Which inverter for 12V??

ywhic

Re: Which inverter for 12V??

Stick with 12v for a start.. got it.. (and the panels are abit smaller and lighter I noticed too..)

The good news is I found a 3.3gpm Shurflo water pump that draw 0.9 amp @ max at 110v for $90.. and the same 45-50psi.. while serching for a 24v water pump in the last 20 minutes.. or I can stick with my 12v Shurflo 2.8gpm and upto 7amps.. << better choice..

Photowhit

Re: Which inverter for 12V??

Sorry, I'm not saying stay with 12 volt, only wanted to point out the advantages of the larger panels.

I had ran abck to the forum, as I recall that the Rogue controller, I don't think can handle 2 of the @30V panels in series and the VOC gets too high. (I could be wrong my mind bounces around a bit and I'm trying to get ready for work.)

Cariboocoot

Re: Which inverter for 12V??

Rogue's maximum input is 60 Volts, darn it.

Photowhit brings up some very important issues regarding higher system Voltage, namely the fact that many "24 Volt" panels have a Vmp too low to be useful on a 24 Volt system without being run in series on an MPPT controller. And as the specs on the Rogue point out, this can make the system suddenly much more expensive.

Panel companies favour the GT market where a Vmp around 30 makes sense as they normally have arrays running 250 to 500 Volts. That's why these panels are often the cheapest per Watt: more production & sales brings the price down. Unfortunately it makes things more difficult (and expensive) for off-grid applications. Take $1 per Watt off the panel price, and then have to spend an extra $250 for the MPPT controller (based on MS 45 Amp controllers as an example; you could spend even more money). Worth it if the array is large enough. Small system? Probably not worth it.

But 12 Volt systems don't work well with heavier (over 1000 Watts, say) loads.

silvertop

Re: Which inverter for 12V??

I had the Xantrex SW 1800 12v inverter Its a good inverter. I now run Cotek Inverters 24-7 I am very impressed with these they have good surge rateings, they ARE Samlex inverters but lower cost. You would be much happier if you could run 24v in the end. I have not tried my AC on these yet( TOO COLD) but my Cotek S 1500-24v runs my entire house, It will run 1600watts/ (surge 2000w) and not skip a beat...:cool:

ywhic

Re: Which inverter for 12V??

2 panels at 210w @ 24v.. works to 24vx7.11amp= 170.64 x 5 hours = 853.2 x 2 = 1706... for $800 total.

440 Amp hours @ 12 Volts = 5280 Watt hours DC, up to 50% usable
220 Amp hours @ 24 Volts = 5280 Watt hours DC, up to 50% usable

Power consumption for AC Watt loads is the same on either system, only the Amps goes down and the Voltage up.

A 24 Volt system is about 1% more efficient and can handle heavy loads better because less of the power comes as Amps (which creates heat energy that does no work). Wiring can be smaller and less "stressed".

The panels are rated at 30v and 7.11 Amp according to the website..

Would 2 of these to 'start' with work on the Morningstar MPPT 45 controller?? (I'd be wiring into combiner box like before)

Would I technically be able to draw (if I wanted to try) my 55amp/hour for 1.5 hours from the battery bank??

And I forget.. is it still 12v output with 24v input at the panels with that controller??

Cariboocoot

Re: Which inverter for 12V??

ywhic wrote: »

The panels are rated at 30v and 7.11 Amp according to the website..

Would 2 of these to 'start' with work on the Morningstar MPPT 45 controller?? (I'd be wiring into combiner box like before)

With an MPPT controller you can use most any type of panel providing the input has above the minimum Vmp for the system Voltage and the Voc does not exceed the controller's maximum. The output "takes care of itself".

Would I technically be able to draw (if I wanted to try) my 55amp/hour for 1.5 hours from the battery bank??

This depends on the battery bank mainly. If you're wondering whether or not the panels would compensate for the 55 Amp draw, it's pretty much a matter of 420 Watts of panel (210 Watts * 2) divided by 12 Volts = approximately 35 Amps peak current. You probably won't see that much and obviously it's not enough to cover the 55 Amp draw.

And I forget.. is it still 12v output with 24v input at the panels with that controller??

