Off the grid living

[hayden]

You touch on an important point - namely "why do you want alternative energy?" There are lots of reasons, and the approach to providing it will vary depending on what you are trying to accomplish.

You mention backup power. That's one reason, and a system with that objective would be very different from one with other objectives.

Less expensive power is another possible objective.

Having any power at all can be an objective - it was in my case.

Reducing or eliminating the use of non-renewable energy sources can be an objective.

It's important to understand your objectives, because they can lead to very different solutions.

I've also got "backup" power at my primary residence (that's on the grid). It's purpose is just that - back up power. It consists of a UPS for the computers and a portable generator with fixed wiring into the whole house. Capital cost was less than $3000, and operating cost doesn't matter because it almost never gets operated. I can survive with little alteration to our lifestyle for many days if the grid power goes out. If it costs two or three times the grid KWH $$ to operate, so what. Once every 5 years I'll pay the $25 for gas.

My other place was first about getting full time power, and second about the cost of that power. Grid power was prohibitive from a captial expense stand point. A full-time generator was prohibitive from an operating cost and maintenance standpoint. The solar with backup generator was 2/3 the capital cost of the grid power, can be left unattended for months on end, and has extremely low operating cost (lower than grid power since I recovered my capital costs plus some before I ever turned it on). The low consumption of non-renewable energy sources is a great side benefit.

Two different needs, two very different solutions.

 

[benewton]

I agree with what you've written.

The best use of technology is to apply it to your specific needs, in whatever concentration is required, to accomplish that which you've set as your goal.

It's nice to have the basics available, though, and not a little amazing, if you think about it for a bit...
I'm sure glad I didn't have to do the Middle ages gig, but then, that leads to another thread.

As for me, I now need to sit down and design a totalizer for the size battery bank that I have, along with the generator control circuit, some type of "keep the battery warm" failsafe, and an AC vent drive controller, since the DC fans currently in use seem unlikely to vent the batteries under really hard recharging. Too, I don't think the Trace method of measured voltage causing the battery charge to begin is valid, although I guess it works.

Oh well, for a change I get to utilize my career skills to advance my own purposes, which isn't a bad thing either!

 

[hayden]

Regarding your generator control - Is that to provide electric start/stop for the generator so your Trace can control it?

I ended up getting an Onan RV generator. It was very attractive for a few reasons, many of which may be specific to my needs.

First, it has the stop/start control stuff built in so it was just a matter of wiring to allow it to be controlled by the Trace.

It's 110V only and you can pull the full rated 30A out of it at 110V. This was key to powering the Trace as a battery charger. Many generators with split 110/220 wiring can only deliver about half of their rated power through any one of the 110V circuits thereby significantly reducing the effectiveness of the generator. On the other hand, the 110/220 setup is ideal for powering a normal house since that's how they are wired. My place is all 110V so the Onan was a great match for my needs.

It's quiet, runs at 1800 RPM for reduced noise and longer life, and the Onan 2 cyl engine has a long established reputation for trouble free operation.

It's built for installation in an enclosed space so it's designed to take cooling and combustion air from the surrounding space, and exhaust both out the bottom via a nice clean duct design. This made for very easy design-in and installation in a shed. I basically just cut a hole in the floor and bolted the generator over the hole. It sucks air in from teh shed interior (there are wall vents) and the hot air and exhaust blow out the underside of the shed. For any other generator I would have had to design some forced air cooling system for the shed plus a fancy exhaust system.

This generator was my sole source of charging power for the first year, and was used heavily for another year while the house was under construction and much more power was being consumed that the solar panels produced.

It's got almost 900 hrs on it and runs like new. I ran it for the first 100 hours or so on gasoline, then converted over to propane once I got my bulk tank installed. I'm very happy with it.

Also, even though it's only a 4KW generator, it will run my Trace at a 90A charge rate which is about as fast as I can charge by battery bank anyway (it's about 800 AH).

