24v or 12v inverter & bank??

ywhic

I have not bought any inverter yet or batteries..

I have 5 panels (12v (18VDC) rated) at 145w each.

My Morningstar TS-45 (PWM) is rated at 45 amps.. so these 5 panel in parallel total 40.x amps at optimum.. all is well if I go with 12v battery bank and a 12v 2000w inverter..

I can step to 870 watts with 6 panels (just buy 1 more later this month of same 145).. and then run a 24v system.
(use 3 parallel strings of 2 panels each to get the 24v). The controller would be fine for that and more..

Now I plan on running an Air Conditioner (550 watt AC rated) for 1-2 hours and have say a 330-440ah battery bank at 12v.

IF I were to go with a 440ah 24v battery bank.. and a 24v 2000w inverter:

Does the 24v inverter draw less current and amps from the 24v battery bank per hour of use??

at 12v I'd be drawing (lets say estimated) 50 AH of use..

at 24v,what would I'd be drawing from the 24v bank?? Would it be half??

I know the wiring would be lighter than the 3/0 I have.. and I would need less AMPs on the inverter fusing..

So does a 24V inverter DRAW less overall??

And if yes, can I run the same Air Conditioner for 3-4 hours vs. the 1-2 on a 12v system.??

PS. Happy Fathers Day to fellow Dads..

Cariboocoot

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

Sorry Al, but the answer is; it depends.

You need to look at the particular inverters involved.
Exeltech XP2000 is available as 12 or 24 Volt. Both models are listed as drawing 12 Watts (no load).
Samlex SA-2000K is available as 12 or 24 Volt. The 12 Volt version lists the no load current as 2.8 Amps (33.6 Watts) and the 24 Volt version is 1.5 Amps (36 Watts). (Pretty horrible compared to the other.) The 12 V is 89% efficient, the 24 V 92%.
The Outback FX2012 and FX2524 both draw 20 Watts full-on, 6 Watts in search mode.

So you have to check the specs carefully on any inverter you're considering. The main advantage to 24 or 12 is the lower current for any draw and typically about 1% greater efficiency in conversion.

westbranch

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

Al, the answer to your 'draw' question is dependent on which inverters you are comparing. Each inverter is (probably) different as it may have a different PFC and idle draw as well as sleep mode (if it has that option).

you have to choose which ones to compare first. any answer now would be conjecture.

HTH

waynefromnscanada

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

ywhic, you most definitely did the right thing by asking before you purchase. Others will chime in I'm sure, (already have because they type faster than I do ) but the loads you're looking at are large for an off grid system. Do NOT go with 12 volts, the huge currents required will require huge cables and will be difficult to handle/control. Go for at least 24 volts, that will cut the currents in half and make a better overall system of this size.
Watts is amps X volts. So 550 watts to run the AC, + general losses = 600 watts. So if you run the AC 2 hours, you'll be using roughly 600 watts X 2 hours + 1200 watt hours. Or 1.2 kwh hrs.
On 12 volts, that would be 1200/12 = 100 Amp Hrs taken from you're batteries.
On 24 volts, it would be 1200/24 = 50 AH from your 24 volt battery bank.
In both cases, it would be taking 1.2 kwh Hr from you're batteries. The difference would be the much smaller currents (amps) that have to be handled.
Now consider this: That 1.2 kwh PLUS any other power you use per 24 hour period, must be able to be replaced by panels in the average 4 hours of sunshine you might get the next day. And don't forget all the extra system losses. Now, what else will you be running? Water pump? Fridge? Freezer? Desk top computer 24/7? Lights? All these things will be added to the 1.2 kwh Hr just to run the AC.

ywhic

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

@Cariboocoot.. Yes I would going more than likely with the Samlex/Cotek 24V inverter..

@wayne.. I figured my othe numbers in.. 2- 13W CFL's.. a Shurflo 110V 2.8GPH pump (0.9 amp max draw on a pressure switch and a wall switch).. My latop is 17 watts draw.. (just got my Killwatt meter). The fridge will be a HIGH EER one of 4-7 cu ft.. under 1KW per day..

The good news is I still have my 3/0 wire for the inverter so losses should be NILL with a 24v setup.. (I was setting up for 12v system)..

I think the 870w (24v) array would make the numbers I need going into a decent sized battery bank.. the Air Conditioner would only be run during peak sun isolation hours and not at night.. I'd still like to bank some juice back into the batteries..

westbranch

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

FYI compare the idle draw of the 1500W to 2000W inverters in their ST family. the 1500 has 50% less draw that the 2000

ywhic

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

westbranch wrote: »

FYI compare the idle draw of the 1500W to 2000W inverters in their ST family. the 1500 has 50% less draw that the 2000

Do you think a 1500 will kick over a 5-6K BTU Air Conditioner?? I'd be happy with a 1500w (along with the lower cost)... :cool:

westbranch

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

I'm not familiar with A/C units, ours is a fan.