Yes. MPPT controller can take higher than system Voltage in and use the difference to increase the available current out. I have a "48 Volt" array that runs around 70 Vmp and nicely recharges my "24 Volt" system at about 29 Volts through the MX60 MPPT controller.

ywhic

Re: Which inverter for 12V??

So in the book on page 18 it says..

Switches 2 & 3: System Voltage
Four (4) system voltage configurations are available as shown in the table below:
System Voltage Switch 2 Switch 3
Auto OFF OFF
12 OFF ON
24 ON OFF
48 ON ON
The “auto” setting allows the TriStar MPPT to detect the system voltage automatically on start up.
The test is only performed at start up and the detected system voltage will never change during
operation.
Generally, it is best to choose a specifi c system voltage. The auto detect feature should only be
used in situations where the system voltage is unknown ahead of time or in systems where the
system voltage may change periodically.

Is this for the PV input voltage or the battery voltage?? I'm thinking panel voltage...

This means if I go with the MS TS-45MPPT controller I can run 24v panels and still use my '12v' battery banks of total of 440ah correct?? Just wire 2x6 in series and then parallel the 2 sets to make 12v total and 440ah..

Then I can still run my 12v pump for my water and get a little more ummph out of the batteries with playing..

And I could technically add if I want 2-12v panels (per say in series to get 24v (aka 36v)) and then drop them as another.. though I won't..

The MS TS-45-MPPT is only $395 vs. the $189.. the $280 in panel savings makes the $200 difference not so hard to swallow.. The meter is another $100 so it balances that out..

This sound about right?? What do you think??

Cariboocoot

Re: Which inverter for 12V??

ywhic wrote: »

Is this for the PV input voltage or the battery voltage?? I'm thinking panel voltage...

No. "System Voltage" is the nominal battery Voltage, not the array Voltage. In your case 12 so "OFF ON"

This means if I go with the MS TS-45MPPT controller I can run 24v panels and still use my '12v' battery banks of total of 440ah correct?? Just wire 2x6 in series and then parallel the 2 sets to make 12v total and 440ah..

Yes, the MPPT controller can use "24 Volt" panels on a "12 Volt" system. Since you will have two strings of batteries in parallel, be sure you make all negative system connections to one string and all positive system connections to the other. That way is best to be sure the current going in and out is shared equally between both strings.

Then I can still run my 12v pump for my water and get a little more ummph out of the batteries with playing..

Not sure what you mean by that.

And I could technically add if I want 2-12v panels (per say in series to get 24v (aka 36v)) and then drop them as another.. though I won't..

Depends on how you do it. With the right Vmp on the 12 Volt panels they could be put in series and then paralleled to the 24 Volt panels. Or you could use a separate controller.

The MS TS-45-MPPT is only $395 vs. the $189.. the $280 in panel savings makes the $200 difference not so hard to swallow.. The meter is another $100 so it balances that out..

That's why you have to work out several different system designs that meet your needs and then weigh the advantages and disadvantages. It can be really aggravating trying to make that final decision and spend the money. You're always wondering if you should have gone with the "other one", especially if performance doesn't live up to expectations.

This sound about right?? What do you think??

I think I spent about $8,000 on my system and have plans for a $3,000 "upgrade". Does that make you feel better about yours?

ywhic

Re: Which inverter for 12V??

Cariboocoot wrote: »

I think I spent about $8,000 on my system and have plans for a $3,000 "upgrade". Does that make you feel better about yours?

Yes.. I figured $2500 for 630 watts if I go with 440ah in battery bank (4 T-105's) using 3-24v panels vs. the 4-12v panels 560watts.. An extra $400 on top of the 560 watt plan.. but worth it I am sure with the MPPT 45 controller and 24v panels..

So wire them like this, correct ..>>

Attachment not found.

Cariboocoot

Re: Which inverter for 12V??

No, the negative needs to come from the other string.
Like this:

Photowhit

Re: Which inverter for 12V??

Dang the math thing...

MPPT charge controllers are based on Amperage out put, 630/12=52.5Amps, very likely you'll never see that, but if you fry it's on you.

Another nice thing about higher voltage systems 630 /24 = 26.25, the trick here is that I don't think the TS 45 can handle a string of 3 of this panels with a VOC of 45, so 4 panels for a 24 volt system or move up to a MS 60 for a 12 volt system...

ywhic

Re: Which inverter for 12V??

