We need more power!

We went through our power needs today. It took us about 1/2 hour or so to write down the power needs for our electrical and convert the results to an amp hour number. We're going to have to make some sacrifices....

Our total power requirements for our family of 4 came out to roughly 120 amp hours per day. We want to have enough power coming in to cover all of our needs and have a bit of a buffer so that if we don't get power for a 2-3 days we don't run the batteries flat.

There are 2 parts to powering our new off the grid lifestyle. The first is getting the power and the second is storing it so we can use it whenever we need it instead of only when it's available.

Today we covered the storage part and bought 880 amp hours (at 6V) of battery storage to add to our roughly 300 amp hours (at 12V) that we already have installed. We'll only use the 300 AH bank in an emergency. We can use roughly 50% of the capacity of the batteries without damaging them, so our effective amp hour bank is about 220 amp hours (440 at 6V, but 220 at 12V). That gives us about 2 days power without any power coming in.

We also made a solar panel and charge controller purchase today. Nobody in our area had anything in stock worth looking at, so we settled on a company in New Mexico that had the best price on solar. After shipping costs, the price still comes out better than buying local and they had one of the panel types I was interested in - a 64 Watt Unisolar panel. While not as high powered as our previous panels, we're hoping to gain a bit longer charge time. Total Amps per panel came out to 3.88 at 16.5 Watts. We could only afford 4 panels, which is a bit shy of our power needs. 4 panels put out 15.52 Amps per hour... If we assume that we'll get roughly 6 hours of power out of the panels then we should expect roughly 93 amp hours out of our panels. It's hard to accurately guesstimate the number of amp hours we'll get during the day bacause the sun follows an arc over the sky and the panels don't, so the voltage out of the panels varies depending on how low in the sky the sun is. There's also some room for error, because if the batteries are fully charged and the sun is still out, we can time some of our usage during that time and get "free" electricity directly from the panels instead of discharging the batteries. Our amp hour usage is based on no sun at all, so some of our hours running the fan or laptop may not pull any power from the batteries depending on how the weather cooperates... At some point we'll need to expand the number of panels we have or find non-electric (or more efficient electrical device) alternatives.