Can I use a 12v inverter with a 24v setup?

System

It looks like bigger panels - 160w/24v offer simpler installation, are cheaper, and are more suited to longer cable runs, so that's what I'm looking at, along with an accompanying 24v charge controller. Specifically I've found a BP 160B PV panel and a SunSaver controller to be the cheapest combo. The thing is, there are a lot of really cheap 12v inverters that are around 1000w, but 24v inverters all seem to come from companies that are a lot more expensive. Specifically I was looking at a Chicago Electric Power inverter that is 1200w for about $100.
So - can I run a 12v inverter off of just one 12v battery in say a group of 4 12v deep cycles?

System2

Re: Can I use a 12v inverter with a 24v setup?

thats a good question, i assume you mean the batts would be wired up for 24v as one large battery.
my guess is youd put strain on that one battery, especially such a large load if you were pulling 1000w, that couldnt be good. i dont really know about this though, someone else will answer for sure.

but 2 things i know you could do are:
just buy a 24v to 12v to converter so you can use that 12v inverter, OR upgrade to a charge controller that does mppt so you could keep the batts at 12v config and use the panels in a 24v config.

BB.

Re: Can I use a 12v inverter with a 24v setup?

A few issues (assuming I understand your setup)...

The "24 volt" panels, they will need to output 30-34 VDC to charge a 24 VDC bank (need about 31 VDC to equalize, plus ~2 VDC drop for the converter--AGM's don't need equalization, so it will work with slightly less voltage). If you put several panels in series (say 64 VDC), then you can use a MPPT controller to drop the power down to what you will need.

If you have a 24 VDC bank and want to put a 12 VDC inverter on one of the series connected batteries--don't do it. The one battery will be discharged but when you go to recharge the 2x 12VDC batteries, one will still be full, the other empty, and when you recharge, you will be "equalizing" the heck out of the full battery (basically, overheating and boiling the electrolite away).

-Bill

niel

Re: Can I use a 12v inverter with a 24v setup?

the best option would be a controller with downconverting ability and it will be an mppt controller. you would sink a fortune into a 12v converter to allow that much power at 12v. if this is still too expensive for you you will have to get 12v pvs to go into the sunsaver and a 12v battery bank.
matt is right that a large imbalance would occur and it would ultimately destroy the batteries in no time so do not tap 12v from larger voltage banks of batteries.

crewzer

Re: Can I use a 12v inverter with a 24v setup?

Specifically I was looking at a Chicago Electric Power inverter that is 1200w for about $100.

For this amount of money, this is likely to be a low quality modified sine wave (MSW) inverter. Problems you're likely to encounter include:

1) AC loads typically run hotter when powered from an MSW inverter. This may lead to early load failure, such as a burned up motor.
2) The extra energy consumed in (1) above actually reduces effective inverter efficiency, so the battery drains faster.
3) The 1,200 W rating is probably not a continuous rating, even if it claims to be.
4) The inverter and/or your loads will likely fail at some not-to-distant point, and these items will need to be replaced.
5) The inverter should be OK for experimenting with simple, light and inexpensive loads.

HTH,
Jim / crewzer

System2

Re: Can I use a 12v inverter with a 24v setup?

Alright, thanks. Anyone have recommendations as far a the cheapest mppt controller for this application?

niel

Re: Can I use a 12v inverter with a 24v setup?

as to the cheapest mppt controller you can look for yourself.
http://store.solar-electric.com/chco.html
this is only one place of looking so it's up to you to research. btw we highly recommend that no matter what controller you get it should have a remote battery temperature sensor capability and please use it.

crewzer

Re: Can I use a 12v inverter with a 24v setup?

Careful... the "cheapest MPPT controller for this application" will mean one that can charge a 12 V battery from a nominal 24 V PV array. You're probably looking at the Blue Sky 3024. The SB2000 and the 2512 can't reliably handle 24 V PV modules.

