Thomas Allen Schmidt's posts

LAST EDITED ON Aug-08-04 AT 06:00 AM (EST)

By any chance are you planing on using an inverter?
If so, one could place the battery bank and inverter(s) in a "power shed" as close as physicaly possible to the array and send ac volts to the load.
If not, there is another alternative. Depending on the size of the load, one could place the battery bank and charge controller by the array and then run an oversized set of wires to the load. If more than one load then of course a branch circuit panel.
But of course this all does incur cost wether one use's a power shed and sends ac volts to the load or a battery encloser with over size wires to load or an mppt charge controller. The battery bank must be protected form tempreture extremes such as freezing.
Outback has a website www.outbackpower.com where one can read the entire MX60's installation and owners manual which has all of the pertinent information one may need to know.

 Consequently the reason
>i asked the question i did,
>granted i should have been more
>specific, is because i have the
>technical knowledge to implement a system
>but wanted a book to look
>into setting up a full system
>w.r.t battery arrays, inverters and net
>metering etc from a technical perspective
>rather than for less technically inclined
>people. Theres nothing wrong with wanting
>to read a book on a
>subject even if you do know
>enough about it.
Go outside and stand facing our Sun and know that it is millions of kilometers away. Know that the planet Earth protects you as best that it can form our Suns radiant energy with its own electromagnetic field as well as several spheres of gaseous matter and ionized water particles, with its lush foliage. Know that with all of that our Sun can still burn your skin in a matter of hours. This is a human condition.
 As for the humanistic, its all about money.
Finding the best deals, or getting the most wattage and longevity for the least amount of expendeture. When I started exploring the idea of "harvesting" electricity from sunlight I did as you are, I wanted knowledge form a book, and I got it, but at a price. The books could tell me how to calculate my energy needs into kilowatt hours and then from there size the array and battery bank and inverter and so on, basic stuff really, Ohm's law mostly except for the orientation of the PV array in respect to our Sun. What these books couldnt tell me though was real world knowledge. For example; even though brand "X" batteries are an excellent battery their terminal posts are fragile at best and subject to break off, the brand "Y" is an excellent inverter but its charge capability is limited even though its advertised charge rates are phenominal, things like how a 16.9 volt PV module would be good for hotter climates but there not and how the peaks of the sine wave of most portable generators flatens out or that its internal combustion counter part is short lived.  
I suppose the point I am really trying to make is that you cant allways believe what you read. Sometimes you just have to write your own book.
Photovoltaics have been utilized since the early 50's but as for using it to power a home off grid, that didnt happen until the 70's. It wasnt untilt the 90's that it started to turn into a billion dollar industry. Grid interteid systems are even younger. Its a realitvly old technology that has a new light shined on it. With this light the market has been saturated with with all kinds of  new technologies promising the consumer  the "best bang for the buck."
I am reminded of a nursery ryhme, I dont know that it apllies to this particular situation, but I am reminded of it all the same. You may have heard it. It starts with an Inch worm measuring Marigolds and after a spell a Butterfly stops in and proceeds to tell the Inch worm, why bother to measure the Marigolds just enjoy how beautiful they are.
I wish you well in your desires for a higher education. Without knowledge from personal experience an education is worth little more than the paper its printed on.
So to close I would say, "spend the money, build a system, and write your own book." Somebody has to.

3,000 kwh a month. If I go by the national average of $0.08 a kwh this would come to $240.00 a month electric bill. If I multiply this by a year that would be $2,880.00 wow! in a life time of paying an electric bill, say 40 years, that would be $115,200.00 I could go even further and multiply that by at least 10 million people nation wide and that would be $1,152,000,000,000.00
But wait it doesnt stop there, it just keeps going generation after generation and going and going and going.......
Eat your heart out Energizer bunny rabbit.

Our you could "just say no" but considering how deeply entrenched electricity has become in our psyc-ee its almost immpossible to walk outside and turn the main breaker off. One might try to raise there arm to do it and its as if some invisible force is pulling the arm back down. AARRGGUUHH, MUST TURN OFF, AARRGGUUHH, MAIN BREAKER, UUGGHUMPH. Even those that have the will power to move mountains and have been able to turn the main breaker off could only leave it off for a short period of time before they walked back outside with both arms raised in front of them, as if they were a zombie under the spell of a vodoo preistest, and turned it back on.

