24v or 12v inverter & bank??

silvertop · June 2012

Re: 24v or 12v inverter & bank??

The dip switches dont change the fact that there Isn't 110 power to the refrig. mine is a Samsung side by side and it needs power to run the electronices. I would check with others on this forum about MSW ,my TV wont work with MSW and with the front load washer and the new refrig. I'll stick to the cleaner power. If you ever ran a box fan on MSW you can hear more motor noise. My laptop transformer also runs hot when run on MSW............Now the dips switches do work for somethings,drills,hair dryers ,TV, it just depends, there is a delay before it kicks in kind of hold the trigger untill I't comes on. I also use those timers, and simple plug in timers need some power and that also rules out search mode with the dip switches for me

There are many ways to do all this maybe two inverters ?

Cariboocoot · June 2012

Re: 24v or 12v inverter & bank??

silvertop wrote: »

There are many ways to do all this maybe two inverters ?

Not practical as the refrigerator that needs constant 120 VAC to keep its "brain" going is also going to need the 1kW+ to start the compressor. Without being able to rip the 'frige apart and rewire its sourcing (keeping motor power isolated from the controls) you're stuck with burning 20 Watts all the time to run a big enough inverter to power the compressor when needed.

Bummer. My boring, non-computerized 'frige simply turns on when needed allowing me to leave the Outback in (fully programmable, unlike most) Search mode and save maybe 10 Amp hours per night. :roll:

ywhic · June 2012

Re: 24v or 12v inverter & bank??

Anyone use the Xantrex TRACE TR1524 for example?? anyone have the WAVE from that?? I know its an MSW.. just wanted to see a WAVE or review and I cannot find any on it at all..

I know the Magnum has the MSW <=.0003% thing going.. just wanted to know what the Xantrex had going for it..

ywhic · June 2012

Re: 24v or 12v inverter & bank??

ywhic wrote: »

The other Question.. since I am running a PWM controller and seems like with a 12v system I'm getting 112 w/panel (77%)..
with a 24V system and putting in 18VMP*2 = 36 VMP.. my settings for the bank would be at 28.8 Absorb (flooded).. I'm guessing I'm still losing that same 3.6 volts per panel.. correct?? and be at 672 Watts (112w*6).. (loosing 198 watts)

or would I be a little higher at 691.2 watts (28.8 battery setting * [3 series*2] *8 IMP) (loosing 178.8 watts)..

I'm thinking the higher 691 (which wouldn't hurt me mentally as much..LoL..)

Short of selling the 2 week old TS-45 (PWM) and getting the TS-45 (MPPT).. I think I've done the best I could with what I got..

Cariboocoot whats your take on my proposed number CRUNCH ^^^^

vtmaps · June 2012

Re: 24v or 12v inverter & bank??

ywhic wrote: »

Short of selling the 2 week old TS-45 (PWM) and getting the TS-45 (MPPT).. I think I've done the best I could with what I got..

Al, I have totally lost track of your many threads and many system proposals and changes. It does seem, after much resistance, that you are coming around to accepting the advice that you were given way back at the beginning.

You may have set a forum record for the number of posts involved in setting up a relatively simple system. If you haven't set the record yet, at the rate your system is progressing, you still might.

--vtMaps

BB. · June 2012

Re: 24v or 12v inverter & bank??

Easy guys... We are here to help.

-Bill

vtmaps · June 2012

Re: 24v or 12v inverter & bank??

BB. wrote: »

Easy guys... We are here to help.

I'm sorry. And I do want to help. I guess I'm just frustrated by my own inability to keep track of this system as it progresses. --vtMaps

ywhic · June 2012

Re: 24v or 12v inverter & bank??

I've got it 99% figured out..

I also figured questions by me may eliminate some by other NEWBIES as they can google my same question and be led straight here to the forum.

If I didn't need an Air Conditioner I would have been done asking questions like a month ago..

I did confirm with Morningstar on the phone Friday that the TS-45 will just taper down my extra panel to make the output 45 amps even to the battery bank from 48.3 amps.. (8.05 IMP * 6).. and even set for a 12v system it would be fine..

