OFF GRID POWER; various thoughts on...

[MountainDon]

A tracker system would increase power or sure, how much though, I don't know. Glenn built his own tracker and I believe he has the bugs worked out, but I don't know if he has quantified what the power output increase is.

In our case the tracker would have to be "bullet proof" as we are not on site all the time to catch a problem.



Snow/ice. I've been up there during and after snowfalls. Even with the winter angle there was a covering of an inch or so. It did melt off within a few hours of the sun coming out bright though. If we were on site we would be able to sweep the snow o with a long handled broom, or tilt the panels to vertical and cause it to all that way. The slight amount of ice melted off too but took a little longer.

[glenn kangiser]

The tracker was working until the seals went out of the cylinder - it was old. 

I replaced the seals, and I think the only problem is that I have to recharge the west side of the tracker - filled it once but I think the liquid went down to fill the cylinder so I have to fill it again.  Meanwhile it is just aimed south.

[pagan]

Don and Glenn,

Or anybody who wants to put his or her two cents in on the question.

I've been playing around with the generator for charging our battery bank and have learned that if I allow the bank to drain to about 24.2 volts, which should be around 50% discharge, it takes roughly four to five hours to bring the bank back to float. If I recharge at 24.8 to 25 volts, however, it only takes one hour to return to float. Am I better off recharging once a week for about an hour, or every other week for a four to five hour run on the generator?

I understand this is really a personal choice, but I was wondering what you guys think about running the generator more frequently for less time and what this might mean for battery life.

Thanks.

[Dave Sparks]

The deeper you discharge the shorter the battery life! The manufacturer (good ones) will specify the number of discharges that the battery will take. There are dozens of strategies for charging and some are definately better if you are trying to get 10 to 15 years out of a battery.

You should also be checking specific gravity to calibrate your own strategy!  Good Luck!

[MountainDon]

Ditto what Dave said.

I'd be charging them every 2 - 3 days

[Beavers]

Found some pretty good battery info from Rolls Battery.

Might be kind of basic for some folks, but for a guy like me who is just learning it was educational. 

http://www.rollsbattery.com/files/userfiles/Rolls_Solar_Instructions.pdf

[Dave Sparks]

Beavers,

Yes the Rolls info is very handy.  I have most of my 32 customers now on them offgrid.

You must keep in mind that they are in the business of selling batteries! Some of their info is geared for that. There are definate strategies to get 10 to 15 year lifespans and they are, let us say not always going to steer you that way!

Good Luck!

[Squirl]

They could be wrapped on the water heater tank and the foam insulation replaced. I'd have to do some calculations to see if it would be practical or not; cost vs benefit.

Thoughts welcome.

I saw no one responded and I haven't been around much
1 BTU will raise 1 pound of water 1 degree from 60-61.  I usually drop the 60-61 for rough estimates.
So if you have a 20 gallon hot water tank you have 166 lbs of water.
If you have 600 watts power you could get 2000 btu a day in a perfect world with no losses.  
2000 btu/166 lbs of would raise the temperature around 12 degrees by my math.
In a small tank you would see a significant rise.  In a 30 gallon tank you would get 8 degrees a day change.  You would probably lose that overnight.  

On the other hand you could probably build a drain back solar hot water panel for under $216.  At 3400 Btu per square meter per hour you could get 10,400 BTU (3kw) of power in heat even if you only had a 50% absorption rate.

[Dave Sparks]

[/quote]

I saw no one responded and I haven't been around much
1 BTU will raise 1 pound of water 1 degree from 60-61.  I usually drop the 60-61 for rough estimates.
So if you have a 20 gallon hot water tank you have 166 lbs of water.
If you have 600 watts power you could get 2000 btu a day in a perfect world with no losses.  
2000 btu/166 lbs of would raise the temperature around 12 degrees by my math.
In a small tank you would see a significant rise.  In a 30 gallon tank you would get 8 degrees a day change.  You would probably lose that overnight.  

On the other hand you could probably build a drain back solar hot water panel for under $216.  At 3400 Btu per square meter per hour you could get 10,400 BTU (3kw) of power in heat even if you only had a 50% absorption rate.

[/quote]

If they are getting below 40F and your using the batteries you would have to do both or use an exchanger on a generator for bad weather.
I go through this from time to time and try to get people to build the battery house/room very close to the house so it can be conditioned from the house. Lot's easier!

[Beavers]

Dave,

One of these days a set of Rolls batteries would be nice!  I think I'm going to start with a cheap bank to learn and practice with. 