If you feel as if I have made fun of you, then, I apologize. It may make you feel better to know that I lived for over 20 years without any electricity whatsoever, and still went back to living with it. At least I am making my own for my own consumption, and its pollution free. That sort of makes me feel like that guy in the movie -The Matrix- the one that escaped from the Matrix, only I went and built my own and layed down in it. AAAAAAAHHHHH!

All kidding aside, I agree with Brock, consider reducing your kwh's. Nothing is going to reduce an electric bill more than abstainance. Have a professional licensed electrician familar with grid tied PV systems install what you have and just keep installing more PV until you run out of roof space. States as well as power producers vary with the incentives they offer. In the meantime, to learn more, check out http://www.solarelectricpower.org  

Thanks for the info harvester.
If I allready had an AirX 403, and the warranty was up and I wasnt happy with its power production, I believe Id try the conversion, espeacially if my system had a load that could utilize the extra power during those times of high wind. It would have to autonomous though. In other words, for me, the control system would need to be able to match the load to the wind speed. In this way a heavy load during low winds would not stall it and a lite load during high winds would not cause it to self destruct. Something like a bank of water heater elements with relay(s) controlled by a voltage sensor. At low wind speeds one low wattage element, then as wind speed picked up, voltage would raise causing the sensor to drop out the low wattage element and pull in the next higher wattage element. I would be leary of charging a battery bank with it. But thats just me.
Here in my neck of the woods average winds of 10 mph are almost non existant but when it blows it blows with a fury. I live in North Carolina and here hurricanes coming from the Atlantic are subject to show up at anytime between June and November. Not to mention the winter ice storms. I wonder how those blades would hold up to a half inch of ice.
Best of luck to ya!    

General "rules of thumb" for any wind genny are; the bottom of the swept area of the prop is at least 30 foot higher than anything within a 500 foot radius, and the daily wind speed (averaged over a year) is 10 mph.
Wind genny's will make power with less than this, but these "rules of thumb" take cost effectiveness into consideration.
Typically, wind genny's start to make power in the vacinity of 7 mph winds but dont make there rated power until about 28 mph winds. This varies of course from genny to genny.
Go to homepower.com and move your curser over -Education- then click on -wind- and then -maps and data- find your region on the map. The legend is small and hard to read but the scale is easy to understand. White is not good and the darker the blue the better it gets.
Even if you happen to live in one of the dark blue zones it might be a good idea to at least consider photovoltaics to "balance out" an off grid power system.
There is a lot to consider when making the move to off grid living but it is do-able. After all, mankind survived off grid for well over 7,000 years. Its only been about 100 years since the grid was concieved.

Something I happened to think of later is Ground Fault Circuit Interuption or GFCI on the vac side of your inverter. I gathered from your post that you are operating a roadside fruit and or vegtable stand and that the remote PV/battery/inverter system your using is not grounded to Earth. If this is true then there is the possibility that someone could become that path to Earth and get a jolt of electricity if there is not GFCI protection on the vac.
Typically the neutral is bonded to the equipment grounding conductor or EGC (which should go to Earth via ground rod) in one location only. But GFCI protection on certain branch circuits is still Code if not just plain smart.
In the 120 vac (or any polyphase ac) system that your using the neutral has the potential of having 120 vac on it. This current will seek the path of least resistance to Earth.
For example, if you where standing on wet Earth barefoot and touched a metal part of the scales or register, and a neutral wire with a bare spot on it was touching metal (anywhere in the whole system if there is a third equipment grounding wire) you would become that path to Earth and get shocked by 120 vac. GFCI protection limits the duration of the shock to milliseconds by disconecting the circuits power supply. This could happen even in a system that has a ground rod because the current will take the path of least resistance.
So to make it short, use an inverter that has a GFCI receptical built into it. Or a plug in type, but not all types of GFCI devices are compatible with all inverters.
And again seek the advice of a licenced electrician with knowledge of PV and the balance of these systems.  