I've got locked in my head now a 24v setup and bank (was going to buy 2 12v batteries anyway).. and that the 24V battery bank and a 2K 24V inverter should do the trick.. and the 24V inverter draws 1/2 the amps of a 12v setup.. though the wattage coming out is the same.. (see I learned and listened)..

I also will also use the 3/0 wire I had already got for the 12v setup from the bank to the Bluesea battery switch.. then to the inverter.. and I will be using the little Bluesea marine fuses on the battery bank.. the SA-2000K has M8 studs/nuts on it and not the little pins like most of the Samlex..

The other good news is my local HD has not banned me yet from the electrical departments.

Cariboocoot · June 2012

Re: 24v or 12v inverter & bank??

Al, you are right about what happens when you connect the panels in series for a 24 Volt system: you get 18 * 2 = 36. That's more V above the charging point (or even EQ @ 31) and it's power that will be lost on a PWM controller (unless it needs to be used for long wire runs, which isn't the case here). But you will still get the same power as you would with a 12 Volt system as it is dependent on the current @ system Voltage, in this case times 2. This is why higher power systems benefit more from MPPT.

ywhic · June 2012

Re: 24v or 12v inverter & bank??

Yes, I understand.. I calculated my losses to less than 1.5% from panels to the controller.. so MPPT would help me more I am sure than the PWM for the size my system is at..

I was getting about 19.X VDC at the controller last week for 1 panel even when it was over 90' F here.. so MPPT will still help me down in TX..

I'll be selling my 2 week old TS-45 [PWM] (that was used 3 times and never mounted.. and has 1 knockout missing on the bottom) if anyone is interested PM me.. I'll be letting it go for $130.. shipped to US lower 48 only.. just got to get the last 145 w panel ordered up this week hopefully.. then I'll have 6 panels and can do the 24v system..

Figure after the sale of that and saving for a month I can then get the MPPT version of the same..

ywhic · June 2012

Re: 24v or 12v inverter & bank??

Using a 24v bank and the silly MS calc..

It says I can go 3 different ways..

1 string parallel of 6 modules in series
2 strings parallel of 3 modules in series
3 strings parallel of 2 modules in series

Thinking 2 strings of 3 each would work best for my proposed 'ground' layout.. easier to troubleshoot then the next option below..

Unless you think the 1 string of 6 would be better for some reason?? I dunno.. up one side of 3 and down the other side of 3..

What numbers could I maybe expect from the MPPT??

MS Calc for temps of 0'F and 115'F Max temp says for 1 module:

22.17 Max VOC
16.4 Min VMP @ High Temp
18.57 Max VMP @ Low Temp

Photowhit · June 2012

Re: 24v or 12v inverter & bank??

I'll try, with out getting upset...

Go back and read,

Go Back and read!,

GO BACK AND READ!

When you don't, people will feel like you have wasted their time, and may quit responding, I know I have in one thread.

Panel voltage will decrease as panels get hotter, will you get a boast in production? YES, but not as much as buying 2 more panels, the difference in cost betweet the 2 inverters.

I know we have been over this and others have concured. If people stop responmding yo may be left with the wrong impression.

Jim45D · June 2012

Re: 24v or 12v inverter & bank??

Al is simply like myself. Not too sure, but still trying. Finally it dawns, as it did me....what the H... am I doing wrong? XYZ thread say's that it'll work.....then they aren't sure either! Then what? Back to the drawing board. Sorry, but some of us just aren't whizzes at this.

mike95490 · June 2012

Re: 24v or 12v inverter & bank??

ywhic wrote: »

....What numbers could I maybe expect from the MPPT?? ...

If all 6 panels in series, does not violate the high voltage spec of the MPPT controller, you can
expect 95% of the input power, being available at the batteries, if they need them.
When the batteries will no longer need the MPPT boost, the controller falls back to PWM mode.

* input power can vary greatly from day to day, under seemingly identical conditions, temperature and atmospheric haze being major ones, followed by sun angle.

Also, heads up on the MS controller, the 45A does not come with the fancy logging info the 60a has, and neither has built in meter. That's what's tilting my next choice of controller toward being a Midnight Classic.

BB. · June 2012

Re: 24v or 12v inverter & bank??

