Off-grid Solar Living When There is No Sun

The weather forecast for my area tomorrow is looking pretty ugly! The rain could be starting just about anytime this evening and continuing through the night. At some point Saturday it’s supposed to transition into snow as the precipitation continues unabated into the early hours of Sunday, with as much as 6 inches of the white stuff predicted to accumulate. The catch here is that transition stage where the ice is supposed to come. Lots and lots of ice, freezing rain accumulating to as much as 3/4 inch of ice. It’s the ice that really causes the problems around here. We can generally deal with rain and snow just fine. Should this ice storm come to pass there will probably be lots of downed trees and plenty of people without power tomorrow. Being off-grid and generating all my own power through solar panels, downed power lines aren’t likely to cause me issues. Ironically though it was still looking like I would be powerless during the storm, just for different reasons.

I realized today as I was working to forestall this power issue that despite this blog about my “explorations in art and living” approaching a year old now I haven’t really posted anything about my off-grid photovoltaic solar system. This seems like an opportune time to share a bit about living with such a system.

Actually, I have two separate systems. The metalsmithing studio has had it’s own small array powering it since I built the studio 10+ years ago. It was then almost exactly 7 years ago that I got the large array that powers my home and the rest of the buildings on line and disconnected my homestead from the main power grid. I should sit down and write a post going into further detail about the pros and cons of all this, but tonight is not going to be the night for that. This is just going to be about the current issues with the system.

A nice thing about generating my own power is that I’m generally not at the mercy of fierce storms taking down power lines, leaving me helpless to do much until crews of hardy line workers brave some truly nasty, dangerous conditions to piece by piece rebuild the damaged grid and restore power. The last time power was out for everybody else in my area I didn’t actually notice until hours later when I happened to try going to the store only to find it and everything else closed.

The downside to generating my own power is that when it’s out at my place I am the one responsible for fixing it! Which gets me to my current position, staying powered through the weeks to either side of the winter solstice when the days here in the northern hemisphere are shortest and my specific region gets many severely cloudy, overcast days due to the proximity of Lake Michigan, one of the Great Lakes. (We generally call this lake effect weather.) It’s not at all uncommon during this period for the sun to not show itself fully for many days on end. So just how does one live off-grid with solar power when there is no sun?

First for those who have never worked with solar power I should note that the panels do generate some power even when there is cloud cover, usually even with heavy cloud cover. However, the watts generated are drastically reduced. Today is a fine case in point. My panels are theoretically capable of producing 4400 watts an hour in full sun striking directly perpendicular to the panels. Accounting for the fact that my panels are fixed in position and thus not tracking the sun to keep that perfect angle, on an average day I could get the equivalent of 4 to 5 hours of full, direct sun. This would be between 17,600 to 22,000 watts. More often this would be expressed as 17.6 to 22 KWH. Today has been heavy cloud cover transitioning into a dense fog. To be honest I’m impressed with the amount of power my array generated on this gray day, a whole 500 watts, or .5 KWH! There have been many days with even less.

In order to live through these periods of little to no sun and still maintain power I need to have a battery bank that has stored capacity from brighter times. This is what makes an off-grid system so much more expensive than a system that remains tied to the power grid which can easily feed in more power when needed. It’s also at the core of the issues I was dealing with today. I noted earlier that it’s been almost exactly 7 years since I began using this system and my current battery bank. That also happens to be the average life span of the sort of batteries I’m using in that bank for this type of application.

I have a 48 volt system whose battery bank was comprised of 8 large 12 volt batteries wired together into two parallel sets of 4 batteries connected in series. (Did your eyes glaze over on that? Don’t worry you don’t really need to visualize what I just said.) In the past couple months 4 of those 8 batteries have gone bad, no longer keeping a charge and thus becoming a drag on the entire system. So I have been removing them one by one and rewiring everything to adjust. Now I am down to 4 weak batteries limping along, the bare minimum I need to keep my 48 volt system operative. So I have very little energy storage capacity and I’m still in the period of the year where the days are short and cloudy. This hasn’t been a good combination.