I took a look at 403 at the Southwest Windpower's web site. They dont go into a whole lot of detail about the 403's. Typical sales brocheur is all I saw there.

This may be a dumb question but, does Southwest Windpower offer a factory made six blade conversion hub and power regulator for its three blade 403's or would this be a "homemade" conversion?
The reason I ask is, where I live the average wind speed and tower cost would not justify the use of a wind genny but if a six blade 403 can produce the same power at lower wind speeds I might be interested.

Hmmm?  Reading what I just wrote, I see what may or may not be the potential for a problem with this idea. As you allready know, the blades are designed to flex which limits the rpm's of the alternator. If there is six blades instead of three then logic would dictate that the total swept surface area has doubled weather the blades are flexed or not as a result of wind speed.

I can see where six blades would be a benefit at lower wind speeds but, if the balance of the engineering designed into the three blade 403's (to protect itself from excessive speed) is predetermined for three blades, I cant help but think that with six blades and excessively high wind speeds it may self destruct.
I would be interested to know what you find out. If you would, keep me informed at this forum?  

I dont quite understand the question. I think what your asking is, can you seperate the charger from the inveter. In this way, you want to use the DR3624's to charge the battery while the gen/set is running but at the same time get your ac power from the inverter instead of it passing through from the gen/set. Is this correct?
Have you asked Trace engineering?
If this is correct, then I would tend to believe that the batteries would still get drawn way down, because if the gen/set cant provide the amount of ac power that the inverter can, how can it replace what the inverter draws from the batteries to make that same amount of ac power?

If you would like to know more about the National Electrical Code or NEC concerning Article 690 Photovoltaics, here is a great site featuring articles written in Homepower magazine by someone many of you may already know.
http://www.sandia.gov/pv/docs/John_Wiles_Code_Corner.htm Have fun!

LAST EDITED ON Jul-13-04 AT 07:05 PM (EST)

LAST EDITED ON Jul-13-04 AT 06:06�PM (EST)

LAST EDITED ON Jul-13-04 AT 05:51�PM (EST)

Fuses and breakers mainly protect the wires in any type of electrical system. The size of the protection depends on the wire size. Although, when conducting low voltage dc electricity sometimes larger wire is used than is nesscesary for the amperage being conducted in order to keep voltage drop to a minimum. Such is the case when a PV array is a long distance from the battery it is charging. Size the fuse to the current being conducted in this case.
To start, look at the short circuit or Isc rating of the PV module. Chances are one module may not be much more then 10 amps Isc. at 12 vdc nominal.
#14 awg copper would carry this current safely with a 15 amp fuse but, if the PV module is more than 20 feet from the battery you might want to use #12 awg copper but keep the 15 amp fuse. Your PV module may be less than 10 amps. If you want to be NEC & UL compliant then you would add 156% to the Isc before sizing wire and fuse's. Thats 125% for NEC X 125% for UL X Isc = ________.
I would place an inline fuse between the PV module and the charge controller as well as the charge controller and the battery.
As for the inverters vdc input, I would take the maximum wattage and divide that by the the lowest voltage before it shuts itself of. This will give you the largest wire size it needs and I would size the fuse according to the size of the wire. For example, if the inverters continuos rated output is 600 watts and it shuts itself off at 10.5 vdc this would come to 57 amps. #6 awg copper is rated at 60 amps so a 60 amp fuse would be good. Again sometimes wire size is larger in order to keep voltage drop to a minimum if the inverter is a long distance from the battery. #4 awg copper wouldnt hurt but keep the 60 amp fuse.
As for the vac, having just one or two devices plugged directly into a small inverter I would not fuse its vac output. Chances are it has its own protection built in. If it where a large inverter powering many loads through out a house then I would protect the branch circuits.
As for where to place the protection. Remember that its protecting the wire but the fuses need to be protected as well from physical damage.
I would place the PV source fuse close to the module as long as its out of the weather (both sun and rain) and the charge controller and inverter fuses just outside of the battery compartment if conveinent. Be sure that the fuse's and fuse holders are UL listed with vdc ratings. Most automotive fuse's and fuse holder's are not rated for PV systems because the open circuit voltage of the PV module can be much higher than a alternator.
Fuse's and fuse holder's are not consider as a means of disconect. So if any switches or fused disconects are used they too need to be UL listed with dc voltage ratings equal to or higher than the open circuit voltage of the PV module and have amperage ratings no less than the fuse size.
Be sure these divices are for copper wire and not aluminum only. Personally I would not want any aluminum any where in a low vdc system.
The same goes for breakers and breaker panels. Square D - QO breakers and panels are UL listed with vdc ratings of upto 48 vdc. Thats not to say that one can use them in a 48 vdc nominal PV system because of the PV modules open circuit voltage. Some 24 vdc nominal system would not be compliant.
Every situation is different. So check with a qualified electrician. Have him look at the situatuation personally.

