The computer analogy may still be still valid. I used to build desktops too. It was always a lot of fun selecting the components and the machines did usually come out cheaper than store bought. I'm not sure about today; when we last needed a new desktop I went to Dell. I wouldn't even think about building a laptop, though, which is what the last two computer purchases were. However, there's still a ols desktop in the corner of the office with an overdriven AMD 900 Mhz CPU that serves as a backup media storage unit.

Anyhow on to the PV system question. If one measures the system size by the panels, our system is 624 watts; three 208 watt panels. We have a charge controller that is higher quality and more versatile than what is offered most any pre-packaged kit. Ditto the inverter. My batteries are only golf cart GC2's. From Sam's Club they are dirt cheap compared to any other battery. Picking them up locally I saved a lot on freight costs. So far they are working well, and my past RV experience with them leads me to believe they will be cost effective.

I did spend a lot more money on our system than that one you referenced. Looking at it, I see we have more panel watts and more battery capacity. We also have a lot more inverter. And I have a lot more cable from panel to charge controller.    

Tell you what... you should now have my prototype almost-ready-for-prime-time    PV system sizer tool. Run some numbers through the probable power load sections and send me the file, and let's go from there and have a look at alternative equipment choices.

What are the specs on those batteries that are used in the cell communications trade?  Those could be great to have when priced right.

Nice sheet -- one thing is for sure, I've got a LOT of thinking to do...just running lights for 10 hours a day can change a plan from 6 panels to so many you might as well run and hide!  Sheesh!

"What are the specs on those batteries that are used in the cell communications trade?"

Yes this could be very interesting.

These aren't the exact models we're using but pretty much the same sort of thing.  They are used in sites which must provide a minimum run time for the MW gear (transport nodes, routers etc) of 8+ hours.

What this means is that it should take at least 8 hours to go from -56vdc to -46.5vdc (where most systems die)....though sometimes the equipment will run around -46vdc they are usually dropping like flies then.

I can log into my controllers (in 5 states) right here  

http://www.sbsbattery.com/category_desc.php?cPath=3

We get ours from "Telecom Battery Solutions" more or less -- actually from Magnatek.

But I don't know that they are any better...I would just expect them to be since we're carrying E911 traffic which is well, kinda critical

Wish I had that reliable grid power, eh.  [ouch]

Hundreds out of power since last week - power not expected back for days to come.  I'm so glad the state forced me to hook up to that reliable grid...  OK so they told me I had to and I didn't...

http://abclocal.go.com/kfsn/video?id=7238715

http://abclocal.go.com/kfsn/story?section=news/local&id=7240825

Quote from: glenn kangiser on January 26, 2010, 11:39:06 PM
Wish I had that reliable grid power, eh.  [ouch]

Hundreds out of power since last week - power not expected back for days to come.  I'm so glad the state forced me to hook up to that reliable grid...  OK so they told me I had to and I didn't...

http://abclocal.go.com/kfsn/video?id=7238715

http://abclocal.go.com/kfsn/story?section=news/local&id=7240825

Too bad we all weren't rich enough to fight them in court over these kinds of things.

I have an DC electrical question.

We have a Sundanzer DC electric fridge and we're planning on moving it a little farther away from our power supply. The manual says we should use 12 gauge cable for the distance we'll be at and the fridge comes with a fairly short 14 gauge cable. Should I just get 12 gauge to run from the DC box to the 14 gauge fridge cable, or should I replace the 14 gauge with 12 gauge for the entire distance? To be perfectly clear, do I remove the 14 gauge from the fridge and wire in the 12 gauge directly to the fridge?

Thanks,
Dave

http://sunelec.com/index.php?main_page=product_info&cPath=5&products_id=255
Found these and was wondering if they sounded like decent panels for the money?

I want to put together a system for as little as possible but that will be reliable (within reason)...basically I can't afford $10k in solar power and budgeted $2k but could go a little more.

I need 2 of these 18Vmp panels, 4 Trojan L16RE-B 6v batteries, not sure what kind of inverter but my corrected watt hours per week is 6347 as calculated right now.  Also need a charge controller for the panels.