Just looked at the manual and the 1500 has a 3 min output of 1750W with a 3000w surge.

ywhic

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

westbranch wrote: »

I'm not familiar with A/C units, ours is a fan.

Just looked at the manual and the 1500 has a 3 min output of 1750W with a 3000w surge.

What 1500 w inverter you have?? Samlex/Cotek?? or ??

I've been figuring I would be at 3* the rated power for the surge.. (after a month of reading on the 'net' about Air Conditioners and Solar).. so 1500 more than likely WOUD work.. but no one has done a test for a 1500 w inverter and a 5-6K air unit..

Photowhit

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

ywhic wrote: »

...so 1500 more than likely WOUD work.. but no one has done a test for a 1500 w inverter and a 5-6K air unit..

Splash, splash,spl...

I did say I ran off a 1400watt for a couple summers, but this will vary depending on AirC and inverter.

Cariboocoot

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

The stand-alone Samlex units have a very poor surge rating: double the output but for less than 1 second. Not a good choice for starting AC induction motors. The surge for an A/C that runs 500 Watts is likely to be >1500 Watts and may last longer than 2 seconds.

I've got some of the A/C units in storage. I'll try to dig one out this week and run it through the meter and see what I get. Probably a hernia from lifting the thing.

westbranch

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

which Inverter do I have? see my sig line, it is an ST 1500W (Cotek). It is a hard wire model with transfer switch.

I saw in one of the Samlex manuals (PST 30S 12A 24v) that they list an air compressor unit will draw 4 X the power on start up, an A/C would be at least that, both are compressors of a sort...

*NOTE:The surge power rating specified for this inverter is valid for duration
of less than 1 second. This very short duration may not be sufficient to
start motor based loads which may require up to 5 seconds to complete
starting process. Hence, for purposes of sizing the inverter, use only the
continuous power rating of this inverter.
Type of Device or Appliance Surge Factor for Determining the Continuous *Wattage of the Inverter
(No. of times the running power rating of the device/appliance)
Refrigerator / Freezer5
Air Compressors4
Dishwasher3
Automatic Washer3
Sump pump3
Furnace fans3
Industrial motors3
Portable kerosene / diesel fuel heater2
Circular saw3
Bench Grinder 3

HTH

mike95490

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

ywhic wrote: »

What 1500 w inverter you have?? Samlex/Cotek?? or ??

I've been figuring I would be at 3* the rated power for the surge.. (after a month of reading on the 'net' about Air Conditioners and Solar).. so 1500 more than likely WOUD work.. but no one has done a test for a 1500 w inverter and a 5-6K air unit..

Most motors need 5 - 10 x running amps, to start.

ywhic

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

Stuck in a lurch..

PST-200S-24A is like $650 but has an 85% eff rating and <0.8 A no load draw

The SA-2000K-24 is $770 but has a 92% eff rating and a 1.5 A no load draw with powersaver OFF.. with it on its 0.3 A no load..

Most Samlex 1500 watt 24v's are less than $500.. but the eff numbers are 85-87%.. though the no load is less than <1.0 A

The downside is also Samlex have the PIN terminals.. and I have 3/0 wire I'd rather not waste.. it says upto 1/0 will fit the PIN's they supply.. I dunno..

This is why the 12V Xantrex Pro SW2000 for like $350 keeps calling me back.. its also got an 90% eff and no load of <0.8 A.. and has 3/8" terminals hanging on it for lugs..

Cariboocoot

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

I think the Xantrex SW series have been discontinued, so any of those for sale would be leftover stock. This is not necessarily an issue, but it should be mentioned. It seems Schneider is moving the product line away from the small-scale install (like RV's and cabins) and more towards whole-house GT back-up systems.

Al, you're up against the hard and fast rule "you get what you pay for". You can't have the power and efficiency you want without shelling out the spondoolicks. Brand 'X' used to make a 24 Volt 1800 Watt Prosine: http://www.xantrex.com/power-products/power-inverters/prosine.aspx Maybe you can find one somewhere?

Photowhit

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

I think the 'SW' line that has been discontinued(for some time now) is from the original 'Trace' line of products, There is a current SW series in the Prowatt line of products.

I have and recomend the Prosine 1800 watt version, but if you need an inverter charger, for 24 volt, you need to look for the 2000 watt prosine. This will be a consideration when going to a 24 volt system.

Coot, your post looks like they are discontinuing the Prosine and Prowatt lines? isn't that link to their current lines?

Cariboocoot

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

Good question, Photowhit.
NAWS's Xantrex page says "The Xantrex SW, SW-Plus, and DR inverters have been discontinued. The SW/SW+ line has been replaced with the new Xantrex XW inverters. The DR series has been replaced with the new TR (Trace) inverters."

Brand 'X' has me completely confused on this (not hard to do).

Photowhit

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

I think those are all the old standards, white with green line square box stuff. I thin Prowatt and Prosine were independent companies bought by Trace/Xantrex. I'm no authority, just old...

ywhic

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

Well that may totally stink then.. I thought the Xantrex ProWatt SW line just came out in 2010??