Today I looked and saw the voltage on the batteries was running low, to the point I expected the system to shut down soon, as it does at a certain point in order to protect the batteries from being drawn down too low where significant permanent damage will occur. Looking at the weather report I wasn’t seeing any sun happening today or during the storm tomorrow. That would likely mean I would lose power due to a low battery bank sometime during this period.

I initially tried to get my system built to a size to handle this exact time of the year. It’s no mystery what happens around here about now. It happens every year. This makes my overall system more expensive that it would need to be if I lived in a place that got steady sun year around, such as Arizona for example. I need to get through the time around the winter solstice and then the rest of the year I have way more power than I need. I’ll just say that the “professional” I hired to design and build this system for me did a less than stellar job. I blame myself for being lazy and trusting he knew what he was doing, not learning about and checking all the numbers myself. The system was failing before the county inspectors had even signed off on it. It was an ugly mess I don’t care to get into here, other than to say I worked to fix the system afterward myself by doubling the panel array size and increasing the battery bank to the 8 batteries I mentioned earlier. This is still undersized for the serious cloud cover that happens here in one of the worst areas in the country to do off-grid photovoltaic solar.

I contemplated getting even more batteries, but kept choking on the price, esp. since I really just needed the larger storage bank for about 6 weeks out of the year. In the end I opted to get a small generator which I could use to charge up the batteries should there not be enough sunny days at the right times. In truth I think everyone who does run off-grid probably wants to have such a generator as a back up plan. It’s just a good idea.

So anyway, seeing that I was likely to lose power tomorrow during the storm I decided to get ahead of things and run the generator today instead while the wind, rain, snow, and ice aren’t flying about madly. That way tomorrow I can stay huddled up warm, comfy, and electrified inside as the winds howl outside.

Thus while the generator was running I realized I should share some of this with you all. When getting the generator I contemplated just what type to get. Gas powered is probably the most common. I decided to go with a propane generator though. My thinking was that since I use propane for annealing in my studio I would have the tanks around already. Not only that, as far as I know propane doesn’t really go bad if it sits in the tank for years on end. My hope was that I wouldn’t need to use the generator often at all. Some years I haven’t needed it. Other years I’ve used it couple times. This infrequent use is why I didn’t want to go with a gasoline powered model. Gas can go bad if it’s just sitting around, and any gas I’d have on hand for the generator would just be sitting since I don’t use gas powered lawn mowers, chainsaws, or other such things. Granted I could have tried to set up a system where at some point I’d pour the gas into the car before it got too old, but I somehow know this would be a point of failure for me.

So propane it was. I shopped around and got one for about $400 if I remember correctly from the local farm supply store. The first time I used it though a very weird thing happened which I wanted to share for those of you who don’t know about this. It left me absolutely baffled at first. The generator would start right up and run beautifully for a few hours, then long before the tank of propane should be running empty it would start running really rough, choke off, and shut down. I notice ice crystals forming on the tank, but it was cold out so I didn’t think much of that at first. The tank still felt full, but I couldn’t get the generator to start up again. I swapped to another tank I had on hand and again it ran fine for a while before shutting off in the same way. What was going on?

After doing a bit of online research I learned that at a certain point propane can get too cold to allow the liquid to “boil” into the gaseous state that the generator was using. While it wasn’t anywhere near that cold out, the generator was drawing propane out of the tank at a fast enough rate which had an effect of cooling the tank and its remaining propane down even more than the outside air temperature. Eventually it would get to the point where the gas was no longer being formed from the remaining propane!