From a technical point of view, as long as Vmp-hot is higher than ~31-32 volts or so, and Voc-cold is less than Vmax-input for your controller--It does not matter.

MPPT function will make all configurations virtually the same from the battery bank's point of view...

Now some things to look at:

Check the efficiency of the MPPT charge controller... Vmp-array vs Vbatt voltages... Different vendors have different curves (because of design trade-offs). For example, one major vendor seems to have maximum efficiency of if Vmp-array=2xVbatt (check the controllers you are looking at and see if there is significant differences in efficiencies).
When you have 3 or more Panel strings in parallel, you should have a combiner box with fuses/breakers--one per string. This adds complexity and cost to the system--And fuses/breakers are a bit on the unreliable side (i.e., they are designed to "fail" at currents a bit above "nominal"--so that makes sense--temperature, humidity, age, all affect fuse/breaker life). Doing a 2 or 1 string array can save costs.
Note that if Vmp-array-hot is near Vbatt-charging, you may have difficulties reaching maximum array output due to Vmp depression (due to heat) and a cool battery bank. Running at least three panels in series will erase this issue (Vmp-array>>Vbatt-charging under all conditions).
Running arrays at Vmp-array approaching Vmax-input--There is the possibility of a very cold night (with radiative cooling) to over voltage the input of the charge controller (you have to do the calculations). Over voltage stresses transistors/electronics. They may not fail immediately, and they even may fail years later--Just make sure you have enough "margin" that your 6x array does not damage your controller (desert type areas have much wider temperature extremes than somebody with an array on an island in the Caribbean).
If you make a 6x string, if you want to add another panel or 2 or 3, you cannot. You have to break the array up anyway (assuming the controller can manage the extra current)... If you do a 3seriesx2parallel array, you can add 3 panels later (just get a combiner with room for extra breakers/fuses).
Obviously, high Vmp-array allows you to place the array farther from the controller/battery bank while using smaller gauge wiring. We have been down that road before.

Those are the points that I ponder when suggesting system configurations.

I probably would suggest 3seriesx2parallel as it would allow you to add more panels in reasonable amounts later.

The 6x1 string might be too high of Voc-array-cold for any 140-150 VDC max input controller unless you have warm/moderate winters. Is Voc-cold=22.17 at 0^oF correct?

-Bill

niel · June 2012

Re: 24v or 12v inverter & bank??

i did reply once here and deleted it, but on 2nd thought i'll say it anyway. unless you have great wire runs the 2p x 3s is the best arrangement. even though 2 pvs in series actually will work, it will have problems if say a small amount of shading occurs or temps drag the pv voltage down too far so a bit of extra voltage (aka adding one more pv in series to the base bottom amount) is desirable. so why not do all in series anyway? because it is possible you are unnecessarily adding conversion losses, for the higher the input to output voltage ratio is the larger the conversion losses (lower cc efficiency) will be. it is another one of those general rules of thumb to just add 1 more pv in series to the lowest working series pv arrangement. as with all rules of thumb don't take it that literally because many of the oddball voltages out there make this a rule of thumb that can be violated easily and still get good results. i'm speaking of the pvs that are now around 29v-30v vmp and aren't good for a 24v battery bank on its own merits, but 2 works great in series because there is a great deal of extra leeway there with just the added 2nd pv that would work for the 24v batteries. now if one went to a 48v battery bank using the same pvs in that same vmp area then 3 in series would do nicely.

Cariboocoot · June 2012

Re: 24v or 12v inverter & bank??

Remind me to write this up sometime, guys. I had been thinking about adding another theoretical example to the heap that would explain exactly this, right down to the six KD panels.

Two strings of three would be my pick: three strings of two require fusing on each string and I'm a lazy cheapskate.

Photowhit · June 2012

Re: 24v or 12v inverter & bank??

3 Moderators responded, any of you take 6 panels on a MPPT charge controller over 8 panels on a PWM controller when your major load will be an AC in Texas heat?

Or have you all gotten tired of helping Al, and just answering the current question?

Cariboocoot · June 2012

Re: 24v or 12v inverter & bank??

