in blue, the curve for a normal day, in red, the moon gets in the way.
The old inverter I bought second hand for $20 bit the dust. In part due to my lack of cable strain relief which created contact between ground and negative, oops :\ lessons learned. I bought this new guy which works so much better I think the old one was on the way out anyway. I especially love the fact it comes with a remote start/stop. Since we rarely use 110AC and the solar shed is 50′ from the house, it’s perfect to remove phantom loads. It’s not like we remember to ever turn it off, but we can
We just upgraded our batteries from 3 * 35Ah lead acid (right) to 3 * 155Ah deep cycle AGM (left). The difference is like night and day; pun very much intended. These bears weight 90 lb each. We added lights in the house and are able to make it through several overcast days without loosing power. I still need to wire in another charge controller and clean up the mess of wires in the solar shed. The old system will get re-purposed for raspberry pi instrumentation around the homestead.
The past few weeks have made it clear that out 2 solar panels weren’t enough at all for the Winter months. Short and overcast days weren’t enough to keep the battery charged with even very minimal use and we went dark a couple of days. I don’t have numbers yet but these 3 panels should do a lot better than the 2 I had. I also doubled the batteries’ amp-hours to have more buffer.
This blog is now powered by a Raspberry Pi using 100% solar energy. Nicole instrumented the Phidgets sensors so we would gain some visibility into our electricity production & consumption. This has already given us some great insights. We can see the effect that each device we use has on the system: how much the LED lamps take to charge, the hole that the inverter blasts through the battery when turned on. We can tell that not all sunny days are created equal in their ability to give a charge. We can even tell the increase in electricity consumption that rsyncing a whole bunch of data to the Pi has: 0.03A.
- solar panels volts (a good indicator of sunlight)
- input amps (indicates when the charge controller uses produced electricity)
- output amps / load (what we consume with various devices)
- battery volts (whether this blog will make it through the night or not)
For now I’m only graphing using the Gnuplot one-liner from Hell. More to come…
Charge controller (top), Raspberry Pi (top right), Phidgets interface kit (bellow the pi), Phidgets current sensors (bottom).
My new favorite project screws
The volt-meters (left) aren’t live yet but the amp-meters (bottom) are.
With the inverter hooked up and a properly fused distribution box
The Pi reading its sensors, Nicole is taking on the data aggregation.
The goal is to move Akrin to the Pi to have a solar powered server.
It’s been hard to finally get to wiring what I have for a solar install. I’m still fuzzy on some of the science and I want everything to be perfect for the big launch. Necessity and having all the gear sitting there is making me reconsider. This afternoon I decided to wire the basics and deal with the imperfection.
What we have now are 2 panels in parallel, a charge controller, a 35Ah deep cycle battery and the load. No inverter, no clean wiring, no fancy instrumentation to measure everything.
What this gives us is the ability to use a 12V DC socket and 3 USB ports, even when the sun is not shinning This isn’t much but as I said earlier, when starting from scratch everything is a huge victory. It sounds trivial until you realize how much everything we do now is either 12V DC or USB powered. The charge controller comes with its own USB port with which I tested powering a Raspberry Pi.
I’m so exited about generating my own electricity. Solar is really beautiful, much more so than I thought it would be going in. I’m really amazed that these panels just sit there and make electricity. I’ve always known that but I’m actually using this electricity, I find myself contemplating the system for a lot more than its function. It feels like getting something for nothing, while not burning fossil fuels, while going straight to the source, while being independent, while drinking a beer. I’m a fan.
With a couple of panels given to us and $190 worth of equipment remaining. We should be able to get enough power to keep things charged and and modem running. First housing is needed, I’m green at this and if it’s going to burn down, it won’t take the house with it. This “shed” will also be where the phone line terminates for our internet needs. This way no need to run unsightly wires to the house, and power is right there for the modem.
The research I’ve done shows that there are many ways of doing solar and way too many variables to keep track of. It really seems like everyone has got their own way of going about it. So for now I’m keeping it small and simple, then I’ll develop my own way given our circumstances Who knew “terroir” could be applied to solar energy?