Now that icy frost on the propane tank made sense. By looking at where the line of ice was I could see what level the remaining propane was at, however, it also indicated I wasn’t going to be using that until the tank warmed up again. My solution has been to keep a couple tanks on hand at all times so I can just swap them out as needed, letting one warm up while the other is being drawn down. It also seems to run longer when the tank is full than when it’s running low. My guess here is that the greater mass of a full tank means it cools off slower. This is also probably why I’ve never had this issue with the big 500 gallon propane tank that fuels my home furnace (which I rarely use now that I have the RMH) and stove.

So if you find yourself wanting a generator and debating between gasoline and propane powered ones this is something you might want to keep in mind should you live in a cold climate. On the whole I think I would still choose propane were I to do it again. If tomorrow’s storm does cause wide ranging and longer term power outages my neighbors with gasoline generators may run into issues keeping them fueled should the gas stations lose power to run their pumps. I, however, could still do a propane tank swap if need be.

Though I haven’t said it yet, the first way to help deal with days of minimal solar power generation is to cut way back on power usage during these times. Before I ever got the solar array my first task was to get my normal usage way down below the average American household so I wouldn’t need a huge system to power my needs (or should I say desires). At the time I was averaging 60 to 100 KWH a month. You can check your own power bill to see what your household uses, but I recall reading at the time the average was about 800 KWH. I don’t really know what I use now, since I don’t have an actual meter recording what is used. I do know I’ve found ways to lower it even more during this Solstice time of the year. At other times I use a lot more simply because it is available and would go to waste otherwise. For example, on sunny days in the spring and fall I can heat my home with power sucking electric space heaters!

As a bit of a side note to this post I wanted to note a money saving tip. I really hate shopping around, comparing prices, features, etc. trying to figure out just what the best overall deal is. It annoys me. However, when it comes to major purchases like say, a solar battery bank, it is well worth the time. I spent a few hours digging around, considering various new battery technologies, price shopping, and so on. In the end I decided to stick with the same AGM lead acid type batteries I’ve been using. There are other types of batteries that should last longer and thus be lower in total life costs, despite being much more expensive up front, but I’m hoping battery technology will get even better and costs will come down lower during the life of my new set, esp. as electric car production is ramping up. So I’m going to take a bit of a gamble and wait.

Once I decided on the AGM type I still spent more time than I’d like shopping around. I found I could get the same brand from the same retailer as my current batteries for just under $5000 at full price. I know though that they will deal when you are buying larger quantities. Actually, I think they are more like car salesmen where the price is always a bit negotiable. Anyway, I stopped into the store while I was already in the area and inquired. They gave me a price of $4000 plus tax (another $240). That’s a significant difference. Still I found a different brand of the same type battery at a solar supplier in AZ. They were offering free shipping if the total was over $3000, and they had a special for the month of 6% off, plus they weren’t adding on a core charge (which was $72 per battery for the local place). I ended up getting those for just over $3400 shipped. There’s a decent chance I can recoup a core charge on the 8 dead batteries I have here too. If I’m able to get the full $72 that is now charged on new ones that would be an extra $576 in my pocket bringing my final cost down to just over $2800. So as much as I hate shopping around those few hours of work will end up saving me a couple thousand dollars! That’s a pay rate of several hundred dollars per hour! I don’t know about you, but that’s way more than I generally make. Shopping around for big ticket items can really pay off, helping me substantially toward my goal of financial independence.

Studio Snippet

One of the routine things that happens in my studio is a group of vessels being raised. I’m usually actively raising about 6 at a time. These are the current 6. I’ve found that if I do this sort of heavy hammering on a regular basis, but only for a couple hours a day, then my arm and wrist muscles stay in shape but don’t get overworked. So most days I will begin my workday with a bit of raising. Then I move on to lighter duty chasing or business stuff for the rest of the day.

I’m happy to have a site where I can again allow comments. (I had to shut them off on my main website because the spam was simply uncontrollable!) So please I encourage you to share thoughts of your own. My general rule about comments though is just to play nice. Differing views are fine, but I’m not interested in engaging in or moderating verbal fights. If I feel things get out of hand, by whatever criteria I decide, I’ll just start blocking or deleting things.