240VAC inverter question

[suburbancowboy]

My electrician came up last week and got all the rough electrical put in the cabin.  On the out side panel he wired the system to use 240VAC.  He then wired in a 10 gauge core that we then connected to my generator. 240V output on the generator.  Inspector loved the setup and passed everything.  Now my problem, I don't want to use the generator most of the time. I built a solar trailer two years ago that outputs 110V power.  I have seen 12,24,48v DC to 240VAC inverters but they seem expensive for anything over 1000W.  $500+.  I was wondering if any of you have a suggestion as to what I should do to get my power from my solar setup vs. my generator?

I would even consider a new solar setup if I could get 200W of panels, controller and inverter < $1000.  I have checked the web but not finding much.

[hpinson]

That's probably  low from what I've seen for prices this week.  The panels can be had inexpensivly enough and there are lots of sources. You also need to factor in batteries (unless you are doing direct PV), a combiner/ breaker and copper wire, which is pricy right now.    The name brand MPPT charge controllers seems to be in the $300 - 1K range, and the PVM controllers are quite a bit less. Batteries seem to be rising in price inversly to panels, and the shipping costs are outrageous.  Good inverters are pricy as well.

There is a lot of inexpensive / unknown quality Chinese hardware on ebay right now.

I'm not sure where you are located, but if near the Southwestern US, I've had good luck with Northern Arizona Wind and Sun, and Affordable Solar in Albuquerque:

http://www.windsun.com/

http://www.affordable-solar.com/

[old_guy]

You could probably set things up to power one side of the panel from your solar.  All 110 breakers on that side would be powered.  Depending on what breakers are where, this might let you power the things you need when on solar.

I expect I will learn more about solar and wiring in a few minutes when someone with more experience reads this. 

[mgramann]

You could probably set things up to power one side of the panel from your solar.  All 110 breakers on that side would be powered.  Depending on what breakers are where, this might let you power the things you need when on solar.

I expect I will learn more about solar and wiring in a few minutes when someone with more experience reads this. 

Actually, you could power both sides of the panel, but you couldn't use 220 breakers because both sides of the panel would be in phase with one another.  Experts please correct me if I am wrong.

If you just plan to power one side of the panel, be sure to turn all of your 220 breakers off-especially if you use resistance heating like an electric water heater.  I doubt you do, since you are off grid, but you never know.  Our generator only powers one side of our panel, and power backfed through the heating element to the other side of the panel-at least I think that is what happened...Again, experts please correct me.

[UK4X4]

240-210Volt circuits instead of using neutral and live they use oposite lives / diferent phases

So you should be just be able to re-wire the panel to 110V if thats what you want to use, you may see either a 3 wire or 4 wire in

3 wire phase a neutral and phase b
he may have a seperate neutral or just used it as earth

4 wire in would be the same only 3 phases and 1 neutral- which I doubt the generator provides

Plus the earth- earth and neutral are probably linked at the box inputs

With a multimeter on the input wires connect the neg to earth and poke arround to find your 110 v phase supplies
You'll only see 210 across two lives.

SAFETY NOTE _ I usually work on the 1 hand in the box at any time method, ie if I touch live my hand jumps back out rather than across my heart to the other hand holding the box.......old school but is a life saver.

Next after that are the fully insulated screwdrivers and pliers...


Depending on how he wired the breakers you could have either 2 or three banks- each connected to 1 phase

ie he splits the loads across each phase.

If you are only using low power gear- these can be linked back together

Depending on the make and distribution box- he may have labled the phases with stickers red yellow and blue

Or the bus bars are visable - or you may need to remove the breakers to see them if they run behind.

Take your time- read a book if you have one to get the American version as remember I'm a Brit !

If it were me and I've done it before is to find some Industrial style sockets and plugs
ie Mr average does not have one arround

Wire one for your generator
wire one for your solar system

The sockets are angled- install so that you can't get both in at the same time ie they are angled towards each other
Run a seperate breaker above each one- you now have both systems and can't physically blow anything.