What in the Rolls manual do you think reduces life span?  Their suggestion for what seems like infrequent equalizing (based on other stuff I've read)...or something else?

I'm thinking of mounting my batteries attached to the house in a set up like Mountain Don has.  If the batteries need to be vented, how do you condition the space using the house without sucking all your heating or cooling out through the battery box vents?

Thanks,
Beavers

[Dave Sparks]

Beavers,

I am still laughing from a Crash Test Dummies xmas album about Beaver pelts. I will try to take this seriously. On the Rolls life or avoiding end of life there are many things that over the years they have sort of changed. Some of these things I keep close to my chest for my customers but the one pearl that I will add here is to design so that you "complete" charge most every day. On their site I have seen them say once a week, once every 2 weeks, on and on....  The charge system should be big enough to daily charge and bulk charge at the exact rate or slightly less. If you drag this out too long during the day, you just use more water, expose the terminals to more acid, creat more maintenance.

Yes Don's is similar to the goal and remember that the gas is really only there during bulk near the set-point and during absorption. There are things here that are close to the chest also but one way is to use the AUX on the inverter or the CC's AUX to contoll a very small fan based on voltage set-points. Charge during the middle of the day, use solar, and avoid wind or hydro that has 24 hour gassing, or make these other sources float during the hours that it is really cold. There are other ways and you might pry them out of me over time. You could become #33?, Nah, you can do this!

Merry Chrristmas

[RainDog]

Amorphous-Si PV vs. Crystalline-Si PV modules?

Is this a deal? http://sunelec.com/index.php?main_page=product_info&cPath=5&products_id=543

[Dave Sparks]

Amorphous-Si PV vs. Crystalline-Si PV modules?

Is this a deal? http://sunelec.com/index.php?main_page=product_info&cPath=5&products_id=543

It might be, if they listed snow loading specs and explained more about who provides the warranty. For Offgrid the high voltage controller you would need may be out soon but is not yet! No problem for a grid-tie batteryless though. I do like the high voltage for long distance applications. Sun has great prices but sometimes poor service!

[Beavers]

Thanks Dave!

I've seen those powered battery box vents you mentioned.  With the cold winters I have, I like the idea of keeping the batteries warm. 

[Dave Sparks]

I saw a movie called off the map and it had a line in it like your quote.

"working for someone else is expensive,
you spend so much time there that you never have enough time to do things for yourself"

There is a nice way to do the battery venting passively in a very cold garage and keep them warm!  Do you want to guess how?

[OlJarhead]

Can you compare this system to say, the one you built with separate components?

I'm looking for an idea of the price difference when doing the work yourself versus the convenience of buying a completely put together package versus the component reliability etc in both.

Thanks
http://sunelec.com/index.php?main_page=600_watt_off_grid_system

[Dave Sparks]

Can you compare this system to say, the one you built with separate components?

I'm looking for an idea of the price difference when doing the work yourself versus the convenience of buying a completely put together package versus the component reliability etc in both.

Thanks
http://sunelec.com/index.php?main_page=600_watt_off_grid_system

Sure you can compare! The problem doing this is the intangible questions and their answers.

Like what is it for? How long? Do you expect to add on to it? There are many more questions like how much effort you will put into it? Budget? And the big one, how much energy will you need? If this is for living offgrid keep in mind that there is a very high incidence of failure on these first systems. Half of my customers are someone else's deign that I help the owner design and use properly.

Where did Don go? Snow cabining?

[OlJarhead]

Can you compare this system to say, the one you built with separate components?

I'm looking for an idea of the price difference when doing the work yourself versus the convenience of buying a completely put together package versus the component reliability etc in both.

Thanks
http://sunelec.com/index.php?main_page=600_watt_off_grid_system

Sure you can compare! The problem doing this is the intangible questions and their answers.

Like what is it for? How long? Do you expect to add on to it? There are many more questions like how much effort you will put into it? Budget? And the big one, how much energy will you need? If this is for living offgrid keep in mind that there is a very high incidence of failure on these first systems. Half of my customers are someone else's deign that I help the owner design and use properly.

Where did Don go? Snow cabining?

Good points (and I've heard them all but tend to get over excited and forget to include them)....

Off grid cabin -- not living -- with minimal usage (like Don's).  12vdc pump (that may actually be 24vdc) pumping water out of a 205' deep well into a cistern about 80 feet above it (don't know if that matters at all but I haven't checked amps yet)...maybe some 12v lights and a 12v ceiling fan (or maybe 24vdc) with some 120v outlets for small TV (maybe), DVD player (maybe), toaster, maybe even a small MW oven...who knows really?  After all it's a vacation cabin and not a home.

