As I sit here at my desk, typing away, I keep one eye on a tab in the browser. The tab is the wireless window into the current state of my power system. Right now, I notice that the current state of the batteries is 52.8 volts and the State of Charge is 99%. We're only using 370 watts at the moment: not too many lights and my computer are the only draws. In a few minutes, however, the outside lights will come on and we'll start getting dinner ready. The usage will go up to around 1.3 kW. We store about 32 usable kW. As we use the battery, the voltage falls, and if the voltage falls below 40 volts, the inverters will shut down to protect themselves. At that point, unless I have an alternate source of power, I won't have any lights or water until the sun comes up. So we are very careful to keep a weather eye on the power and shut off lights as soon as we don't need them, and since the well is the single largest draw, we are also careful wth water. Luckily we have 2 alternate sources, neither perfect but both helpful: a mini-hydro generator that produces about 650 watts at 48 volts and a 20kW backup diesel generator. The mini-hydro is great until either there's no rain for a few days or the jets plug up (which necessitates me slogging down to the generator pit to clear it out, no fun in the rain for sure). The diesel generator is more than capable of charging the batteries, as long as the electronic controller doesn't fail again, or the oil pressure sensor, or unless the starter battery dies. And all of this is dependent on 2 large silver boxes in the power shed: the master and slave inverters, which turn battery power into house power. Complex? Yes, indeed. But that's my system.
And it is, indeed, all mine. We are off the grid in central Oregon, more than a mile from the nearest power pole, and on the far side of a set of railroad tracks and a major Bonneville Power Administration transmission line, 660,000 volts of clean, renewable, hydro-electric power, and it might as well be on the moon for all the good it does me. Running power to my house would take over a year for permits and cost at least $100,000. Plus I would have power poles running along side my driveway, which aren't exactly beautiful. But I'm saving up for them anyway. Being completely off the grid is just too damn stressful.
Why? For starters, have you looked at the price of batteries lately? Replacing our batteries (Aquion salt water batteries, non toxic and very long life: 10 or so years) run about $1200 each. I have 20. The panels should be good for 12-15 years and will need replacing at $300 or so each. I have 30. The inverters, charge controllers and central control unit have life spans, and so does the generator and the mini-hydro. The wiring should be good for the life of the house, so that's ok. So I baby the stuff, and check on it to make sure it's running properly or we go dark until I either fix it myself, or call a repair person to come out and fix it. I have maintenance contracts with the generator and solar people, but they are minimum 1 hour away and the contracts don't cover nights, weekends and holidays. I'm responsible for the mini-hydro (no-one fixes that for you.)
So it's time-consuming and expensive: the system cost around $110,000. I could have done it for 2/3 that price by using lead-acid batteries and cheaper controls, but I chose a larger, more robust system so my wife and family don't have to muck about testing batteries and managing power even more than we do now. My cost per kWh, figuring how much I paid for the installation and maintenance, is around double what people in LA pay for power, and about 3 times the very low priced energy around me. On top of that I have to spend time monitoring and managing the system.
Could we add wind? Sure, but it would have to be a very tall tower (we're in the valley of the N Santiam River), and I would have to monitor that too! (Also, they're noisy, especially in the area we're in, which is really quiet.) I'm going to upgrade the mini-hydro to a 1.1kW until next summer, which will give me more bang for my buck. More solar panels? Sure, but the basic problem is still there. Look, how much time did you spend today or yesterday thinking about your power? Maybe the cost, if you just got your bill, or the source if you want more green energy. But I will guarantee you didn't spend 30 seconds thinking about capacity, usage, etc. which is a constant worry for those of us off the grid. Yesterday, my wife went to use the microwave and the house went dark. So, off I go in my slippers (where's the damn flashlight?) and call the solar guy who was available to walk me though a new type of issue. I typed up my notes this morning and added them to the 20 or so pages of "What to do if..." notes that hang in the power shed.
I love it that most of the time I have green energy (except when we have to use the generator) and I'm not drawing on the (steadily overloading) grid. But I don't know a single person who depends on solar and who is just trying to live their life, who wouldn't trade for grid power in an instant, if it were practical. If I get grid power up to the shed, then at least I can sell some power back to BPA.
52.6 volts, 98% charge. We’re doing fine for now. I’m off to make dinner.