Thomas Allen Schmidt's posts

Its almost sounds lie you have made up your mind allready, your just not sure of the equipment needed.
One senario might be to have a grid tied/battery back up inverter at 220v 50Hz. There are a several on the market and Alt-E sells them.
Have one PV array at the nominal dc voltage for that inverter.
Then have a second inverter to perform the duty of 120v 60Hz. from that same battery bank.
As for the number of watt hours, of course you would want to size the PV array and battery bank for nothing less than the needs of the 120v 60Hz. system.
The 220v 50Hz. grid tied inverter will have a battery charger as well so the 120v 60Hz. side of the system well have its back up for cloudy days and all.

That is quite a dilemma, because no matter which way you go its going to cost you money. Either by purcahsing the equipment to run the 60 hz. appliances or by selling them dirt cheap to get rid of them all.
If you keep the 120v 60Hz. appliances and purchase the equipment to run them from 220v 50Hz. there will need to be either dedicated circuits in the home or several portable devices. On the other hand, by selling them all for whatever you can get or donating them all to a charitable cause here in the states you will not have to worry with any of that conversion stuff.
Either way there has to be some sacrifice.
Go with the charitable causes.

Could be that both the gen set and the inverter have there nuetrals bonded to ground, confusing the micro processor into a ground fault situation. If this is the case it would be easier to isolate the bond at the gen set because if I am not mistaken on the DR1512 it is bonded internally. Consult both Trace and Onan to be sure. There could be a list of other problems here.

Don't know that much about the Onan microquite 3600 watt generator but it sounds like it has some sort of fuel miser gizmo on it, but instead going to idel when there ain't no load, it shuts down. Damn nussance I'd say, get rid of it, save even more fuel.

 We need
>help in placement of the generator
>to minimize the noise.
Which location
>will reduce the noise from the
>generator the best.
This property
>is so quite now that we
>can hear the wind on the
>wings of the birds as they
>turn and we would like to
>keep it as quite as possible.
>Thanks, Avocado

At the risk of sounding like a jerk,
I would have to say the best place would be the warehouse of the plant where it was manufactured.
Seriously though, did you know that the utilization of electricity by the masses has been going on for only about 100 years. I know elderly people that have told stories of their childhood and living without electricity. Mankind had  survived on the planet Earth for well over 7,000 years without the electricity we all take for granted today.
In a lot of ways electricity has the affects of an addictive drug, but thats all I will say about that, since I dont know you personally.
What has the utilization of electricity actually done for mankind? Acid rain? Dead lakes? Respratory diseases? An ever increasing rate of increase of human population?
From the beginning upto the year 1940, world human population is estimated to have been 2 billion. From the years 1940 to 2004, world human population is estimated at 6 billion. By the year 1926, only 60% of the people in the United States of America had electricity in their homes. Thats just a little more than half.
Mankind does not need the utilitazation of electricity to survive on the planet Earth.
We never have.
It may come to the point where we have to abandon the utilization of electricity in order to survive though. Only time well tell.
Imagine that, a world with no utilitized electricity, oh wait a moment, we dont have to imagine, we just have to look at our history and what we have lost since the likes of Thomas Edison and Nikola Tesla and George Westinghouse walked this Earth.

 I saw where you wrote in the header "gel vs sealed" but personally, I prefer the deep cycle flooded cell lead acid type. Sealed gel cells have there use's but a deep cycle flooded cell lead acid battery just feels right some how in an off grid home with photovoltaics as a the charge source. Sure theres a chore with replenishing the water and all but I dont mind that. It actually helps me keep track of how my batteries are doing.
I've always wanted to try some of those submarine batteries. 7,000 amp/hrs @ 2 volts nominal, but at $3,000.00 each its hard to justify the cost, I mean, even though they say these things will last 35 years in the harsh usage enviroment on board a sub and that they could last a life time in an RE home, a 12 volt battery would cost $18,000.00
Not that I need that much amp/hrs but thats the catch. One cycle of any rechargable battery is from 100% fully charged down to 20%, anything less than that isnt even usable. So lets say I size my battery bank to stay within the top 20% of fully charged over night and then size the PV array to replace that in one sunny day, well then I get more cycles this way. Of course there will be days when then sun doesnt shine, even several days in a row, so I would take that into consideration as well. Its all in the math. When you find the batteries you like, consider doubling the amp/hr capacity for performance and longevity.
I just wish there was a shorter name than,
deep cycle flooded cell lead acid.  