The National Electrical Code (NEC)Article 690 demands that all PV array's mounted to the roof of multi family and single resident dwellings ( basicaly anywhere there are permanent sleeping arrangements) must have ground fault protection. I am not sure why ether, but its the code, (perhaps the NFPA "see's"* a potential for someone burning to death in there bed) and if a system is going to pass an inspection in the USA it should have it.
I have seen in writting, published by Square D, that thier QO breakers have a UL listed DC rating of upto 48 volts, but I have not seen it in writting for any other brand. I am not saying it doesnt exsist, just that I have not seen it in writting published by the manufatures. And I have asked for it.
Getting back to the 48 volt rating though. As for Square D's rating of 48 vdc, thats not for a 48 vdc nominal PV rating which could have an open circuit voltage of 84 volts. Even some 24 volt nominal PV array's could have an open circuit voltage higher than 48 vdc after calculating NEC Article 690 temperature factors.
As Photovoltaics become more mainstream more inspectors are going to strictly inforce these codes. I do not mean to imply that inspectors are not doing there job just that Article 690 has been a rather obscure article until recently and as for those system that have passed inpections I am sure they are safe in as much as; the wire sizing and, equipment rating are met. There was a time when GFP was required by Code and nobody manufactured it but systems got passed anyway.

* "see's" - Looking into an "live" electrical breaker panel one cannot "see" electricity but there is potential there. As it is true with all physical objects know to mankind they do not exist until they react to or have been reacted on by another object. Fire exists everywhere but as humans we cannot see it until there is potential, it has to react with somethng else. If you close your eyes you cannot see the world but you know it exists because you have the potential for your other sense's to react against other objects in the world.

LAST EDITED ON Jul-11-04 AT 06:40 PM (EST)

When I read the phrase Alt-E my first thought is the Alternative Energy Store, so I would assume that you are asking about books that might be in thier bookstore?
If Alt-E is refering to alternative energies in general then you might want to be more specific. The entire universe is full of energy.
But coming back down to good old mother Earth I can speculate that you are refering to alternatives too; coal fired and, nuclear electric power plants as well as petroleum products. Even here on Earth there is an abundant supply of various energies.
Forgive me but, your question is like asking "I need to know about that tree" while pointing at a forest.
Specifics such as; solar, tidal, wind, plasmas, bio mass, bio diesel, and alcohol. Gosh! I could go on and on. Nasa is developing a way to make electricity from fecal matter.
As an engineering student I am sure you already now that energy is never "used up" it merely changes from one state to another. But you want books. Do you know of the Qabbalah? No? Check it out.

LAST EDITED ON Jun-13-04 AT 05:47 PM (EST)

I see where the Unisolar flexible 32 watt PV module has a Isc of 2.40 amps. If one multiplies that by 156% this comes to 3.75 amps. This 3.75 amps is quite possibly the utmost that the module could every produce, and that would be under some extreme circumstances.

The same module though will produce an Imp of 1.94 amps. If one multiplies this by an equivilent number of hours of full rated charge, which of course depends on so many factors, but I will assume 4 hours, then one would have a total of 7.76 amp hours going to the battery.