Photowhit wrote: »

Dang the math thing...

MPPT charge controllers are based on Amperage out put, 630/12=52.5Amps, very likely you'll never see that, but if you fry it's on you.

Another nice thing about higher voltage systems 630 /24 = 26.25, the trick here is that I don't think the TS 45 can handle a string of 3 of this panels with a VOC of 45, so 4 panels for a 24 volt system or move up to a MS 60 for a 12 volt system...

The 210 w 24v panels are 30v and 7.11 Amp maximum numbers.. 3 would be 21.33 amps @ 24 v.. which if *2 would be 42.66 amps @ 12v unless I figured the numbers wrong..

Would 24v 190w panels rated like this be better for a 3 panel setup??

Voltage Maximum Power 37.20
Current Maximum Power 5.11

I can't step to a 60 MPPT (due to $$) so anyone that can help would be good....

Cariboocoot

Re: Which inverter for 12V??

Photowhit wrote: »

Dang the math thing...

MPPT charge controllers are based on Amperage out put, 630/12=52.5Amps, very likely you'll never see that, but if you fry it's on you.

Another nice thing about higher voltage systems 630 /24 = 26.25, the trick here is that I don't think the TS 45 can handle a string of 3 of this panels with a VOC of 45, so 4 panels for a 24 volt system or move up to a MS 60 for a 12 volt system...

Yes; 45 * 3 = 135 Voc which comes close to the Tristar's 150 input limit. A little bit of cold weather and you're at or over the limit. Controller shuts down. This is the same with either the TS 45 or TS 60.

ywhic

Re: Which inverter for 12V??

After checking the numbers I found these 250 watt for $300 each..

Voltage Maximum Power 30.20
Current Maximum Power 8.31
Voltage Open Circuit 37.7
Current Short Circuit 8.90

Numbers crunched would let me run 2 of these.. VOC would be 75.4 and Amps maxed would be 17.8 @ 24v or 35.6 amp @ 12v.

Converts to 199.4/panel (24v*8.31) x 2 = 398.88 x 5 hours = 1994.4 watts per day MAX..

Gives me more then 4 of the 140v 12v panels.. and is still less $$

Cariboocoot

Re: Which inverter for 12V??

ywhic wrote: »

The 210 w 24v panels are 30v and 7.11 Amp maximum numbers.. 3 would be 21.33 amps @ 24 v.. which if *2 would be 42.66 amps @ 12v unless I figured the numbers wrong..

Would 24v 190w panels rated like this be better for a 3 panel setup??

Voltage Maximum Power 37.20
Current Maximum Power 5.11

I can't step to a 60 MPPT (due to $$) so anyone that can help would be good....

With the MPPT controller the panel Amps aren't really important. The output current is governed pretty much by array Watts / system Voltage. 630 / 12 = 52.5. Since the panels rarely will hit the nameplate rating of 630 Watts it is unlikely you'll ever see that much current. 40 Amps is more likely to be the maximum current you'll ever see. Any current above the controller's max will just be "clipped". BTW, the current from the three in series will still be 7.11, not three times that; the Voltage goes up, the current stays the same. Advantageous for long wire runs.

The main problem is having the Voc of the array exceed the maximum input Voltage. Voc is always higher than Vmp. On those panels the Voc is probably around 37? If so, three in series would work.

The panels with the 37.2 Vmp would not work three in series as they are the ones likely to have the Voc around 45.

Yes, it's confusing stuff.

Cariboocoot

Re: Which inverter for 12V??

ywhic wrote: »

After checking the numbers I found these 250 watt for $300 each..

Voltage Maximum Power 30.20
Current Maximum Power 8.31
Voltage Open Circuit 37.7
Current Short Circuit 8.90

Numbers crunched would let me run 2 of these.. VOC would be 75.4 and Amps maxed would be 17.8 @ 24v or 35.6 amp @ 12v.

Converts to 199.4/panel (24v*8.31) x 2 = 398.88 x 5 hours = 1994.4 watts per day MAX..

Gives me more then 4 of the 140v 12v panels.. and is still less $$

Okay two of those would be 500 Watts. At 12 Volts that would be 42 Amps peak, although 32 Amps is more likely.
Daily "harvest" from 500 Watts is possibly 1 kW hour AC (Watts * hours of good sun * 0.52 system efficiency).