>i will
>buy a second inverter to form
>my 220 as you suggested as
>a slave.

Hold your horse's. I dont know enough about that particular inverter to suggest to you, buying a second one and wiring it into your breaker panel for 120/240 vac. The information available for the Aims 5,000 watt inverter is little more than a color brochure, even at the company who built it, web site. They make no mention of there inverter being able to produce 120/240 vac with a second inverter. They make no mention of it being able to produce 120/240 vac by itself.
There has to be a preciesly maintained offset of the two 120 vac legs, and this changes with varying loads, so there has to be an interface to maintain the offset between the master inverter and the slave inverter. The only one who could provide this would be that particular inverter manufacture, in this case Aims, and nothing on there web site even suggested that they make such a device.
I suggest that you do some more research first.
Then hire a professional, licensed electrical contractor to perform any electrical work done in or on your home. This would include getting the nesscessary permits and inspections.  

I found very little technical informatin about it. I was hopeing for more. All of the info I found said only 120 vac. There was something about getting full power from one outlet, one must use larger vdc cables. To me that sounds crazy. If I were to size a cable or cables for any inverter, I would divide the continuous wattage by the lowest vdc input voltage. In this case that would 500 amps which I would use nothing less than parallel 4/0 cu. wire. What did they sell with it? Parallel 2/0? Not to mention the vac output of over 40 amps from one outlet. But this doesnt help you any does it?
If I had one of these inverters, just out of curiosity I would use a multimeter and with one probe in the hot side of one outlet I would check for voltage to the same side of each of the other three outlets. Its probably not there though because this would be something they most likely would advertise.
I read where it has phase correction. I am drawing a blank on that one. If there is no other inverter to be the slave then what is there to be corrected? Its ok, you dont have to answer that.
The Aims web site is as informative as any of its resellers ads. Its probably a good inverter, but if you plan on loading up to full rated wattage, keep an eye on those cables. If you havent already it would be best to give yourself a quick disconect on that vdc inverter input circuit with fuses to protect the wire. 500 amps is a lot, even at 12 vdc. One could weld 1/4 steel plate together with that. A lot of 4x4 offroaders have used less amperage at 24 vdc to make emergency repairs on broken axles and such.

>i would like to know if you
>can run an inverter to two
>legs of your elect.panel to form
>220.
Where you wrote "an inverter" I take that to be 1-inverter, if correct then the answer is no. The electricity brought into your home from the electric utilities is called 120/240 vac single phase @ 60 Hz. This simply means that there is 2 "legs" of 120 vac @ 60 Hz out of phase with each other. In order to make 120/240 vac single phase @ 60 Hz. with inverters there must be two inverters and one must be the master the other a slave. Unless of course they are made together as one unit, but the princple is the same, there must be two "legs" of 120 vac out of phase. Oh! and there must not be any multi-wire branch circuits (two circuits sharing the same neutral) leaving your breaker panel.

also my aims converter has 4
>1500w outlets, can you double up
>on the outlets to form 3k
>watts. the manuel mentions nothing to
>this effect.

More than likley not. If you could see the back side of the outlets you might see that they are all wired together on one circuit, even though they might have different mini breakers. I am going to research Aimes inverters learn more about them.

Look at it all in terms of wattage.
The higher the wattage demand the higher one would want the voltage.
This done to keep cost down as well as safety issue's.
Example: if an inverter is rated 5,000 watts at 12 volts that would be 417 amps. That same inverter at 48 volts would be 105 amps.
Even though the cost of the inverter might be the same, compare the cost of the; wire, conduit, fused disconnects, and fuse's.
As for safety, most inverters have an automatic low battery voltage disconnect. Typically around 10.9 volts for 12 volts nominal, times 4 for 48 volts nominal. Figure wire size for an inverter at these lower voltages and you will see that the amperage goes up.
Research Ohm's Law as well as the National Electrical Code.

As for pricing, it could be that the differences you see are for different inverter technologies. Squarewave, modified squarewave/modified sinewave (same thing), and sinewave, which is actually a whole lot of little steps. The only way to get a true sinusoidal waveform is from a rotating or spinning force. Everything else is just a close copy. We always see a representation of a waveform in one dimesion, but in reality its three dimensional look is like that of a slinky streched out.
Hope this helps.

