solar panel ratings

PTC rating

Looking at the different panels, it seems that there is about a 10% difference between the panels rated output, and the PTC rating...of course, it varies with the mfg's...the higher dollar panels seem to have a VERY slight gain on PTC rating....but is the slight gain worth the 40-60% increase in price? I know i stated that my system would be 1500-2000 watts, but if i can buy panels at .78 cents to $1.14( at the links you gave), it might save me some grief to order 10 panels....either increase array size, or save 2 or 3 for future add on or bad panel replacement.????? I trust your opinions and experience.....or would i be smarter to buy the 8 panels, and put the savings into the Outback charge controller and inverter i'll need???? If'n this was your money , what would you do? Thanks again for all the help....it stinks being a newbie!!!! rsbhunter

 

Is a slight gain worth 40% ? Probably not, in my book.

You really have to decide WHAT your needs are and what your budget is.

In my opinion, you're going to need a GOOD quality charge controller and inverter, like the Outback, and DO NOT go cheap in that area. Their pre-wired power boards with all that on it are the BEST way to go, again IMHO......they save you trying to figure out which components to order, how to put them together, and so on....you can stumble around for a LONG time trying to get all that right ( I did ).....and even then have to come back and make changes. The seemingly "extra" you'll spend on the pre-wired board isn't extra at all.....it's all the stuff you don't even know you need at first ! ( The DC breakers, the ground fault, the AC breakers, the Hub, the temperature sensor to the battery, and so on and so on....).

On the panels, buy what you can.....you need to match enough panel to your battery bank size to assure you charge it properly, but also allow for expansion. For example:

The cabin in the link above, my buddy put 6 panels, along with a 3 space combiner box up near the panels. I wired the panels in strings of 3, at 90+ volts, which uses 2 of the spaces in the combiner box ( 2 strings of 3 panels ). Since his roof is fairly small ( that hip roof ), that used all the mounting space on the south side for those 6 panels. IF he needs to add more, it will have to be on the west or east roof face, and he can add 3 more, using that other space in the box, and make no other changes. That would up his panel from 1470w (245 x 6) to 2205w (245 x 9). But what we've found so far, for his use, is he has plenty at 1470. He also has a good Kubota diesel genset should he be staying up there for extended bad weather.

 

And as the battery decreases in voltage down the 10v cuttoff the specs call for on this inverter, the amperage would rise...to 1000 AMPS at full wattage.

Mr. Nobody.....I'd REALLY REALLY like to see how you have this connected along with the fusing and wire size....you still out there ?

Photos would be great !

I emailed the inverter company and asked what cable size the inverter is capable of accepting on the battery side, since that isn't on their loose set of specs. 800amps in would need something like 750MCM copper wire....which is right at 1" diameter wire....that's a HECK of a lug to take that.

 

System i'm thinking of

Ok, i'm pretty much set on getting 10 Canadian solar or Solar World panels,(as long as i get a consensus that they are decent panels and NOT junk), the Outback Flex power FP1-1 and probably L-16 6volt Trojan batteries (8), unless i can afford better at the time...This should keep me in the $10,000 range.......Will the outback Flexpower handle the 2350 watts and 70-80 amps the panels will put out? I know i can live within this system easily, it MIGHT be overkill....better 2 b safe than in the dark...rsbhunter

 

Just make sure you spec an FM80 for the charge controller.....it will handle 80amps, and 2500w of panels configured at 24v output, or 5000w configured at 48v output. ( the controller is field programable for 12-60v output, but if you order it on the power panel, it will come already set up based on the inverter you pick )

So, you will also have to specify whether you want a 24v or 48v inverter, as well as the wattage. I put a 24v 3500w one on my buddies install, but I'd probably consider the 48v 3600w one now. Going to 48v, you can cut the wire size in 1/2 on the panel to battery run, and the wiring is more simple on the batteries since all 8 are now in series, and you just need one positive and one negative wire from the ends of the bank.

The FP1-1 is the 24v panel, the FP1-2 is the 48v version.

http://www.wholesalesolar.com/inverter-system/outback-power-flexPower-solar-power-center-fp1-2.html

(See that little install pic....hang the bracket, hang the whole panel.....1/2 hour job )

Also note, get the generator auto start feature, assuming you have an electric start generator, so when the battery voltage dips to a level you select, it automatically kicks in and charges your batteries back thru the inverter....a VERY handy feature !