 

[benewton]

The "battery control panel" will be a multifunction unit for a number of reasons.

My batteries are located indoors, and have to be power vented. While I've a DC based system which powers on the fans when the power bus voltage exceeds 28 VDC or so, I note that the charging waveform is NOT DC. Too, I'm not happy with the fan output, and so will go to a 6" vent pipe with an AC fan.
Since I'm running the units as separate 110 VAC inverters, I have to be able to select one of the two, since they run split 220, currently, and you have to consider the death of one unit while the other soldiers on.

Next, I want some backup against freezing, and so intend to put in some type of electrical resistance heating. While we do have "backup" propane heat, it provides hot water heat only to the main floor, not the basement, and the airflow for the woodstove, our primary heat source, leaves a bit to be desired.
At this point I'm considering some type of register or duct... It hasn't really been a problem, but suspenders back up belts really well, and the cost is low enough to make the gain in peace of mind worth the effort.

Finally, I note that the Trace units will automatically control the generator, but they do so on the basis of voltage, not battery capacity. There is not a commercial unit available which will totalize the current battery capacity at the level I need (8*415 AH= 3320 AH), so, if I want to monitor capacity I've got to do it myself.

The plan is to design a circuit which monitors the current into and out of the battery bank, maintaining a total of the available amperage as well as the current "age" of the battery, the latter a function of, as I'm sure you know, of the total number and depth of the discharge cycles.

I plan to recharge the battery when the capacity falls to 80% of that available, which should give me 3000 full charge/discharge cycles before the batteries "wear out". Since the Traces will charge given an external source, there's no need to mess with the packaged electronics, and I need only control the generator ON/OFF.

As for the generator, I'm thinking of a middle sized diesel, say 20KW or so, since I've some other plans later which'll probably require more power than the basic system. I have the shed already, and I guess, while the gas unit is cheaper and would probably be OK, I don't like the idea of storing gas in an enclosed area at all. Besides, I need diesel for the 40D and, if I ever kill off the current F150, the truce.

I should note that I've an overdesigning attitude: I only want to do this once!
Designed correctly, with no shortcuts, it should run 20 years or so, by which time, given my/our ages, it'll be someone else's problem.

 

[hayden]

You've got quite a system there. Next time the power fails we'll all know where to go to keep warm.

Be sure to get a spark-free fan for the vent (but you probably know that).

It's too bad the existing battery meters do give you a few relays that you can program so you don't have to build it all yourself. It also seems it would be an easy thing for trace to build into their product. I agree it would be nice if their charge initiation was based on AH drawdown rather than voltage.

 

[Anonymous Poster]

If you are interested in self-sufficiency, there is no better place than www.countrysidemag.com, other than subscribing to the mag.

 

[benewton]

I've given some thought to designing the circuit for commercial applications, since it seems like such a nice combination of funtions, and I probably do have the contacts to have it produced and marketed, maybe...

The problem is that it's very difficult to design something that would fit all applications, especially when you consider that your average user isn't anything close to an engineer. Then, too, there's the liability problem, and, considering the market for the product, there's probably insufficient buyers to make the effort worth the risk with any concentration on a specific product to be supported, say, for instance, Trace inverter power panels.

Ah well, the consulting market seems a bit short this year, and one's mind does tend to wander into places where it has no business going....

I'll check the magazine site ASAP...

 

[JoeR]

My comments are not necessarily on topic, but I recently notice that BP Gas Stations here in Florida have a ton of solar panels on top of their gas stations. From what I have heard, all their lighting is powered from batteries which are charged by the panels.

All this talk of solar panels has made me aware of alternative power, and I suddenly noticed BP uses alternative power...




Joe

 

[hayden]

BP is actually a very large manufacturer of solar panels, so they are demonstrating/advertising their goods. In the past year or so they bought Solarex which was a good panel manufacturer out of Maryland. Siemens and Kyocera are the other two big guys. I don't know what their relative market shares are.