LAST EDITED ON Oct-09-04 AT 06:18 AM (EST)

It would appear that there is some conflict amoung the three devices. The question is, whats the conflict? I reviewed what nomenclature I could access on the three devices. For some reason I could not access any documents from Xantrex on the XP300 plus. So, based on that, this is my acessment.
If the X Power 300 plus is designed for plugging into a cigarette lighter and there is no PV source input "plug", then its built in battery charge regulation is designed for automotive charging systems which are lower in nominal voltage (14.6 or lower) than PV nominal charging voltages (16.5 or higher) for 12 volt nominal batteries. If I understood you right, direct PV power applied to the XP300p through its automotive charge input source, causes excessive gasing which means of course to high of battery voltage. Then with the Solsum 8.8 in line the battery doesnt get enough of a charge to replace the amphrs used within say 4 hours of equivalent full rated charge.
The Solsum 8.8 would appear to be a little too protective. It sounds as though it is getting "confused" and diverting the differences in voltage to its heat sink. Does it get hot sometimes?
If at all possible, I think I would try a simple on/off charge controller with adjustable set points and set them to simulate automotive charge voltages, if the only vdc input on the XP300p is indeed a cigarette lighter plug and there is not a PV source input. Nothing that I could find on the XP300p said there is a PV source input.
A trick you might try to see if I am correct would be to shade part of the US 21. Manually maintain its voltage around 14.6 (without the Solsum 8. using a piece of cardboard or something.

Wow! thats great. Congraulations, its not everyday that this happens. Theres only one thing that might even come close to watching the meter spin backwards and thats occasionally getting to watch a meter reader go round and round my house scratching his head looking for the electric meter and there isn't one.
Lets see thats 12 at 165 watts for about 4 hours a day averaged over the year. That would come too about 8 kilowatthours a day. More in the summer, less in the winter of course. I would say around 60% of the year for a grand total of 1,700 kilowatthours a year at $0.08 a kilowatthour (national average) thats $136.00 a year! Thats like a free month of electricity every year.
Hey, I wonder if the power company here would pay me that much a year as long as I dont every hook up to there coal fired generators or nuclear power plant.
There's a web site where you can see just how much pollution that PV array will offset.
http://www.cleanerandgreener.org/pollution-from-electricity.htm

http://kingsolar.com/catalog/dept/hotwater/solar.htm
Maybe something here will help.

Cost, thats the whole thing in a nut shell.
Typically speaking, an off grid renewable energy (RE) system utilizing; photovoltaics (PV), deep cycle batteries, and an inverter are only cost effective in situations where the cost of running a line from the power company is cost prohibative. Other than that the cost is about the same. The differance is in paying for it a little each month for the rest of your life or paying for it all at once. There is also battery replacement to consider.
So, if your bill was 170 bucks a month, that would be 2,040 clams a year.
Now, if you where to pay this bill for forty years thats 81,600 scamolies.
Wow! if I could of had that kind of dough all at once when I built my system knowing what I know now.
With a stack a jack that tall I would start with;
2 - 5548's
Around 2,000 amp hours of Rolls or HUP Solar One's or the equivilent @ 48 vdc and its eventual replacement.
Then figure up whats left over and spend that on the PV array and its infrastructure; mounts, wire, conduit, disconects, MX 60 charge controllers, and so forth and so on. Who knows maybe even a wind genny.
Or one alternative might be to learn to live without electricity and stick that wad in a sock.
But then again, you cant take it with you. There is a reason wy hearse's dont have lugauge racks and bumper hitches.

Knowledge is power, and it is a good thing in the right hands. http://energy.sourceguides.com/index.shtml
It has always amazed me that mankind survived without electricity (as we know it today) for well over 7,000 years, but over the past 100 years it has gotten to the point were the masses cannot live without it. I include myself in this. Still, if electricity is to be used its best done with as little impact on the enviroment as possible. After all, we only have one planet to live on and to live from. Thats one of the reasons I choose to live off grid.  

 
>I have always been into self sustaining
>living.
>
>>Any suggestions are on any of the
>above would be great.
>Thanks, Jaosn

Try to find as many back issue's of The Mother Earth News as you can, you might find some at a library- its hard to say, and read, read, read.
Oh! there is a Mother Earth News web site as well, although nothing like the earlier printed issue's from the 70's and 80's. It's these early issue's that you want.

Have you tried
http://www.outbackpower.com/manuals.htm
They also have a forum with answers from there tech. reps..