The only other piece of equipment I'd recommend is a Trimetric battery monitor ( Don't buy the Outback one....it's just a set of green LEDs to give you the battery level )....the Trimetric....Bogart Engineering....is a MUCH better meter in terms of information about your system. The panel comes already set up with a shunt for the Trimetric.....all you need is some 18ga wire run from the power panel to a easy to read place in your cabin ( I put my buddy's on his kitchen wall, since the Outback stuff/batteries are in the basement )

 

Great posts. What is everyones opinion with solar in the northeast USA?

 

solar in the N.E.

Ok, my first reply to a question....and site members, PLEASE feel free to jump in and correct any inaccurate info i give....First, decide what kind of system you want, grid-tie, stand alone...then go to google and search for a map that shows how much sun that location recieves each day. Then, figure out what you want to run off of solar, how much power you will use in a day(if not grid tie) , what you can afford to spend, and the most important thing to remember is (as many wise people have told me) "you need to live within your systems limitations, as your system won't adjust to your expections" Thats probably half of what you need to supply for info, but is a start....The people on this site are wide open to helping, and have a wealth of info.....do as much reading as you can, i think it's Wholesale Solar site that under "information" gives some good guides to what YOU need to decide on before the guru's here can steer you in the right direction....just my .02....rsbhunter

 

Outback system

Ok, that makes sense...if i go to 48V system, do i need to up the voltage output on the panels, or just wire in series? As most of the panels put out approx 27- 29V, that would put the volts at close to 60V, correct? Will i need to double my battery bank from 8 (2 banks in series/parallel) to all in series (8/6 volt batteries), and being 48V, how does that effect the aH capacity of the batt bank, or is the ah draw lower with a higher volt system ? My questions may not make sense??????? Thanks again to the solar gods that call this forum home!!!!!!!!!!!!!!!!rsbhunter

Just saw these, is this what i should go to? http://www.ecodirect.com/Canadian-Solar-CS5P-250M-p/canadian-solar-cs5p-250m.htm

 

Correct, you wire in series strings. ( might as well learn the lingo )

The Outback charge controllers will accept up to 150v in ( less some de-rating for the coldest conditions in your location when panel voltage will increase....so figure maybe 120-130v in CO ).

Then you take the max voltage rating from the panel ( VOC ) and you can "string" (in series) enough together to hit that derated voltage input.....generally that will be 2-4 panels if you're using high watt panels ( like over 200 ).

You want to make your string voltage EQUAL, so you also have to consider the total number of panels you plan to use.....for example, say you want 10 240w panels with a VOC of 36v. IF you string 4 of them together, giving you (4x36) 144v in, that would work, being under the 150v CC limit ( for Outback ), BUT if you get a real sunny, clear, cold day in your area, you might easily run over that 150v limit, and harm the CC. So 4 would only work in a warm climate, like South Florida.

So, then 3 would be the max.....BUT with 10 panels in your system, 3 doesn't divide evenly....you'd end up with 3 strings of 3, and one odd panel.....that won't work.

SO, 2 is the "magic" number in this case.

Should you LATER decide to add a couple panels, you could reconnect the strings to come up with 4 strings of 3 rather than 6 strings of 2, but that would be up to you.

One of the MAJOR advantages of using an MPPT controller is that ability of the controller to take a much higher input voltage, and step it down to whatever your battery/inverter voltage is going to be, and turn the extra into amps ( you don't loose the extra ). Wiring panels in strings gets your voltage up, as you can see, and makes for less voltage drop ( and power lost ) from the panels to the location of the charge controller, and let's you cut the wire size as well. That run is usually the longest distance in the whole system, as you generally mount the CC right near the batteries and the inverter(s) is a close at hand as well.

DO be aware that any shading on a string pretty much kills the output of the WHOLE string....generally not too big a problem in off grid systems, because the strings are small ( number of panels in one ), but in grid tie systems, strings are WAY bigger, as most grid tie inverters need 250-300v to even come online....strings in those type inverters often run in the 400-500v range.....many, many panels....and one tree shading a corner of ONE panel can kill a LOT of power production.

Yes to both. You do wire all 8 batteries in series rather than 2 strings of 4ea.

And yes, that cuts the amp/hr rating of the whole bank in half.....8- 6v 400amp/hr batteries in series is a 400amp/hr bank @ 48v....you always want to keep the VOLTS in mind as well as the amp/hrs, because the two give you the total watt/hr the bank is capable of producing...which is exactly the same whether you use 800@24 or 400@48.

The ADVANTAGE of stepping up to 48v is lower wire/fusing requirements ( less$$ ), and the system with the lowest number of strings ( 1 versus 2 ) is the most efficient for technical reasons of battery construction.

No, actually you have a pretty decent grasp on the process.