I think the three 210 Watt panels is a better choice; 40 Amps peak charge current to a 440 Amp hour battery bank is a 9% rate, and the harvest potential is about 1300 Watt hours AC.

Photowhit

Re: Which inverter for 12V??

ywhic wrote: »

Voltage Maximum Power 37.20
Current Maximum Power 5.11

The good and the bad...

The good news is these appear to be 'true' 24 volt panels, panels made to charge a 24 volt system. You could use your original charge controller and likely not loose more than 10% comared to MPPT charge controllers in the summer time panels hot voltage lower). But likely the VOC is even higher for MPPT charge controllers.

I don't know your cost/budget, but you could run 4 of these with the original CC.

Cariboocoot

Re: Which inverter for 12V??

No, I don't think he could on a 45 Amp Tristar.

Four 190 Watt panels would be 760 Watts. Derate to 77% you get 585. Divide by 12 you get 48 Amps which means it would be clipping 3 Amps any time power reached maximum.

But for the record, you would wire two in series and then parallel the two strings. Voc would be around 90, Vmp 74.4, Imp 10.22 for the array.

firerescue712

Re: Which inverter for 12V??

There is a new Rogue in the works. It is said to be 150v and 90 amps. It should be out later this year. I am using 24v panels to charge a 24v system through the Rogue without any problems. I am using Concorde AGM's. You can find good deals online on 24v panels.

ywhic

Re: Which inverter for 12V??

Cariboocoot wrote: »

I think the three 210 Watt panels is a better choice; 40 Amps peak charge current to a 440 Amp hour battery bank is a 9% rate, and the harvest potential is about 1300 Watt hours AC.

or

No, I don't think he could on a 45 Amp Tristar.

Four 190 Watt panels would be 760 Watts. Derate to 77% you get 585. Divide by 12 you get 48 Amps which means it would be clipping 3 Amps any time power reached maximum.

But for the record, you would wire two in series and then parallel the two strings. Voc would be around 90, Vmp 74.4, Imp 10.22 for the array.

So you think 3 of the 210 watts or 4 of the 190 watts will work (on paper).. and the over 45 amps are clipped and won't shut it down??

And on the 4 190w panels I'd series 2 'pairs' together..

Could I do 2 of the 210 watt panels and 1 of the 190 watts into a combiner box and be 'safe' for the MPPT 45??

Again the numbers for the 210 w panels

Voltage Maximum Power 30.20
Current Maximum Power 8.31
Voltage Open Circuit 37.7
Current Short Circuit 8.90

and the 190 w panel.

Nominal 24 V DC power output
Voltage Maximum Power 37.20
Current Maximum Power 5.11
Voltage Open Circuit 44.85
Current Short Circuit 5.80

Would work to 610/ 521.52 watts.. (24v * rated current maximum amps output).. works to 2607.6 watts for 5 hours.. OVC is 120.25 if I figured it right.. it seems like the numbers would work..

Cariboocoot

Re: Which inverter for 12V??

The two different panels (210 & 190) aren't compatible. There's a 7 Volt difference in Vmp so they won't work well in parallel. here's a 3.2 Amp difference in Imp so they won't work well in series either. These difference equate to power loss, and you probably don't want more than 5%. The Imp would be limited by the lowest number, so in effect your "big" panels would drop to 5.11 * 30.2 = 154 Watts (roughly speaking). So no advantage there.

Better to clip 3 Watts on sunny days and have that little bit extra when it's not so sunny.

Photowhit

Re: Which inverter for 12V??

Cariboocoot wrote: »

No, I don't think he could on a 45 Amp Tristar.

Four 190 Watt panels would be 760 Watts. Derate to 77% you get 585. Divide by 12 you get 48 Amps which means it would be clipping 3 Amps any time power reached maximum.

But for the record, you would wire two in series and then parallel the two strings. Voc would be around 90, Vmp 74.4, Imp 10.22 for the array.

??????

in a 12 volt system, you would just loose the over voltage so long as the CC can handle it, so it would work in a 12 volt setup, at 50% lose....

...but I was refering to a 24 volt setup, hence the 10% lose in the heat of summer when his peak use will be. might well give him the highest usable wattage for the dollar, since his heavy draw would be in the summer.