Try
www.backwoodssolar.com
Depending on the amperage it may be necessary to use the vdc timer to pull in and drop out the vdc coil of a high amperage vdc contactor such as those used on electric vehicles.
www.evparts.com

Wow, I knew that some inverters have charge controll for there own built in transformer/rectifier charging system from an outside source (typically 120 vac), but I did not know there is an inverter on the market that has a built in PV source charge controller. Would you tell me the brand name? I'd like to learn more about them. Thanks.  

I am no pole rigger but I can see several aspects here that need to be considered.
Swept area and tower top wieght of the wind genny.
The swept area of the propellor is consider as one solid flat surface, like a sign.

Is there a chance of ice from freezing rain?
Ice can add a lot of wieght to the tower top wieght of the genny.

Wall thickness of the 4" steel pipe.
Is the pole material you want to use part of a package that would otherwise require guy wires?
If so then there would need to be support on the pole at the same points that guy wires would go.
In otherwords there would be a bracket securing the pole to the tower just before the pole leaves the tower or somewhere there abouts, and then possibly guy wires closer to the top.

Another way of looking at it.
I ve done things for myself in the past in such a way as to lessen the expenses of the overall job and where some of them were a benefit there have others that have bit me on my hind parts.

 
>Inverters that are designed for solar applications
>generally have a blocking diode or
>equivalent circuitry in them. If you
>are using an automotive type inverter,
>you will definitely need a blocking
>diode to prevent discharge during non-sun
>hours.
I am curious about this.
An inverter that requires a blocking diode to prevent discharge during non-sun ours?
Why?
I understand that the 20 watt PV module may not produce a high enough voltage to cause the battery voltage to exceed a safe limit at any time. This would of course depend on the size and type of battery and its use. So depending on the battery, there may not be a need for a charge controller but there may be a need for a blocking diode in the PV source circuit instead. Remember a diode consumes power as well, quite possibly as much as the 20 watt module would without it.
I personally have had an array of 6- 77 watt PV modules temporarily bypassing the cc at night without any diodes and the battery monitor reported a draw of only 0.03 amps @ 12 vdc nominal and 0.01 of them is the monitor.

If you would explain the diode for the inverter.

If I were to do this for myself.
More than likely, I would wire the inverter and the PV module to the trucks accessory batteries (assuming it has them.) I would use a charge controller (cc) mainly because of the chance that there would be times when the batteries would be fully charge but not being used and of course the sun was shining. The cc should disconect the PV module when there is no voltage coming off of the module and/or when the battery voltage is high enough.
Even though I might plan on using only one device of a given wattage on the inverter, I would still size the vdc wires for the inverters continuous rated output in watts at the inverters automatic low battery voltage disconnect set point. In this case at least a pair of #8 awg copper wires with at least a 30 amp fuse, #6 if its a long wire run.
A set up like this sould keep the batteries charged via an isolator and the 20 watt panel would provide a trickle charge that would keep the batteries more or less "topped off" when the trucks not running.
Idealy, although not nessessary, the trucks accessory batteries would be true deep cycle and would be used only in an emergency for cranking and the inverter could not pull from the main cranking batteries when the trucks not running but should get a charge from the trucks altenator when the truck is running. A good quality isolator would do all of this. Or if I wanted to challenge my electrical skills I might try to design a system with a dc contactor(s) to do all of this instead.
Putting a fuse between the module and the cc and the cc and the battery is not a bad idea. Allthough some PV modules can have an open circuit voltage higher than what most automotive fues are rated for.

Or I might just mount the module, a fuse, a small cc, another fuse, wire it all into what ever batteries are there, then plug the inverter into a cigarette lighter (if made that way) and go with it.
Its hard for me to say. I would have to actually see what I had to work with to know for sure. Even then I might just have to experiment.
I hope something in this helps. Most of it you probably allready know.
Post back when you've finished. Let us know how you chose to installed it and how it preforms.  

 If some would be so
>kind to help me answer these
>two questions I would appreciate it.
>
>Hypothetically, If I have one 120 Watt
>Panel working at 80% efficiency =
>100 Watts for 10 hrs per
>day. This equals 1 K/Hr per
>day and 30KW/H per month that
>I would not being buying from
>my utility. Is this correct?

No. PV modules typically only convert the energy availible from sunlight into electricity with an efficiency of around 14% to 23% at standard test conditions. When it is at its greatest intensity sunlight strikes the Earth at a rate between 600 to 1000 watts per square meter. Most 100 watt PV modules measure about a square meter give or take. Solar thermal panels, which rely on the infrared spectrum, can reach efficiencies of 80%.