You certainly CAN use those, with the understanding that you will DEFINITELY have to use an MPPT controller, and string two of them together for a 48v system. A 48v panel does NOT have enough voltage output to charge a 48v battery ( odd as that seems ).....you'd need about a 54-58v volt panel if you wanted to use them single ( all panels in parallel )....same way your car alternator puts out about 14v (or more) to charge the 12v battery in your car.

As you study panels, you'll notice most "12v" panels ( usually 150w or less ) have a Vmp of 17-18v. And most "24v" panels ( 150-250w ) have a Vmp of mid 30v range. Panels came along before the invention of MPPT charge controllers....and that WHY the configuration of them developed the way it did. Now, with MPPT controllers ( and grid tie ONLY systems have MPPT built into the grid tie inverters ), there are all kinds of what would have been "oddball" panels in the past being built.....panel voltage almost doesn't matter ( except for the number of connections, and shading factor I mentioned above ).

If you look closely at the ad for that panel, you'll see it says "For grid tie systems".....meaning no batteries involved.....and meaning, as I said above, you'd be stringing many of them together.....like 8-10.....in series.

When you get into grid tie systems, you can get into some SERIOUS voltage issues, and really need to know what the heck you're doing to keep from frying yo a$$ or burning things down.

Hope this helps.........I put a lot of info here, study it careful. There will be a test later.

 

Fog is lifting....

Ok, so i run 10 230 watt panels, wired two in series/5 strings, into a combiner box at the panels, then the wiring (74V appro, 460 watts per series) into the Outback Flexpower (48 volt setup) then to a battery bank of 8- 6V wired in series.....The wiring at the combiner box will be 5 series of 2 Panels wired in parallel , with the wiring going to the charge controller of the Flexpower FP1-26....Now the dots are starting to look like a straight line, Thanks to all of you on this site.....Are the Canadian Solar panels a useable panel, is there any reason why i might choose a different panel? (like there junk!!!) I am using my uncle sam money (tax refund) money to order the panels, so i do want to get the best for my money.... Thanks rsbhunter

 

I have no experience with the Canadian Solar panels, since I picked Solarworld ( mostly because they are USA made, and I try to buy USA whenever I can ), but on the flip side, I've never heard a complaint about them either.

My guess is if they were a "bad" panel, the internet would be full of complaints about them.....spend some Google time and see what you come up with.

 

Canadian Solar

Ok, unless i hear different from someone, i plan on buying 10 of the CS6P-230 panels from SunElectric, as soon as my uncle sam money gets here...i looked on Google, and other forums (bad juju being there) . Didn't find anything negative....I would love to buy an American made product, but honestly, at the price, it's ALMOST 2-1 cost wise...and that money can be used on the outback system......I wish it didn't have to be in stages that i buy this stuff, but it will get done...Thanks, rsbhunter

 

rsbhunter, I have been doing some research on Canadian Solar, and this is what I came up with. As far as I have been able to tell, ALL of the canadian solar panels are made in China. The company was founded in Canada for the "Cloak" but ALL 7 manufacturing co's are scattered all over China,. The company was founded by a chinese canadian in canada. Here below is a direct copy and paste from their own co.

Canadian Solar is a Canadian company with global reach

With our headquarters in Kitchener, Ontario and seven wholly owned manufacturing subsidiaries across China, Canadian Solar successfully operates its solar PV business in nine countries with a total of 260,000 sqm of facility space. Our businesses in Canada, China, Germany, Italy, Japan , Korea, Spain and USA focus on delivering the highest quality solar produc ts at the highest possible returns on investment to our customers around the world.

 

NADJA

Thanks for the info, i'm not 100% thrilled with buying chinese, but from the research and reading about other people that own panels made there (china), it's a chance i'll have to take...at the price they are right now, i can afford to buy all 10 at once.....Of course as soon as i do, the price will drop to .50 cents a watt!!!!!!!!!!! (my luck). How is the weather there? It looks like it might start to warm up a little here next week, you've had it rough. I have a buddy that lives in Grants, NM. and they have some of the lowest temps anywhere in the state!!!!!.......Again, thanks for your help, and all the others, i'm sure it's a pain to explain the same thing over and over to us newbies...but, i promise to return the favor as soon as i have as much knowledge as yourself, TnAndy, BTPost, and the others... but there are always the "pillars" of the forum that are willing to take the extra minute, and count to 10, before answering some of the questions that are asked by us beginners.....For those pillars, i say again, Thank You, and know that the good you do IS appreciated, and will be passed on for years to come....rsbhunter

 

rsbhunter. You are most welcome sir. Hope it helps you out on your decision making. Cold here also, but looks like it may finally warm up next week or so . Hope so, my snow coverd dirt roads are really bad to drive on.