This is the reason I have most of my array hooked up this way, as my heavy draw is in the summer, when MPPT charge controllers are less effective.

Cariboocoot

Re: Which inverter for 12V??

Photowhit wrote: »

??????

in a 12 volt system, you would just loose the over voltage so long as the CC can handle it, so it would work in a 12 volt setup, at 50% lose....

...but I was refering to a 24 volt setup, hence the 10% lose in the heat of summer when his peak use will be. might well give him the highest usable wattage for the dollar, since his heavy draw would be in the summer.

This is the reason I have most of my array hooked up this way, as my heavy draw is in the summer, when MPPT charge controllers are less effective.

Voc affects MPPT controllers on start-up. System Voltage & load doesn't enter into it. light strikes panels, Voc comes up, controller tries to start, input Voltage is too high, controller shuts down.

Most PWM controllers don't have this problem of course.

Maybe we're talking at cross-purposes regarding which controller.

Photowhit

Re: Which inverter for 12V??

Photowhit wrote: »

...The good news is these appear to be 'true' 24 volt panels, panels made to charge a 24 volt system. You could use your original charge controller and likely not loose more than 10% comared to MPPT charge controllers in the summer time panels hot voltage lower). But likely the VOC is even higher for MPPT charge controllers.

I don't know your cost/budget, but you could run 4 of these with the original CC.

Coot I think you missed this...

Originally we were talking about a PWM controler, I'm saying at @$1 a watt 4 - 190watt panels in a 24volt system teamed with a PWM CC would give him the greatest usable wattage per dollar in the summer when he needs it. $1000 all in for 760 watt array and CC.

Cariboocoot

Re: Which inverter for 12V??

Photowhit wrote: »

Coot I think you missed this...

Originally we were talking about a PWM controler, I'm saying at @$1 a watt 4 - 190watt panels in a 24volt system teamed with a PWM CC would give him the greatest usable wattage per dollar in the summer when he needs it. $1000 all in for 760 watt array and CC.

That would explain it. I thought we had abandoned the PWM controller in favour of the 45 Amp MPPT and that was now the "original" controller because the 60 Amp version also was brought up.

As it is, the 190 Watts on a PWM would lose quite a bit based on the Vmp difference to a 12 Volt system: about 20 Volts (17.5 vs. 37.2) * 5 Amps or about 100 Watts. That's more than 50%, isn't it? The Summer heat loss isn't going to be that severe, is it?

Or am I confused again? Maybe I don't take enough naps. That's probably it. :roll:

Photowhit

Re: Which inverter for 12V??

Take a nap...

24V system, this guy is trying to run an AC, while not very practical, I'd like to give him a shot, The cost of an MPPT charge controller makes it impractical when his goal is to run an AC in Summer, (unless he is running panels that have no other practical way of doing the job)

I live in a hot summer climate and have run an AC off a small system, not sure anyone else here can speak to this as well as myself.

I may well ignore a 12V system as being impractical for this use, looked long and hard at it.

If I say compared to an MPPT, what should you think I'm comparing...

If I say "...in a 24volt system teamed ...." I mean a 24 Volt system and assume your either really tired or it's a full moon and the crazies are out....

I know I've had a long day, but if I was spending the money, and wanted AC, which is the exact situation I was in 5 years ago...

I'd have a 24 volt system, minimum, I'd shoot for 1000 watt array (minimum for me) and the cheapest way to get usable watts, Cheap and more panels, made to charge 24 V (I went with 12V nominal cheapest at the time, 2 in series) with a PWM charge controller, since there would be more delievered wattage than if I went with less panels and a MPPT charge controller. Please note that this is particularly true in a very hot climate.

FWIW, I've added 700 watts and replaced the 4 golf cart batteries with a huge traction battery, but the system will keep me cool tonight...

I spent a summer on the original system, and it worked out OK, the added panels gave me a bit more run time during the day after achieving float. If he does a small well insulated room he may well be able to run the AC for 2-3 hours a night with out the system collapse, My batteries made it through 4 seasons like this and 1 before that running fans only. Hard to imagine being more sucsessful.

ywhic

Re: Which inverter for 12V??

Lets try this way..

What Amperage do I need for a 24v panel and at what true Voltage?? 29, 30, 31??