It would better to know the amp hour rating of the battery you mentioned at the 20 hour rate, but. I will once again assume. If the battery has a 100 amp hour capacity at the 20 hour rate then then the top 20% of that would be of course 20 amp hours. It would be better to know just how many amp hours will be consumed in a 24 hour period. It would be better to know also if this system will be used full time or just on weekends. In short how much time the PV module will be in the Sun compared to how much time the battery will be used.

But all in all I would suggest the
Solar Converters Inc. PT 12/24-10
There are so many to chose from that would perform equally as well. The reasons I would suggest this is the MPPT technology as well as its ability to directly charge Ion-Lithium batteries which your PDA might possible have. No need to use the inverter just to charge it if this is the case. Alos with a 10 amp maximum ability it will allow you to ad upto 1 more of the same Unisolar flexible 32 watt PV modules if you like to play it safe, 2 more if really what to hot rod it, 3 more for a total of 4 modules if like to live on the edge:)
But like most everything else in this world, the harder that controller is used the less time it could last.

http://www.bioproducts-bioenergy.gov/default.asp

 2.8 AMPS AT 120 VOLTS allday  
2.8 multiplied by 120 = 336 watts
A 12 hour day multiplied by 336 watts =      4,032 watt hours.
At the electric power utilities rate of $0.08
per kilowatt hour this would cost a total of
$0.35 a day rain or shine. Or $63.88 for 6 months of summer.

To do this with photovoltaic it would require an investment in;
1,000 watt PV array
1 Array mount
400 watt inverter
440 amp hour battery bank a 12 volts nominal
60 amp charge controller (with 17.4 volt modules)
Combiner box
If on roof a GFP breaker
This would be a fully autonomous system and it could even run into the night if the attic were hot enough (rain or shine). But thats just it, if it were raining the attic would be cooler so the fan would not run or at least not as long. Whats more is during the winter months it, more than likely, would not run at all. So what do you do with all that surplus power? You could heat water with 12 volt water heating elements but that would mean investing more.
This is just my conclusions though, as with most anything else in life that one may not be absolutely sure about, seek other opinions.

If you have read the ad for a solar powered attic exhaust fan at Alt-E store then you read were all it says is that the panel and motor are matched to ensure maximum power output throughout daylight hours. Its only $309.00 if you were to divide that by $63.88 that the utilities might charge, you can see where the solar fan would pay for itself about the same time the warranty would last on the fan motor. How long of a warranty does the fan you want to use have? The only sure things in life are death and taxes.

The other alternatives are; ridge vents, turbines, opening up the soffits more, and/or bigger gable vents. I have been meaning to find out if there are any biulding codes that would prohibit a chase that would allow cooler air from a crawl space to flow into the attic of a house but have not done this as of yet. One draw back to this idea is that it may not let air move from the soffits across the under side of the roof which would result in a shorter shingle life.

Or you could always open up a swett lodge and charge admission:) It would be my luck the feds would find out about it and charge their tax and then someone would have a heat stroke and pass away:( Death and taxes.

To me the provebial glass of water is neither half empty or half full, its just a glass of water. Thomas S.

LAST EDITED ON May-30-04 AT 08:38 AM (EST)

Knowing that the Sharp 175W-R5EIU has;
Isc of 5.55
Ipm of 4.95
also that the Outback MX 60 has;
a maximum Isc input of 48
and a maximum Ipm output of 70,
am I correct that the maximum number of Sharp 175W-R5EIU PV modules wired to an Outback MX 60 charge controller is
8 If they are wired parallel for 24 volts,
14 wired series/parallel for 48 volts?
If ether of these two configurations were charging a 12 volt nominal battery bank, would this affect the maximum Ipm output of the MX 60?  

http://www.csgnetwork.com/ohmslaw2.html

http://www-gap.des.st-and.ac.uk/~history/Mathematicians/Ohm.html

LAST EDITED ON May-24-04 AT 07:06 PM (EST)

So what have you decided Mike? Iam really interested. Did you go solar with your shed power or tie it into your house?

How about a web site BOBS?