I believe he's decided to sell the PWM, sell a kidney to buy a MPPT controller, and squeeze the max out of 6 panels for a 24 Volt system (6 * 140 = 840 * 0.77 = 646 / 24 = 27 Amps or 270 Amp hour battery bank).
Something like that, anyway.

ywhic · June 2012

Re: 24v or 12v inverter & bank??

BB. wrote: »

The 6x1 string might be too high of Voc-array-cold for any 140-150 VDC max input controller unless you have warm/moderate winters. Is Voc-cold=22.17 at 0^oF correct?

-Bill

BB

The VOC 22.17 is for the 0'F.. yes. correct.

The VMP is 16.4 @ 115' F.. so multiply by 2 and you have 32.8.. * 3 and you'd have 49.2 :cool:

Photowhit.. after all the huffing to get more panels and run PWM.. I'm thinking I want to MAXIMIZE my 870 watts.. and not loose 180 watts to the PWM..

Thanks Mike90045..

I have the TS remote 2 meter here from the TS45 I plan on keeping that..

I thought the TS45 MPPT and TS60 MPPT both have logging on them if I use the meter (have to call on that)...

I am leaning toward the 2 parallel strings of 3 panels.. (the max VOC for all 6 in a row would have been 111.. not near the 125 VOC rating..)

Cariboo.. I'll still use that combiner box no matter which route I go.. better safe than sorry and I already have it..

Am I going to gain anything with the MPPT over the PWM.. your saying it will be 77% either way??

Cariboocoot · June 2012

Re: 24v or 12v inverter & bank??

ywhic wrote: »

Am I going to gain anything with the MPPT over the PWM.. your saying it will be 77% either way??

PWM controller: max current = Imp of panels * number of panels. As: 7.7 Imp * 6 panels = 46.2 Amps.
MPPT controller: max current = Watts of panels @ efficiency of array & controller (typically 77%) / nominal system Voltage (minimum Voltage). As 6 * 140 = 840 Watts @ 77% = 646.8 / 12 = 53.9 Amps. Or 16% increase in peak charge current on a 12 Volt system for the same array.

Didn't I just write that? It's déjà vu all over again!

niel · June 2012

Re: 24v or 12v inverter & bank??

Photowhit wrote: »

3 Moderators responded, any of you take 6 panels on a MPPT charge controller over 8 panels on a PWM controller when your major load will be an AC in Texas heat?

Or have you all gotten tired of helping Al, and just answering the current question?

photowhit,
i responded late on the assumption he wanted mppt. what you are saying of going to 8 pvs with a pwm cc instead of 6 pvs with an mppt cc, to me, is viable as this is putting the extra $ that would've gone to the mppt cc now into pvs instead. not as efficient, but more overall amps. the pwm he has will not pass more than 45a though and 8 pvs at imp 8.05a is 64a. he would need another cc to do that as the 45a pwm cc will throw that current away over 45a. if he had gotten a 60a pwm then i'd say it's a go as there won't be too many times he'll get the full imp to fold back the current being we derate it to 77%. or 64a x .77 = 49.28a

if the thread upsets you can then walk away from it as it isn't worth blowing a gasket over. or take another shot at it with another approach. that's about all you can do, but if somebody wants to do something that isn't as cost effective in your eyes, then they are free to do so as it is their decision to make.

Photowhit · June 2012

Re: 24v or 12v inverter & bank??

ywhic wrote: »

Photowhit.. after all the huffing to get more panels and run PWM.. I'm thinking I want to MAXIMIZE my 870 watts.. and not loose 180 watts to the PWM..

Sorry this is not accurate. I've done the math for you before. When you've been off grid for 10 years, then you can tell me I'm wrong.

Cariboocoot · June 2012

Re: 24v or 12v inverter & bank??

What Photowhit is trying to point out is that due to the high temperatures in your area the panel Voltage will be lower than the STC rating. Therefor the extra power the MPPT affords from the higher Voltage potential will likely not be realized.

There certainly would not be a 180 Watt loss between the MPPT and PWM controllers.

Nor is it an absolute that one controller would be better than the other, as the MPPT may offer more charging in cool morning light. Try to keep in mind that a maximum potential is not the same as "absolutely this much power" in either case.

Is MPPT worth the extra money? That is up to you. Photowhit does not believe it is in your case.