Since those panels list at $348 that's $696 in panels
Those batteries run about $330 -- so that's $1320 (ouch -- I think I might take Don's approach -- heck, 12vdc deep cycle RV/Marine batters aren't that expensive.  In fact I could get Optimas and save $400 at least and they've got to be decent...maybe I'm thinking wrong?)

http://store.solar-electric.com/xaxwmp60amps.html
I'm still learning (have a long way to go) but this appears to be what I would need for a controller?  I know I could go cheaper but I thought I read the MPPT's were the way to go???

That's $529

http://store.solar-electric.com/xatr15wa12vo.html
$760 for this inverter which has the charger plug in for the generator.

OK so if I went this route then the cost looks like:

$3305 for a 400 watt system with 1500 watt inverter and MPPT controller as well as 4 good batteries.

Hmm...also I have a 3000 watt generator that peaks at 4000 watts and will use that as a back up for the batteries as well as running saws and such (for construction at the cabin).

Thoughts?  Am I choosing the wrong components?  Did I miss something?  Could I reduce costs by going with 6v golf cart batteries?  Is the contoller/inverter combination incorrect?

It's kinda fun mind you, doing this.  I'm using Don's spreadsheet and trying to figure out what kind of power we will need at the cabin since all we've done to date is camp out in the trailer with ONE battery (except one time I had 3 becuase it was very cold) and the main thing that used the battery was heat which we've solved by buying the wood stove   And better insulation.

Anyway, thanks in advance.

WOW!  Just read that the Sams Club GC-2 is $66 at most places and can be found for $44 in some places (Costco maybe?)...in any case that changes my above cost considerably if I went that route.

So, 8 (need 8 due to the lower amp hour rating) x $66 = $528

Overall cost reduced to $2313 for the system I put together

I'm interested and learning here also.  I have not built a system, just read on it, my input does not come from experience. 

I went to google Sams GC-2 for power storage and the first link I found was pretty clear that the lifespan of these is in the ballpark of a year.  While saving money (up front) is great, it might not be soo great to replace them every 12 months. 


http://www.power-talk.net/golf-cart-batteries.html

Our Experience with Golf Cart Batteries

  The third set of batteries to store power for the Ranch was a set of Sams Club GC-2's.  We had two sets of eight hooked in series and then each bank was connected to a buss bar for a 420 AH capacity.  These lasted 12 months.  Thinking that maybe we just got a bad batch, we tried the same thing again.  Twelve months later we were again looking at 16 depleted little batteries. 

  We kept them charged, watered and clean and didn't abuse them with microwaves and such.  The largest DOD they were subjected to was 35% with the average more like 20% - 25%.  Even if you considered each day for a year as a "cycle" that would be only be 365 which is short of the average 500 which we see on a lot of charts.  If we had been hammering them daily with high load devices, this might be understandable but the typical draw we have is in the 3 - 10 ampere range.  One thought was that we should have added another bank of 8 the second time around, for a total of 24 to ease the average load per battery. 

It depends on how off brand you are willing to go and how much risk you are willing to take.  There are many 40 Amp charge controllers on ebay made by smaller wind and solar energy companies that can be had for under $100.  Many have good feed back.  Here is one I have been looking at.
http://stores.ebay.com/Coleman-Air-Parts

Personally for such a small system that doesn't get regular use, I probably wouldn't go so high end, but that is just my personality.  A 1500 watt square sine 12V inverter can be purchase for $150.  You could by 4-5 of them for the price of the Xantrex.

Quote from: Squirl on January 29, 2010, 01:55:07 PM
It depends on how off brand you are willing to go and how much risk you are willing to take.  There are many 40 Amp charge controllers on ebay made by smaller wind and solar energy companies that can be had for under $100.  Many have good feed back.  Here is one I have been looking at.
http://stores.ebay.com/Coleman-Air-Parts

Personally for such a small system that doesn't get regular use, I probably wouldn't go so high end, but that is just my personality.  A 1500 watt square sine 12V inverter can be purchase for $150.  You could by 4-5 of them for the price of the Xantrex.

Do they have the Generator hook up to provide a charge on the batteries when the gen is running?

Good points all -- this is a limited use cabin which I hope to eventually improve to the point that we could spend a lot of time there -- maybe 5 to 10 years later but certainly not as long as I'm working as much as I do!

Quote from: muldoon on January 29, 2010, 01:49:55 PM
I'm interested and learning here also.  I have not built a system, just read on it, my input does not come from experience. 

