SOLAR

[geron]

Costs currently:

8 batteries @ 159= $1272.00
Inverter @ 869.00
Refer @ 1099 (if required)
Sub total: $3240.00

[thywar]

I'm guessing you're going with your existing refrigerator or you could add the $1099 for the Amana that TJ is using in the example...

[geron]

Aug 19, 2012 4:55:38 GMT -7 thywar said:

I'm guessing you're going with your existing refrigerator or you could add the $1099 for the Amana that TJ is using in the example...

Yep, Mine will do for now.

[tjwilhelm]

A few comments before going further...

The important thing in this string of posts is the sizing procedure; NOT the specific hardware being used.

This is a sizing EXAMPLE, and not an intentional endorsement of specific brands or components. For the sample items in this sizing example, I'm using mid-range components -- mid-range in both cost and quality. Note that the Amana fridge has moderate ratings by consumers. I just grabbed it as a sample of a lower-cost, higher-efficiency unit than some of the so-called "solar refrigerators."

Also, I like the Xantrex/Schneider TR inverter; but, it is a mid-range inverter/charger; not just a plain vanilla inverter. You can put a 120vac input on it and use it to charge your batteries when the sun isn't shining. Therefore, it will cost more than a simple, Chinese-made inverter.

Like with most anything, there is a wide range of component prices and corresponding quality. You could do this for less money than the cost of the example items here. My only caution is to be sure to shop for quality as well as price. If this is going to be a stand-alone, survival system, quality will be highly important, and probably worth paying more for.

[thywar]

I understand that and it's helpful to know the ranges. I agree I wouldn't want the cheapest but practically speaking I can't afford the most expensive.

[tjwilhelm]

Step Four: Size the Solar-PV Array.

Sub-Step Four "A" -- Solar Resource?

The solar-PV array is sized based on the size of the battery pack, the size of the load, and the available solar resource.

Of course, the solar resource varies from place to place and from season to season. This example will focus on a midwest location.

For a stand-alone solar-PV system, you typically need to use your "worst-case" solar resource data. This typically occurs in December, around the time of the winter solstice. However, because this is a system specifically aimed at providing refrigeration, we can downsize the system and use the spring/fall solar resource, assuming you are willing to move your food outside into the naturally cold winter environment, in the event you run out of battery power to keep the fridge running.

Thanks to early solar scientists and engineers from the USDOE, we have a convenient concept called "Peak Sun Hours," and we have tons of data that can give us a very fair estimate of our solar resource at any point on the planet. Sub-step "A" involves finding the appropriate "Peak Sun Hours" for your location. For a summer camping cabin, you'd be looking for the available summer average of "Peak Sun Hours." For a year-round or winter-only hunting lodge, you'd be looking for the available winter average of "Peak Sun Hours." For our survival refrigerator, I think we can use the annual average of "Peak Sun Hours." This will give us all the sun we need until it gets cold enough outside to help with our refrigeration chore.

Here's a link to one of MANY sun-hour maps available on the web. For our midwest example, I'll use Dink's Missouri. Notice that on one side of Missouri the annual average is 3.3 peak sun hours per day. On the other side, the annual average is 2.7 peak sun hours per day. For Dink's farmstead, we would use an annual average of 3.0 peak sun hours per day.

Sub-Step Four "B" -- How much PV is needed?

First, go back and capture our daily load:

The load = 1,230 WHrs/day = 52 AHrs/day at 24VDC.

Divide the load by the available peak sun hours:

1,230 WHrs/day divided by 3.0 Hrs/day = 410 W

52 AHrs/day divided by 3.0 Hrs/day = 17.33 A at 24VDC

I would take these numbers and round up a bit, to account for system inefficiencies. This means we would need a solar-PV array that is rated at between 420 W and 450 W, and will give us about 17.5 A to 18.0 A, at 24VDC.

For those tracking costs as we go, it's possible to buy PV modules these days for about $1.50 to $2.00/Watt. Thus, for the modules, we're looking at a cost of about $650.00 to $900.00.

Here an EXAMPLE PV module:

www.saferwholesale.com/230-Watt-Solar-Panel-24-Volt-PV-Module-p/aim-pv230poly.htm

We would need two of these modules, wired in parallel, to feed our system.

Step Five: Select Balance of System Components.

