it refuses to charge if the panel is operating at its theoretical maximum then this could be a little troubling come summer… But I am sure there are very good reasons for it.

The Panel and controller are feeding in to a 12 volt deep cycle marine battery from Rural King… I don’t really know anything useful about the battery but assume its about 45 amp hours… it was cheap. I keep forgetting to actually write down the model number and research it.

Coming out of that is a Microsolar 300 watt pure sine wave inverter. I understand that inverters eat a lot of power converting 12 volt to 110 volts, but I haven’t really dug deep enough for an easy way to run my modem and router directly off of 12 volts yet. I can get a 12 volt power supply for my current laptop, but I am running it mostly off of its battery at this point to try to get as much online time as possible. Plus I’ll want to eventually run some lighting as well so the inverter stays.

In theory it should give a warning alarm when voltage starts to get low, then another alarm as it shuts off. In practice it skips the first alarm entirely and just goes right to the shutdown and at some rather wildly different voltage levels that seem really high (over 11 volts). For now I am chalking it up to just being a pretty cheap unit, but I’m keeping my eye on it and almost certainly it is just a starting point until I can afford something serious.

My main measurement device at the moment is a little volt meter I got from radio shack sometime in the last decade. I really need to add a Kill-A-Watt or similar device and maybe start recording temperatures as well.

That’s enough nerdsplosion for now. If you are one of the four people who are actually curious about this then there will be more to come. And if you are one of the two people who Know Relevant Things, please feel free to comment here or in FriendBookFaceSpace and tell me everything I am blatantly overlooking.


The power of the sun!

So as of a few days ago I have harnessed the power of the sun for my own purposes.

At the moment the system consists of an 18 watt solar panel, the cheapest charge controller on the planet, the cheapest deep cycle marine battery I could find, and a 300 watt pure sine wave inverter.

I have been keeping very nerdy notes and tracking how it does for a few days and I am a little disappointed. A full day of charging got me about four hours of power running my modem, router, and a laptop… The battery never charged past 11.66 volts. This is probably pretty good for such a minimal setup in the winter, but I hoped for more. In the near future I hope to add another solar panel which will, in theory, get me up to a full 12 volts much faster. I am kind of seat-of-my-pants learning this as I go and it’s a lot of fun.

More as things develop with lots of really nerdy numbers.