   
>The power estimated for average wattage per
>day is 4200.  
>if this system will supply the
>necessary wattage?  
>

Hours of equivalent full rated charge.
You will need to know this for your area.
Go to www.homepower.com and look accross the top of their home page you see "Education" scroll down to "Solar" then choose the "The Atlas for The Solar Radiation Data Manual for Flat-plate and Concentrating Collectors" fill out the appropriate answers. All you need to know are the number of hours. Work mostly with the winter months since this is typically when more power is used and less is made from a PV array. If the data shows 2 to 3 hours, go with the lesser number. If 2 then simply divide 4200 by 2 for 2100 then divide by 48 volts nominal for 43.75 amps of PV array. Or you can use wattage. 2100 watts divided by a PV modules rated out put. 2100/100=21. This could work with the MX60 controller. 3 wired in series and then 7 sets of 3 in parrallel or any variation of this. Keep in mind though the maximum short circuit amperage and maximum open circuit voltage of the MX60.
It's all in the math using Ohm's law.

 If you go to Outback's web site and pull up the manual for their MX60 with serial numbers 2,000 and up, then scroll down to page 5, at the top of the page you will read (in terms of NEC compliance) that the maximum short circuit amperage from a PV array is (* not more than) 48 amps. The output amperage can be as high as 70 amps. Another one of the great things about the MX60 is the fact that one can vary input voltage from the output voltage and maintain high efficiencies in the transition. There is no longer the need to wire a PV array for same nominal voltage as the battery.

400 watt MH or HPS lights have a similar device. In these lights is a multi tap ballast or transformer. One can feed the light with any one of 120, 208, 240, 277, and recently 480 vac. effectively reducing the amperage with higher voltages, which means more lights on a single circuit, while maintaining 400 watt lamps. But of course direct current would not work through a alternating current transformer. In a manner of speaking, this is basically what the MX 60 can do. Only in the case of the MX 60 the input voltage is higher than the output voltage, raising the output amperages while maintaining the wattage of the PV array to within certain efficiencies. Ohm's law.
I bet Edison would have loved to of had this technology to rub in Tesla's face.

* - "not more than" - a term of NEC compliance.

I see from the inverter designation that we have a 48 volt nominal system. The L-16's have, I assume, 350 amp hrs. @ the 20 hr. rate. Sixteen such batteries wired for 48 volts would give a total of 700 amp hrs. of capacity. Speaking for myself, I like to size a battery bank so that no more than the top 20% of a fully charge battery is use in a 24 hour period, then size the PV array so that it can replace that 20% the very next day provided of course; its a pretty day, the PV modules are in full sunlight from 8:00am to 4:00pm, and perpendicular to the sun at noon time. But thats just me. So, 20% of 700 = 140 divided by 3 hours of equivalent full rated charge (winter time) brings us to 47 amps of PV array at 48 volts nominal. That 3 hours of equivalent full rated charge may vary for your neck of the woods. The Sharp 185W NT-S5E1U has the higher "working voltage" that I like, but it also has the higher price tag. 18 of these would run $14,778 at Alt-E store, where as 20 - Matrix M-PW1650's would run for $12,690. The thing to look at here is the MX60 charge controller and its capabilities. I could be wrong but it seems like I read that the maximum short circuit amperage from the array to the MX60 is 48. I'll have to check on this and back too you.

In addition to what I wrote in the example above, the 500 amp hour battery can be made up of of one or more batteries with various nominal voltages. Such as two 6 volt batteries wired in series to make 12 volts. If each 6 volt batt. has 220 amp hrs. then six batteries would be needed. Three sets of two in series and then those three sets wired in parallel. This would give a total of 660 amp hrs. at 12 volts nominal. When shopping for batteries always compare them by the amp hrs. at the 20 hour rates. I think its best to go a little higher with the batteriers amp hour storge than lower because so many thing can affect there performance such as; temperature, age, and actual usage just to name a few. If your planing on using photovoltaics to charge the battery then simply do the math. Consider the worst case which would be winter time typically. In Iowa you most likely will see about 3 hours of equivilant full rated charge from a PV array in the shortest days of winter assuming the sun shines all day and the PV array is where it is in full sunlight from 8:00 am. to 4:00pm. and perpendicular to the sun at noon time. So with the example of 100 amp hours from my previous post, divide 100 by 3= 33.3 this means the what ever the nominal voltage you will need at least a PV array with 35 amps of charge. The extra capacity of the battery should hold you through 2 to 3 nights/days of no sunshine if your conservative maybe more. This is where a battery monitor pays for itself by showing you just how much power comes and goes. As for wind I have no personal experience with wind genny's. Where I live a 100 foot tower would be required and since PV does so good here I would rather spend that money on more PV. General rules of thumb for wind genny's is that the bottom of the swept area of the prop be at least 30 foot higher than anything within a 500 foot radius and that daily wind speeds, averaged over the year, be at least 10 miles per hour. The one thing I found most valuble to me in becoming grid independent, is a subscription to HomePower magazine. Also I ordered quite a few catalogs from various dealers (even if I didnt like thier prices) because they do offer a lot of useful information on subjects like; wire sizing, the National Electric Code, and the like.  