(Coming soon...)

[kutkota]

Thank you for sharing your kniwledge! Is wind power something to look at? The few pieces of info I have found online would eliminate them as I would like it to be semi portable. I will probably be moving every four years or so and the requirments for a wind turbine seems to be out of the picture. Am I missing something?

[tjwilhelm]

Aug 19, 2012 10:16:25 GMT -7 kutkota said:

Thank you for sharing your kniwledge! Is wind power something to look at? The few pieces of info I have found online would eliminate them as I would like it to be semi portable. I will probably be moving every four years or so and the requirments for a wind turbine seems to be out of the picture. Am I missing something?

"Portable" is a relative term. If you have a truck, a 12' trailer, a few people to help you, and a few day's work at each end of your move, then there are a few small (1 KW) turbine/tower kits that could be "portable."

FORGET roof-mounted units, vertical axis machines, and other bogus gimmicks. Here's an important rule of thumb...the bottom of the swept area of the turbine (the lowest point reached by the blade) must be at least 30 feet higher than anything within 300 feet. Proper tower height is critical!

Here's a video of some of my students installing a Bergey XL1, 1 KW wind generator. The base of the tower is a flat steel plate that sits on the ground. The guy-wire anchors are auger-in foundation points. NOTE: for this to be "easy," you need proper soil conditions...NO BURIED CONCRETE FOUNDATIONS! Also, you would want to stockpile extra auger/anchors...these guys would be tough to extract:

[olebama]

TJ,
Is there a book you would recommend to learn about solar setups? I am avidly reading your posts. Thanks much for the info.

[tjwilhelm]

Aug 19, 2012 19:15:38 GMT -7 olebama said:

TJ,
Is there a book you would recommend to learn about solar setups? I am avidly reading your posts. Thanks much for the info.

This is the textbook I use for my solar-PV course. It's a bit technical and kind of pricey; but, currently, it's considered the best text on the subject:

www.amazon.com/Photovoltaic-Systems-James-P-Dunlop/dp/0826913083/ref=sr_1_sc_1?ie=UTF8&qid=1345433013&sr=8-1-spell&keywords=phptovoltaic+systems

There are MANY books out there, less technical and less expensive. Some are pretty good and some are definitely not. Just go to Amazon and do a search for "photovoltaic."

If you want some high quality seminar-type training, there are four excellent non-profit groups that provide weekend workshops from roookie level to advanced training:

• The Florida Solar Energy Center (Florida): www.fsec.ucf.edu/en/
  
• Solar Energy International (Colorado): www.solarenergy.org/
  
• The Evergreen Institute (Missouri): www.evergreeninstitute.org/index.cfm?action=DisplayMain
  
• The Midwest Renewable Energy Association (Wisconsin): www.midwestrenew.org/home
  

All four groups sell good books and they also offer some online training.

The Midwest Renewable Energy Association, in particular, has some pretty out-there instructors : www.midwestrenew.org/node/3103

[woodyz]

Your thoughts on this "POWER4HOME SYSTEM 2.0"

www.power4home.com/

My son is looking at it and asked me to look at it, but I am not sure I know enough to give a good answer.

I am always wary of any "I've got your fix" deals, but maybe it offers something.

Your our go to guy on this subject.

[olebama]

The Midwest Renewable Energy Association, in particular, has some pretty out-there instructors : www.midwestrenew.org/node/3103

Thanks for the info, TJ. I don't know about the Midwest Renewable Energy Association, I think their instructors are wayyyyy out of my league.

[woodyz]

Did I miss step five? Or is it still being cooked? Not trying to rush anything I just tend to get lost a lot lately.

[Deleted]

Thank you, TJ!!!

You are simply amazing!!

[tjwilhelm]

I'M SO-O-O SORRY!!!

I'm back teaching at the college again, I'm drowning in work created by a new grant I received from the National Science Foundation, I'm doing a boat load of heavy physical therapy, and I've been on an intense search for a surgeon who will be willing and able to rebuild my broken body (SUCCESS on this last one, as of two days ago!!!). On top of all that, I foolishly enrolled as a student in a course on "Sustainability" at the University of Illinois...AGH-H-H!!! I just haven't been able to make time to get back to this...YET.

I'm going to do my best to get back to this thread with a detailed post in the next week to 10 days.

Apologies!