Something more important to consider is the number of hours of equivilent full rated power output per day which is subject to varibles such as; a given region, the seasons, the manner in which the PV module is oriented in relation to the Sun, the number of hours it is in full unshaded sunlight and, the big one - weather.

So to put this into some kind of perspetive. Where I live in eastern NC. solar south is between 7 and 12 degrees west of south on a compass. A 100 watt PV module; mounted in such a way so that a 2"x4" block cut square (about 8" long), placed with its end against the face of the PV module at 12:00 noon on the shortest day of the year (Dec. 21) will cast no shadow and, the PV module is exposed to full sunlight on a cloudless day with no haze, from 8:00 am to 4:00 pm, will produce approx. 350 watt hours.
During the summer on the longest day (June 21) if all I did was lay the PV module down to compensate for the suns higher angle and, weather conditions were the same, the 2x4 block would cast no shadow at 1:15 pm and the PV module would produce approx. 600 watt hours.
The trick is to "tune in" the PV module as close as possible to being perpendicular to the sun at all times of the day but, trackers are not cost effective for all regions or locations. In some case's it would be more cost effective to spend that money on more PV modules.

>As far as components go for a
>interty system I know I need
>solar panels and a intertying inverter
>such as the Sunnyboy SMA 1800.
>What else do I need?

Start by contacting your electric power supplier. Each one has different rules or policiy's concerning how an RE system is "tied on" as well as how they compensate for the power provided from the RE system. You will need disconects between the PV module and the inverter and between the inverter and the meterbase. There may be a need to add a transfer switch as well. Oh! it wouldnt be a bad idea to spend the $40 and get a the most recent NEC handbook and study it, Article 690 in particlar.

Did any of the links I gave you before help? I thought for sure the rendered schematic in the Homepower article about "Solar Cheese" would be helpful. How is your research going by the way?

With the information you gave for power needs and the time of use - 6.5 amps @ 120 volts for the PC and 65 watts @ 120 volts both for upto 12 hours, this would total 845 watts. I doubt that these two items would actually pull this much wattage but I will use this as a base figure.
845 watts for 12 hours equals 10,140 watt hours.
If I assume 24 vdc nominal battery storage then,
10,140 / 24 vdc is of course 422 amp hours.
This would provide power sun or no sun. Under no sun conditions it would kill the batteries as well. It may be necessary to double the storage capacity to stay in the top 50 %. This way the inverter will not shut down due to low battery voltage before the 12 hours are up.
Next would be the PV charge source.
Assuming 4 hours of equivalent full rated charge per day, I would divide 10,140 by 4 and I would get 2,535 watts, which is what the size of the PV array would need to be for a "somewhat" autonomous system that use's this much power for this length of time. Day or night.
Which gets back to what I wrote earlier about doubting a desk top PC pulling that much power. Right now I'am using an emachines with a 17" monitor and its only pulling 10 amps @ 12vdc nominal. Thats 120 watts, ac or dc. That 10 amps will flucuate up and down depending on how white the screen is or how dark (color) it is, but only by a few amps. The television does the same thing.
So you may what to get a meter and find out exactly how much wattage your PC and it accessories will pull. Obviously, to make it all mobile or portable you'll need to keep it all small and light wieght.
It would be interesting to read about the system you put together. How about posting it when you have built it?
Sincerely, Thomas

http://www.dsireusa.org
http://www.sandia.gov/pv
http://www.homepower.com

I bought a Premier SLK gas range a few years ago.
Two problems I had are 1 - the first time I plugged it up it went to clicking and would not stop until it was unpluged. Turns out that a neutral wire on a six pin socket has been misplaced. Easy to fix.
2 - also easy to fix but dissapointing none the less was the oven door hinges. Only one had to be replaced but I replaced both of them. This shouldnt happen after only three years in service.
Other than these two items it has performed very well. It doesnt keep time well but thats because of the 150 watt "pocket" inverter that powers it and the vented/lighted range hood.
You may allready know that some gas ranges come with a "glow bar" that requires a lot (to me) of electric power. If this is a problem go with the electronic ignitor or standing pilot models.