Or, you can stay with the 24 V controller, skip the $100 MSW inverter, and put that money plus the cost of the 3024 towards a quality true sine wave inverter like the Exeltech XP250.

HTH,
Jim / crewzer

System2

Re: Can I use a 12v inverter with a 24v setup?

i wonder what since wave inverters have the best warranty? i think my next purchase is a true sine wave in the 1000w to 1500w range and noticed samlex has best prices,and 1 yr warr. according to the hosts webstore that is, exceltech of course good brand , a little more $, but far cheaper than the prosines..

i would like to get a nice high rated one so that we can start doing the vacuming on sunny days
could also use it as backup for the pellet stove

oops do they call this thread hijacking? well, to the OP -i would highly recommend a investment ina pure sine wave inverter too. this way you can run anything (up to to the rated wattage o course). i have bought a couple modified sine wave el cheapos (thats cheap in spanish) and completely wish id just saved for a pure save wav!

System2

Re: Can I use a 12v inverter with a 24v setup?

Well I consider my el cheapos MSW inverters as money well spent from the point of view that they taught me just what is possible with my solar system. It can do far more than I had ever thought.
Now I know it's worth spending money for a "real" inverter. Just have to come up with that money. LOL
Wayne

System2

Re: Can I use a 12v inverter with a 24v setup?

yes, certainly not worthless. i have 12v run out to my office and have the plug split into a 3 cig lighter config: one is a 300w modsine iverter for my camera and cell phone charging, the other is a 12v standard battery charger, the other 12v plug is for running the pc. this all works great at max efficiencies except for the small load ac recharging, but still i want to look closely at the efficiencies of a pure sine wave inverter that doesnt use too much power when not in use, something thats switchable maybe (the idea of even a few watts running while something idles just kills me!) ..then i can convert the (undersized at 12v) runs i already have to be my separate offgrid ac jacks.

System2

Re: Can I use a 12v inverter with a 24v setup?

The best lessons are usually the most expensive. I too was running a cheap Chicago electric inverter off my 12v bank. The cost was just too inviting for a noob. Mine was the 2000w mod sine wave and it worked actually pretty well for about 9 months or so, then whamo. The inverter's low voltage alarm kept sounding, and the bats had a good voltage reading. Switched to a smaller Xantrex inverter and all is well. My small 210ah bank will run my Big screen for a couple of hours and even a dorm size fridge for half a day. Fun little project for about $1000 invested. :-D

mike95490

Re: Can I use a 12v inverter with a 24v setup?

shawndecker1 wrote:

The best lessons are usually the most expensive. I too was running a cheap Chicago electric inverter off my 12v bank. The cost was just too inviting for a noob. Mine was the 2000w mod sine wave and it worked actually pretty well for about 9 months or so, then whamo.

And ????? You said "most expensive" and "whamo"

Where's the Kaboom !! I'm waiting for the horror story about the inverter frying your big screen TV, or shorting out the battery bank, leaving you with a room full of copper /lead plasma and acid on the floor.

System2

Re: Can I use a 12v inverter with a 24v setup?

Luckily, no. My inexperience and experimentation has only cost me the replacement of my inverter, which still works, just not something I want to power anything expensive. I use it now only in automotive applications as it was designed. My Xantrex meter is my "brain" and I trust it. I just don't want anyone thinking that the cheapest road is the best road, especially in solar. The "whamo" was the inverter's incompatibility to this application, something I wouldn't do again. Hey I'm honest, I jumped into solar very green and eager. (Like most). :-D It's an education in alternative energy that didn't cost me a college degree, only a few weekends doing something positive. I enjoy it and will continue making mistakes. My avatar says it all. :-)

kc8adu

Re: Can I use a 12v inverter with a 24v setup?

And ????? You said "most expensive" and "whamo"

Where's the Kaboom !! I'm waiting for the horror story about the inverter frying your big screen TV, or shorting out the battery bank, leaving you with a room full of copper /lead plasma and acid on the floor.

thats what fuses/breakers are for!