[MountainDon]

Don (c'est moi) is in Colorado for a few days, to see some real snow (quantities).

We should be back home tomorrow PM sometime, as long as it doesn't snow heavily in or around Raton Pass. 


I'll catch up then.

[RainDog]

Don (c'est moi) is in Colorado for a few days, to see some real snow (quantities).

We should be back home tomorrow PM sometime, as long as it doesn't snow heavily in or around Raton Pass. 


I'll catch up then.

Snowing on Raton

http://video.google.com/videoplay?docid=-6717780685002939476&ei=F2I7S6nVJY6-rALRiOm-Cg&q=snowing+on+raton&hl=en&client=firefox-a#

[MountainDon]

Well, it did not snow on Raton, but it was cloudy and windy and threatening snow north of Santa Fe (south of Raton). Now it's snowing at home.  I'm glad the roads were dry for driving; it is hard dangerous to do 82 mph in snow.


Is that system any good? How does it compare to what you would put together yourself?

You have not answered the question; how much power am I going to use in a day or a week? That has to be answered first, before trying to see how much it's going to cost or if system "xyz" will do the job.

It's tedious, yes. I made my best guesses several times over many months. You must be honest about expected hours of use for each light, microwave, etc. Make two lists, one that you need AC for (microwave type stuff) and the other DC things you might use. Use watts rather than amps and volts as you can change the DC watts into 12 or 24 VDC based systems at any time.  Make the list, round up any odd numbers.

Once you know how much you will use, then the battery bank size can be calculated and from that and the number of sun hours the total PV panel wattage can be determined. Then the charge controller can be picked. The amount of AC power will indicate how large an inverter is needed.

A note on the inverter: you mentioned a small microwave. Be aware that a microwave that is marketed as an 800 watt unit will likely consume 1100 - 1200 watts while operating. That 800 watts (or other advertised number) refers to the cooking power, not the amount of power used.Maybe you knew that, maybe you did not. As it makes a big difference I wanted to be sure on that.

One size does not fit all. You will likely need more PV panels than I would for the same size battery bank, for example because of our different latitudes.

[MountainDon]

There is a nice way to do the battery venting passively in a very cold garage and keep them warm!  Do you want to guess how?

I'm trying to guess, but my imagination is failing me, Dave.   

[Dave Sparks]

One more clue! The very cold 30F garage is attached to the house.

[MountainDon]

Hmmmm....

Is the battery box up against the warm wall?

Insulate the battery box, vent it at a high point and remove any insulation from the house wall where the battery box is located? 

[OlJarhead]

Can you compare this system to say, the one you built with separate components?

I'm looking for an idea of the price difference when doing the work yourself versus the convenience of buying a completely put together package versus the component reliability etc in both.

Thanks
http://sunelec.com/index.php?main_page=600_watt_off_grid_system

OK point has been lost in translation.  The amount of power required or desired is in fact irrelevant to the question asked   So let me try again.

If you built a system yourself (so Don, you have what?  a 900 watt system?) then go out and find a 900 watt (or similar) package (anywhere is fine) and then compare it to yours.

Why?  let me explain:

I used to build PC's.  I went out and found the Motherboard I wanted, the processor, the fan and heatsink, the hard drive, disk drives, CD Drives, graphics cards etc etc etc.  My systems cost less then the big box systems and were better.

To this day my home built PC, while old and outdated, still is a better system then what you can buy in a few ways.  For example, I have more memory slots then most box systems do, I have more PCI slots, more drive bays, more room overall, more fans, bigger power supply, the list goes on and on...and it cost me less (at the time) then something similar from Hewlett Packard.

Now, today, I'm not sure since I no longer go out and buy parts to build a PC -- though I may yet again -- and I've seen a lot of CHEAP box systems that would probably suit me fine today (I probably won't try to stuff in half the things I used to)...

So from this kind of perspective, can you compare one of these 'kit' systems to your home made system?

I'm specially interested in Don't set up becuase I think it's a very similar situation/scenario to mine.  Cabin in remote location for part time use.

I will probably build my own system using what I'm learning here and have a good friend -- who's probably reading this post now -- who's been educating me on the technical side of things (electrical) that I don't know.  I've built Microwave Transport Node sites to back haul Cellular traffic to the MSC (mobile switching center) which includes installing DC power controllers, rectifiers and batteries (series parallel) so I'm not new to the construction aspect of what we're discussing -- might even have a lead on some good batteries to use and will be checking into that since we install them in all of our sites to provide battery backups for the MW gear (-48vdc systems).  Anyway, I digress