I went to google Sams GC-2 for power storage and the first link I found was pretty clear that the lifespan of these is in the ballpark of a year.  While saving money (up front) is great, it might not be soo great to replace them every 12 months. 


http://www.power-talk.net/golf-cart-batteries.html

Our Experience with Golf Cart Batteries

  The third set of batteries to store power for the Ranch was a set of Sams Club GC-2's.  We had two sets of eight hooked in series and then each bank was connected to a buss bar for a 420 AH capacity.  These lasted 12 months.  Thinking that maybe we just got a bad batch, we tried the same thing again.  Twelve months later we were again looking at 16 depleted little batteries. 

  We kept them charged, watered and clean and didn't abuse them with microwaves and such.  The largest DOD they were subjected to was 35% with the average more like 20% - 25%.  Even if you considered each day for a year as a "cycle" that would be only be 365 which is short of the average 500 which we see on a lot of charts.  If we had been hammering them daily with high load devices, this might be understandable but the typical draw we have is in the 3 - 10 ampere range.  One thought was that we should have added another bank of 8 the second time around, for a total of 24 to ease the average load per battery. 

Pretty good points -- but Don seems to have done well running his -- so I'm wondering what he thinks? Could be that they over used them more then they admit??

I thought about RV batteries and even Optima's (I have an Optima Yellow Top in my jeep) which run about $200 but figured at that price I might as well get the Trojans -- of course, I might instead try to get some cell site batteries   Since I could probably get them direct from the factory

Quote from: OlJarhead on January 29, 2010, 02:23:56 PM

Do they have the Generator hook up to provide a charge on the batteries when the gen is running?

No.  That is definitely a higher end very user convenient feature of this model. 
If cost is in issue, and you are looking to lower it.
http://www.samsclub.com/shopping/navigate.do?dest=5&item=429487
You could probably find an equivalent 40-50 amp battery charger at most automotive stores.  If you are willing to spend the money up front for a more full time system, Xantrex is always a good brand.  I have had good experiences using their marine units.

Quote from: pagancelt on January 29, 2010, 12:05:26 PM
I have an DC electrical question.

We have a Sundanzer DC electric fridge and we're planning on moving it a little farther away from our power supply. The manual says we should use 12 gauge cable for the distance we'll be at and the fridge comes with a fairly short 14 gauge cable. Should I just get 12 gauge to run from the DC box to the 14 gauge fridge cable, or should I replace the 14 gauge with 12 gauge for the entire distance? To be perfectly clear, do I remove the 14 gauge from the fridge and wire in the 12 gauge directly to the fridge?

Thanks,
Dave

Ideally you'd run the 12 ga the entire distance. But if the 12 is 'fairly short', I'd probably just use the 12 for the extra length needed. If I already had enough 12 gauge laying about, and if changing the cord at the fridge was easy, then I'd likely change out the wire to all 12 gauge.

The 12 gauge will be running roughly 10 to 12 feet, if I don't change out the 14 gauge. If I change it out the total for the 12 gauge will be about 16 feet. I guess I'll have to pull the fridge out and see how difficult it'll be to change out the 14 gauge.

Thanks,
Dave

Quote from: OlJarhead on January 29, 2010, 01:13:15 PM
WOW!  Just read that the Sams Club GC-2 is $66 at most places and can be found for $44 in some places (Costco maybe?)...in any case that changes my above cost considerably if I went that route.

Sam's Club has great pricing on their GC-2's nationwide. My Costco does not sell auto/truck/RV/marine batteries at all.

I believe it is normally impossible to beat the Sam's club GC-2 pricing.

Whether or not they are as good as the trojan, I have no idea.

Once you have the battery capacity required calculated, you can do price comparisons. Most likely the GC-2's will be the least amount of money spent. They likely won't last as long as any L-16, but if you estimate life and factor in $$ spent I believe the GC-2's are a good bet on a small system.

I'll at those other questions you posed later.

Quote from: pagancelt on January 29, 2010, 02:45:28 PM
The 12 gauge will be running roughly 10 to 12 feet, if I don't change out the 14 gauge. If I change it out the total for the 12 gauge will be about 16 feet. I guess I'll have to pull the fridge out and see how difficult it'll be to change out the 14 gauge.