Theres an old post from 2007 from NAWS saying the same thing.. this is confusing..

http://forum.solar-electric.com/showthread.php?644-Xantrex-Discontinuing-DR-and-SW-Lines

I guess I'll have to wait and see.. I may get stuck with Samlex..

ETA.. the Cotek SK-2000 model looks pretty good for $700 flat..

Dill

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

Al, take it from someone who initially went 12V...you want a 24V system. Once I get done with my cabin, I will be buying a 24V inverter and converting my home install over.

Photowhit

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

FSU wins and advances....

Central Missouri gets rain, 1st time in almost 4 weeks...

and Photowhit tries to be polite and doesn't say "Coot your wrong" and gets ignored by the original poster, who just keeps splashing around...

raydias

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

If you only plan in running the air conditioner for a specific time then turn it off why not turn off the inverter as well. That way you don't need to worry about no load draw.

ywhic

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

Photowhit wrote: »

FSU wins and advances....

Central Missouri gets rain, 1st time in almost 4 weeks...

and Photowhit tries to be polite and doesn't say "Coot your wrong" and gets ignored by the original poster, who just keeps splashing around...

Sorry caught up in the moment..

I remember the conversation.. but once I shell out for a 1500 w over a 2000 w in whatever flavor/brand I need to be 100% certain it will kick a 5-6K BTU A/C on.. maybe Cariboocoot will post results if he has time to test an A/C on his 1500w inverter..

If I go with a 2500/5000 Stackable MSW like you said last month.. did you have issues with lights flickering and such??

@ Dill.. I hear you.. the only issue I have again is timing.. I got to get my driver side car window back on track for $130 (its been broken since last September).. and that leaves me short for the #6 panel to go 24V... and gosh only knows if DM will get another container in with this tarriff mess going on.. maybe this container will be late and I will have another check in hand by then..

Inverters in Samlex/Cotek are almost the same $ for 12/24V..

@ Ray.. I would but I want only 1 inverter for the whole thing.. not 2.. I could go with a 1000w good sine model and a 2000w MSW model for just the A/C..

maybe a 2-3K TrippLite MSW.. but I never saw the followup pics from that other thread..

ywhic

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

westbranch wrote: »

I'm not familiar with A/C units, ours is a fan.

Just looked at the manual and the 1500 has a 3 min output of 1750W with a 3000w surge.

Found the Cotek ST-1500 for like $650.. with 1750 3 minute surge this may work.. and its hardwire and has a transfer switch built-in..

Any suggestions for an PURE SINE inverter that will work under $650..???

westbranch

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

the ST series is TSW...

waynefromnscanada

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

Such a shame that Xantrex discontinued the Prosine 1800. It would start that AC no problems whatever. I've done it.
It was and is one awesome inverter, all kinds of surge to start motors etc.
Just can't understand how any sane company could just up and walk away from such a winner

ywhic

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

Anyone run the Magnum MSW inverters with good long term success??

Cariboocoot

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

ywhic wrote: »

Anyone run the Magnum MSW inverters with good long term success??

You mean the ones that cost $1200+/-? Or double what you want to spend?
Perfectly good inverters. "Cleaner" than many other MSW inverters (60 Hz +/- 0.005% according to specs). Really good surge rating (the 1824 good for 2400 Watts for 30 minutes, 3300 Watts for 30 seconds). Built-in PF corrected charger. But it's a lot more money (unless you find a used one) than the Samlex/Cotek or Exeltech for that matter.

ywhic

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

I was wondering about the Magnum MM1524AE MSW (24v).. 1500 continuous.. 91% eff.. and a 20 Amp Transfer Switch builtin.. & 35 amp charger..

Its got some nice specs (IMHO) on the 24v version.. and its like $750 shipped..says a 9 watt NO LOAD draw..

Output frequency and accuracy: 60 Hz ± 0.005%

5 sec surge power (real watts) 2650
10 sec surge power (real watts) 2575
30 sec surge power (real watts) 2500
5 min surge power (real watts) 2350
30 min surge power (real watts) 1900

Photowhit

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

waynefromnscanada wrote: »

Such a shame that Xantrex discontinued the Prosine 1800. It would start that AC no problems whatever. I've done it.
It was and is one awesome inverter, all kinds of surge to start motors etc.
Just can't understand how any sane company could just up and walk away from such a winner

????????What makes you think it has been discontinued???????

The link to the product on Xantrex's web site?http://www.xantrex.com/power-products/power-inverters/prosine.aspx

Her is a link to discontinued products from Xantrex's web site. I don't see prosine on it anywhere.

Here's a list of current product line, You can follow the path to Prosine.

Lets NOT start rumors, lets show links to facts, if someone has one post it.

Cariboocoot

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

Not a bad deal at all. Check and see if that's with the remote http://www.solar-electric.com/me-rc50.html or not. NAWS is including it with all Magnum chargers right now - no extra cost.