LAST EDITED ON May-16-04 AT 05:58 PM (EST)

For a time I lived in a 1956 Chevrolet school bus, abit smaller than your GMC, but built like a tank. Its now utilized as a storm shelter here in North Carolina during the huricane season. They just dont build them like they used too.
The first place to start is with figuring just how much electricity you will need in terms of watt hours. Once you have this convert it to amp hours by dividing it by a nominal battery voltage such as 12, 24, or 48. Once you know the amp hours you will need to figure what number that number is 20% of. This will be the battery storage in amp hours. From there its just finding a way to recharge the battery.
Example - If 100 amp hours is needed in a 24 hour period then: 100 is 20% of 500. So a 500 amp hour battery would be needed at the very least.

For the example I gave above this is what I might suggest for part of the system.
6-BP-3160, PV modules - $3,686.40
2-Surette 6-CS21PS batteries - $1,165.90
1-Outback MX60 charge controller - $513.00
1-Bogart TM2020 monitor - $135.00
For a total of $5500.30
This system would use 24 volt modules too charge a 12 battery with an MX60 controller. This is so you can utilize the more readily available 12 volt lights and electric gizmo's. The battery storage I increased by about 50% and the controller isnt max out. This is so in the future more power can be made and utilized. The monitor is important because it can show just how power is made and used which can help you to understand how to use power better for greater satisfation. But there are some many other configurations that could applied to the example above. If you ask 10 different people you might get as many as 10 different systems. A lot of the supporting electrical stuff; wire, fused disconects, and so forth can be purchased locally. I made an array mount out of; old aluminum storm door rails, a couple of heavy duty door hinges, some old steel bed frame angle, and stainless steel bolts all for about $15.00. It holds 6-Solrex MSX77 PV modules and has lasted through the past 5 huricane seasons here in North Carolina. Thomas Schmidt

>need an
>affordable solar setup to run night
>time lights
Affordable thats kind of a broad term in photovoltaics because of; 1-geographical location, 2-watt hours needed, 3-amount of autonomy, 4-availible funds. 1- location, a photovoltaic module with a high working voltage such as 18 volts will charge a battery bank better in a tropical enviroment better than a 16 volt module. The colder a PV cell is the higher it can drive the battery voltage if the batteries dont get too cold. In northern areas the sun shines fewer hours during the winter days than in the summer. All of these things are figured into sizing a system. 2- watthours, this ones easy if only lights are used. just add up the wattage of each bulb and mutiply by the hours the bukb is expected to be used. But remember if in a northern area short winter days mean less power in and more out which leads us to 3- autonomy, sizing the battery bank so that the power used in one night is 20% or less of the total amp hours availible from a fully charged battery bank, and sizing the array to replace that 20% or more the very next sunny day should give you 2 to 3 days of light even if the sun doesnt shine at all. 4- funds, I'll leave that one to you.
Lets asume that you live in central USA. If the PV array can sit in full, unshaded sunlight from 8:00 am to 4:00 pm in the winter months and is aimed perpendicular to the sun at noon time, this should yeild around 3 hours of equivilent full rated charge. So 2 - 100 watt PV module would yeild 600 watt hours. If your house has 6 - 50 watt incandecent bulbs; 2 of them burn for 1 hour, 3 of them for 3 hours, and 1 for 6 hours this would all add up to 850 watt hours. So you see there is a deficet of 250 watt hours. Either more modules or less lights is needed. But there is the 20% of capacity of the battery to consider as well. Going with the figure of 850 watt hours, 850 is 20% of 4,250, now to turn that into amp hours just divide by a nominal voltage; 12,24,48.
I'll assume 12 volts.
4,250/12=354 amp hours (at the 20 hour rate) total battery bank capacity at 12 volts nominal.
850/12=71 amp hours is needed for lights.
So to replace just this amount in one sunny day divide 71 by 3 which equals 24. In this example you would need a PV array the was rated for at least 24 amps at 12 volts and a battery with at least 354 amp hours (at the 20 hour rate). Whew! This doesnt figure in; charge control, module mounts, disconects and fuses, wire, conduit, battery monitors, battery clamps, battery box, shipping, taxes. It pretty much starts with how much power do you need and from there its in the math utilizing Ohms law, Oh! a thick wallet:)
Thomas Schmidt, North Carolina, USA