If you draw up the circuit you can see- we can probably help better

This sort of thing usually used in the industrial sector- I have these on my welder and have a dedicated socket too that travels with me from place to place

[NM_Shooter]

I have a couple of questions for you :

Do you have any 240V appliances that you need to run?

Can you serve your entire power load off of the capacity one phase of your generator? 

[davidj]

You definitely shouldn't power both legs with the same phase unless you've made sure there aren't any shared neutrals.  Often e.g. a 12/3 will run to a pair of outlets so there are two lives but only one neutral.  Due to the two phases being opposite of each other, the neutral carries the difference of the currents not the sum of the currents.  If you put both legs on the same phase then you get the sum of the currents on the neutral - it could be carrying twice as much as the lives and be beyond the rating of the conductor.  An example where this is common is dishwasher/disposal circuits - it looks like a regular dual outlet but each receptacle is on a different circuit.

There's also the issue of the rating of the neutral bar in the box.  In this case all you need to make sure is that the breaker on your gennie is no higher than either of the main breakers in the box.

There may be other issues to think about too, so I'd check with an electrician.  And if you do do it, put a big sign in the box saying something like "both legs on same phase" so someone doesn't do something dangerous when you're not around (and to remind yourself too).

PS I'm stuck with a 240V well pump so I didn't get to try any of this, and I'm not an electrician!

[mgramann]

You definitely shouldn't power both legs with the same phase unless you've made sure there aren't any shared neutrals.  Often e.g. a 12/3 will run to a pair of outlets so there are two lives but only one neutral.  Due to the two phases being opposite of each other, the neutral carries the difference of the currents not the sum of the currents.  If you put both legs on the same phase then you get the sum of the currents on the neutral - it could be carrying twice as much as the lives and be beyond the rating of the conductor.  An example where this is common is dishwasher/disposal circuits - it looks like a regular dual outlet but each receptacle is on a different circuit.

That seems like a potentially dangerous way to wire something.  All it takes is someone inexperienced to re-arrange the panel and end up with both sides of the wiring on one side of the panel, causing the same issue.

I'm not saying it wouldn't be up to code, I just wouldn't do it that way for the reason above.

[PorkChopsMmm]

I power both sides of my panel with 120 -- it is a 200 AMP utility panel. Works just fine.

[craig]

Without knowing exactly how your system is wired, if your existing solar/inverter system outputs 120 VAC, you could simply buy a single phase 120VAC-230 VAC transformer, sized according to your inverter size in watts and wire the 230 VAC secondary side of the transformer to your panel. When you use the generator you would need some sort of switch to remove the transformer from the circuit. These size transformers(2000-5000VA) are common and cheap.

[suburbancowboy]

Thanks for all the reply's.  I have been looking at this inverter.

http://www.amazon.com/Modified-power-inverter-converter-system/dp/B006A2KEQM?tag=isharepost-20

What do you all think?

I have seen this as being listed as a 50-60Hz.  Can this be correct?  Or is this just bad chinese junk?

Currently I am thinking this or the transformer idea mentioned above.

[suburbancowboy]

Also what kind of connector is on the back.  Never seen one like that before.

[MountainDon]

I have seen this as being listed as a 50-60Hz.  Can this be correct?  Or is this just bad chinese junk?

Yes, the frequency could be switchable.
Yes, it is Chinese junk.

IMO.

That's a strange looking receptacle.


How will the batteries be charged? If the answer to that is someplace I have forgotten.

[UK4X4]

agree on the chinese junk !

"Also what kind of connector is on the back.  Never seen one like that before"

I can see a female IEC and a universal socket, which accepts eur/UK/and american two and three pin plugs

This normally means it has crap contacts

I have a few transformers and socket bars which have them, being we travel so much i have both 220 and 110 everythings but means you have to wiggle the plugs to get a good connection

[UK4X4]

I have one of these in the UK- but biderectional 110v to 240 and 240 to 110

oil filled enclosure with a transformer- no moving parts- solid industrial quality


http://www.toolbaydirect.co.uk/catalogue/product/Transformers/249/Defender-33kVA-Dual-Outlet-110v-to-240v-Portable-Step-Up-Transformer-E203030/165160/