Dont know about the weeds in the pond but, the pv modules might be Solarex Millennia MST-50 or -43.
The MST-50MV 0.688Amps 72Volts both at Max. power. I took this to be the same as Isc.
Framed dimensions as inches, 48.8 long by 26.3 wide by 2 thick. Weight 33 lbs.
Solarex also made the MST-43MV - 0.61Amps and 71Volts.
There was also the MST-50LV and the MST-43LV.
There amps and volts are 2.81A 17.56V and 2.57A 16.67V there frame sizes are all identical as well as there weights.

At a glance I see a lot of intricate mechanisms that would need very precise calibrations as well as lubrication. I did not see any torque or horsepower in relation to rpm readings. I believe that the wheel will indeed keep itself spinning longer than any conventional wheel.
With the aid of magnetic fields instead of lubrication and placing the wheel in a vacuum, this would assist the longevity of the wheels time at spin and its overall time between overhauls.
Marry a bank of these wheels to a super cooled generator and there might actully be something to it. It would seem that "stacking" several of the wheels would be the only way to increase torque and horsepower. Perhaps a large steel flywheel to assist when heavy loads are applied to the generator.
Very intricate.
?Torque and Horsepower at RPM's?
?Whats the scale of this wheel?
None of the answers to these questions was made clear to me from the web site, at a glance.

I think mankinds obsession with energy is a farce. We are being conditioned by those that would have us perpetuate generation of revenues, to precieve of a world, not of a natural order but instead one of a "man made" order. A humanistic world in place of a world of humans and other creatures.
Mankind lived without all of these new world energies for well over 7,000 years. What have these energies really brought? An increase in the rate of increase in global human population? Destruction of the enviroment as well as devestation of natural resources? Not by desire for these things of course, but by the shear number of people alone. I would tend to believe that, no matter what convictions one may hold about the creation of the planet Earth and all the life on it, the Earth cannot support such an unbalance indefinitely. The planet Earth will correct itself, oblivious to those creatures that live on it. I guess we wont know for sure until the end. Will I see you there?  

Almost any PV module will work, the trick is in matching the power output of the PV module to a particular batteries needs.
http://www.cetsolar.com/solarbatchargers.htm

There have been times when I've set out to learn something new. I would read the books and look over the charts and pictures and all of that but then one phrase or sentence would clear it all up and give me the understanding of it all, kind of like, the last piece in a puzzle. Where batteries are concerned it was this: Batteries do not store electricity, the convert electric energy into chemical energy and store that, until such time as electric energy is needed and then it converts it back.
A simple thing that one may know or at least speculate, but until I read that, everything I had read about; lead, spongy lead, sulphuric acid, amp hours, C rates, and the like still had an ora of mystery.
First: know what your electric needs are and translate them into watt hours. Most electric devices that have a UL listing have there wattage labeled on them but some list only volts and amps.
To do this one will need to know the volts and amps or watts that an electric load demands as well as the amount of time the load is on demand.
Example: a 12 volt nominal motor draws 3 amps for 6 hours, mathmatically this is simply 3 x 12 x 6 = 216, thats 216 watt hours. Also a 50 watt light at 12 volts for 4 hours - 4 x 50 = 200 plus the 216 for the motor is a total of 416 watt hours. (It makes no difference when caculating watt hours if its volts ac or volts dc.)
Second: Once one has the total watt hours both for ac and dc loads, translate this into amp hours by divding the watt hours by a nominal battery voltage. Continuing the example from above: 416 divided be 12 equals 35 amp hours.
This would absolute minimum battery storage capacity. Now figure what number 35 is 20% of, because staying in the top 20% of battery capacity increases its overall life and will give 2 or 3 days of reserve power. This would be a 180 amp hour battery at the 20 hour rate. If anything go larger when pricing a battery bank.
Third: sizing the PV array, at minimum I like to size the PV array so that it can replace that top 20% in one sunny day. To do this one needs to know the number of "hours of equivalent full rated charge." Use worst case which would be winter time. If it were 3 hours then, 35 amp hours divided by 3 hours would be 12 multiplied by the nominal voltage which is 12 which gives us a total pv array size of 144 watts.
This is all over simplified of course and bare minimum in example. Allways round up and when actually making a purchase go to the next size up. In the example above where a battery capacity of 180 amp hours at 12 volts is needed "bump" it up to 220 when making a purchase, this is true the PV array as well, where 144 watts is called for in the example "bump" it up to 200.
If you managed to get this far without me putting you to sleep, goto www.homepower.com and read what they all have to say. Out of all the monies I've spent on my of grid system, the best value over all was a subscription to HomePower magazine.