Heres an ET Solar Panel 185 Watt

Nominal 24 V DC power output
Voltage Maximum Power 36.9
Current Maximum Power 5.02
Voltage Open Circuit 44.75
Current Short Circuit 5.54

I came up with 120.48 watts based on 24v x 5.02 amps.. and I know the VOC and CSC plays into this.. 44.75 and 11.08 each..

How many of those can I safely get onto a Morningstar 45 TS-MPPT controller?? I think 3..

Heres the ETSolar 190 watt I used earlier.. and Cariboo.. said 4 in parallel then series the 2x parallels..

Voltage Maximum Power 37.20
Current Maximum Power 5.11
Voltage Open Circuit 44.85
Current Short Circuit 5.80

The VOC is high on both of them..

The SunTech 210 Watt Poly (from earlier)

VPM: 30
CPM: 7.11
VOC: 36.5
CSC: 7.68

Then the 250 watt Hyundai Mono Panel..

Voltage at Pmax (Vmpp) 30.5
Current at Pmax (Impp) 8.2
Open circuit voltage (Voc) 37.5
Short circuit current (Isc) 8.7

Keep in mind this is a YEARROUND usage.. and some temps will hit 0' F.. though I doubt much/any snow in south TX..

If you had to pick which panel would you go with for the 45 MPPT and how would you wire them..

And if at 0' will I still get power from them with daylight/sun?? I have $250-300 per panel to spend @ max..

ywhic

Re: Which inverter for 12V??

Then I found things in the 210-240 range in 24v seem to work in 3 panel setups.. and comes up just about 45 amps if needed and wired in parallel and *2 for the 12v out..

Most have numbers like this Canadian Solar 230 watt panel..

Voltage Maximum Power 29.6
Current Maximum Power 7.78
Voltage Open Circuit 36.8
Current Short Circuit 8.34

This for 3 panels would (I think) be 23.34 amps in 24v and 46.68 in 12v if I did a combiner box for all 3 together.. correct??
And the VOC is 36.8 * 3 panels.. 110.4 VOC total..

I'd prefer to keep them in parallel and use a combiner.. even though I now understand I can wire all 3 in series and still have the 7.78 Amperage.. (correct?)

186.72w/panel * 3 panels = 560.16 watts * 5 hours = 2800 watts.. (if everything was golden)..

Am I learning and getting closer???

Photowhit

Re: Which inverter for 12V??

VMP on a 'true' 24 volt panel should be 34-38(VMP) volts.

You need 30.5-31.5 volts to the batteries to equalize. As panels get hot their voltage goes down, in Texas I suspect you'll see lots of this, hence the effective wattage of the panels is reduced in heat, lower voltage same current/amperage (The reason MPPT CC are less effective in hot weather)

Generally speaking in summer charging a 12 or 24 volt nominal system with a panel designed to charge a 12 or 24 volt system, there is only a 10% adavntage to an MPPT charge controller when compared to a PWM charge controller. In winter you might see closer to a 30% adavntage. So spending such a large amount of your budget on a MPPT charge controller, when you could have more panels seems impractical to me.

If your goal is to run an AC in the summer, and that will be your heaviest use... you have my recomendation.

I'll step out unless asked directly, Been there and done that REALLY! Good Luck...

Cariboocoot

Re: Which inverter for 12V??

Let's get a few things ironed out.

1). Are we talking about a 12 Volt system or a 24 Volt system?

2). With a PWM controller what goes in is what goes out. If you use a panel with a high Vmp, much of the power will be lost as the battery will pull the Voltage down. The over-all power loss is basically the panel Vmp - roughly 17.5 * the panel Amps. The current from a PWM controller will only be the panel Imp * how many panels are in parallel; current will not go up with series connections.

3). With an MPPT controller, the array Vmp has to be at or above the "ideal" Vmp for the system Voltage (12 Volt = 17.7, 24 Volt = 35) and the array Voc with any cold temp change must not exceed the controller's maximum input Voltage. The peak current will be basically the derated total array Watts divided by system Voltage.

I quite agree with Photowhit about trying to run A/C off a 12 Volt system, for all the reasons I know we have discussed before.

Before you can pick panels & controller you must finalize the system Voltage, otherwise I for one will get lost in all the panel & controller choices and not be able to give any useful advice.