And I'm getting a bit tired of editing posts for their adversarial nature of expression.

niel · June 2012

Re: 24v or 12v inverter & bank??

i'm regretting jumping in here late myself. the point of the temps is a valid one and may bring the efficiency down further with either controller so the present cc with 8 pvs may work for him during the heat of summer. he loses the extra in winter though.

ywhic · June 2012

Re: 24v or 12v inverter & bank??

Well with the 24V and MPPT I can go with the above 2 strings of 3 panels.. with the current PWM I can only do 3 strings of 2 (which is no biggie).. (according to the MS calc.).

I'll stick with the PWM.. I was figuring the extra boost but 10-15% isn't worth $300 extra for the MPPT.. (Sorry Photo for aggravating you)...

silvertop · June 2012

Re: 24v or 12v inverter & bank??

ywhic wrote: »

Well with the 24V and MPPT I can go with the above 2 strings of 3 panels.. with the current PWM I can only do 3 strings of 2 (which is no biggie).. (according to the MS calc.).

I'll stick with the PWM.. I was figuring the extra boost but 10-15% isn't worth $300 extra for the MPPT.. (Sorry Photo for aggravating you)...

Just to add my two cents in, I'm not sure ywhic if a MPPT is justified but I can tell you from my perspective, that the ability to run significantly smaller guage wires a greater distance has been a great benefit. I think most people should look at it from the simplistic installation point of view and the added 10-15% charging is icing on the cake. I started off with 12V and a simple 'on/off' controller. Probably, like a lot of people on this forum, have learned over the years from my mistakes/improvements. I wish I had started with MPPT controllers first. For me they have been a great benefit.

ywhic · July 2012

Re: 24v or 12v inverter & bank??

Got my panel number six ordered. Getting there.

ywhic · July 2012

Re: 24v or 12v inverter & bank??

Ok..

I checked on the Morningstar and Midnite Classic calculator sites using my panels number and co-eff rates and such.. just to see how my 115' F temp works out with MPPT..

From Midnite Classic I got this information:
Rated PV Array Power: 870 Watts
Anticipated Array Power @ 115F: 787 Watts
Rated PV Array Current: 24.15 Amps Battery
Charging Current @ 28.8 V: 30.2 Amps
VMP (Maximum Power Point Voltage) : 36 Volts
VOC (Open Circuit Voltage): 43.2 Volts
VMP @ -10 F°: 43.8 Volts
VOC @ -10 F°: 44 Volts

And Morningstar String Calc said 32.796 VMP for 2 panels at the same 115' F.
which at 8.05 IMP would work to 792 watts..

Now my 10 AWG wire comes up to 1.03% loss for the 15 run for 2 panels.. on the short run I get 0.55% loss.. so those numbers look good..

Marc from Rogue said (via several emails) if I did a 24V bank and 24v panels I can use my PV setup with his controller as well.. at $325 and with the nice display that shows in/out numbers (not like my current MS TriStar meter). that may end up being the winner.. He said in the HOT heat I may only see single digit % gains though.. but in the spring/fall/winter I'd probably better than with the PWM I have sitting here.

Decided to sell the TS45 (PWM) controller with RM 2 Remote meter for $229 shipped in the sale section on here if anyone interested..

Now if Samlex tech support would stop saying an MSW inverter for an Air Conditioner and stop trying to sell me a 3000 w inverter for $1000+ I'd be in alot better mood/setting to go with 24v.. Their saying the Pure Sine SA-2000W Cont/ 4000W Surge unit may be under rated to crank that 21.4 amps I would need to kick my 5K Air Conditioner on.. even though my gut is telling me the K series can do this..

If Xantrex or someone else can make a decent Pure Sine inverter for about $600 that will do the job I'm all ears folks..

The Xantrex ProWatt SW2000 is $340 or so.. and per 2ManyToys can do the job.. buts its only 12v..

Very frustrating..

solarvic · July 2012

Re: 24v or 12v inverter & bank??

Have you thought of an exeltech 1100 unverter? You could download the manual. In it it explains how many watts over 1100 watts the inverter can safely handle for the people that actually read the manual. Solarvic

24v or 12v inverter & bank??

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24v or 12v inverter &amp; bank??

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24v or 12v inverter & bank??