What kind of help do you need? Sizing the system? Financial? What?

If I understood you correctly, thats a tuff order to fill. But not impossible. Mankind lived that way for at least 5,000 years. Growing thier own vegetables, raising livestock, making thier own bread, building thier home from indiginous materials so forth and so on. They were lucky in a way, they didnt have as many choices as nuclear age mankind has. If they wanted to survive that was the most likely the only way. But in this nuclear age most of the 6 billion human beings on Earth has become a comoditty like so many soy beans or pork bellies, only the purpose is to generate revenues and when one or more humans want to break away from the collective they find themseleves having to deal with not just how to survive as a self reliant individual or individuals, but also with the world they strived to put behind them, or coexist with. The question comes up, can most of 6 billion people be wrong to be so reliant on big industry and behemoth corporations for thier survival? I cant tell anyone if its better to drop a dependencey on something cold turkey or to gradually wean themseleves off of that dependencey, but I can tell you, if you desire a completely self reliant lifestyle you will have to deal with dependenceies brought on by generations of conditioning. Not that long ago, what? 300 years ago give or take a decade, the native Americans lived this way. They didnt know of any other way. They also lived a tribel or comunal life, but they lived from the Earth. Not a work forty hours, pay taxes, buy groceries pay taxes, make the house and car payment pay taxes, etc. etc. and pay taxes. We are born we pay taxes and we die. The point I am trying to make (rather clumsuly) is that to become completely self reliant is very difficult for the indentured servant as well as the the master. They must first be willing to let each other free. You are willing to set yourself free of those that would have you be dependent on them, but are they willing to do the same for you? Or maybe you plan to coexist, a litlle bit of this, a little bit of that, but none of those. Wouldnt this be living in a duallity? Or maybe just compromise's? I sincerely hope that you can find the way and set an example for those in the future to follow. Thomas Schmidt    

There is really no easy answer to your question without knowing all of the specs. of each PV module along with the specs. on the battery bank and how you use power from them. For example; if you have a 1200 amp hr. bank @ 12v nominal, and in a 24 hr. period you use only 20%, and this happens on a regular basis, then with 120 watts of PV module a charge controller may not be nescessary, especially if the PV modules rated voltage (what I call working volatge) is below 17 volts and you live in a climate that is hot most of the year. I started with 6-MSX 77's; 4.5 amps @ 16.9 volts charging a 1320 amp hr. battery bank. I live in the southeast of USA. At the time we were using approx. 150 amp hrs. in a 24 hr. period. During the summer months I could bypass the charge controller because the battery voltage would never get above 14 volts. 13.8 to be exact. But during winter months I would need the charge controller because without it battery volts could soar to 15. Of course its always a good idea to have a charge controller for safety sake, even though the NEC states an exception when the PV source is only 3% of the battery storge after all NEC factors have been caculated, including ambient tempretures. The NEC book can be purchased at most electrical supply house's for around $35. Its a good thing to have. Article 690 relates to Photovoltaics and the supporting systems.