Thanks,
Dave

Dave,  You could also take the quick and dirty route and simply cut off the 14 gauge close to the fridge. Then spilce the 12 gauge to it. As long as you make good connections and tape/insulate well, you'd never tell the difference in power use or loss.

Quote from: muldoon on January 29, 2010, 01:49:55 PM
I'm interested and learning here also.  I have not built a system, just read on it, my input does not come from experience. 

I went to google Sams GC-2 for power storage and the first link I found was pretty clear that the lifespan of these is in the ballpark of a year.  While saving money (up front) is great, it might not be soo great to replace them every 12 months. 

I have a set of 4 of the GC-2's from Sam's Club in the RV. They are now coming up to the end of their 4th year of use. I have no idea if that is typical or if the other guys experience is. One variable that was not mentioned in that article was temperature. ANY wet cell battery will have a shorter life when used in a high temperature environment. Most of my RV batteries lives have been in a cool to cold environment. They spent their first year in the typical desert summertime 90's, but the last 3 in the cool/cold of the mountains.

Quote from: OlJarhead on January 29, 2010, 02:26:10 PM

even Optima's (I have an Optima Yellow Top in my jeep) which run about $200 ....

This is my personal opinion... I love the Optima for a vehicle battery. I have two red tops for the Cherokee. The plan is to replace them one at a time on a 2 year cycle. That way there will always be one battery that is at most two years old.

I believe the yellow tops are a good battery but too expensive for a stationary battery. Optima's big selling point, to me, has been their construction which is pretty much vibration proof. That's a big point in a 4WD that sees off road use.

AGM batteries are used successfully in many off grid applications. They will cost two to three times as much as a flooded wet cell battery, more if you compare to the Sam's GC-2. They don't require maintenance (watering). IF they are charged at too high a rate or overcharged they can be damaged. Overcharging can cause them to out gas and since any lost water can not be replaced that will shorten their life. For that reason AGM's are not run through any equalization charging. 15.5 volts (on a 12 VDC system) is about the absolute max charge voltage.

AGM's also have a much lower self discharge rate than a flooded wet cell battery. Lots of plus points for them. AGM's, by their nature, can only have their state of charge tested with a voltmeter.

Do not confuse a gelled cell battery with AGM. You do not want a gel cell for off grid power systems.

Thanks for the insights, Don.

Quote from: OlJarhead on January 29, 2010, 01:07:20 PM

http://store.solar-electric.com/xaxwmp60amps.html
I'm still learning (have a long way to go) but this appears to be what I would need for a controller?  I know I could go cheaper but I thought I read the MPPT's were the way to go???

That would work but might be more than you need.

Another choice could be the Blue Sky SB3024iL MPPT.    http://store.solar-electric.com/blskysbchco3.html
With it you could wire those panels in series to the charge controller. The controller can charge 12 VDC or 24 Vdc batteries. It has enough capacity for up to 540W (12V) & 800W (24V) panel output.
http://www.blueskyenergyinc.com/uploads/pdf/BSE_Product_Line_Overview.pdf
<$350 or just over $400 with meter.

As for the inverter, that Xantrex appears to be good... the charger section offers loads of power and offers the three stages plus equalization. 10 - 70 amps charger output.     http://lib.store.yahoo.net/lib/wind-sun/TR-inv.pdf

A lot of folks forget about the charger they will need at some point if they buy a cheap inexpensive inverter. Most, if not all, automotive chargers will not have an equalization mode. Something to keep in mind.


Question: Do you already own the small microwave you might want to use off the inverter?  I ask because our small 800 watt (1100 watt draw) microwave will not run on the square wave inverter I own. It hums (louder than on sine wave) but does not produce cook power. I don't know of any way to predict what will happen short of plugging one into a square wave inverter and trying it. In fact I don't know enough people with square wave inverters large enough to know if there are microwaves that will run on square wave. No idea. Maybe someone will know.    I think I recall seeing some people using microwaves on cheap square wave inverters. I'm pretty sure my neighbor in the mountains runs a microwave; I know they have a square wave Xantrex inverter. Again, something to think about.

Thanks Don -- no microwave and I beleive I removed it when the wife told me we didn't need one

I removed the battery charger and some other items and reduced usage based on guestimations made on my last trip.

http://www.infinigi.com/renewable-energy-charge-controllers-c-2_37.html?page=6&sort=2a

this might save you a few bucks on the Xantrex