Off-the-grid with grid-tie inverter?

Xringer · 03-15-10, 03:43 PM

http://ecorenovator.org/forum/applia...-inverter.html

http://ecorenovator.org/forum/solar-...-inverter.html

If this configuration would actually Start up, it seems like the 12VDC-to-120VAC inverter
would be using very little from the battery, since the grid-tie inverter
would try to make it's voltage just a tad higher..

Anyways, I was thinking this might be the lowest cost way to DIY off-grid power..

If it did work, you could stack the little 300 watt grid-tie (or Enphase) GTIs
and get some nice power-point-tracking from each panel..

Comments please:

Thanks,
Rich

Daox · 03-15-10, 04:10 PM

It looks interesting. But, in order for this setup to be legal, you'd still need some sort of disconnect going to your service panel. Or, are you thinking the grid tie will take care of that?

NiHaoMike · 03-15-10, 04:24 PM

It would be cheaper to just use a regular inverter.

Xringer · 03-15-10, 04:26 PM

I'm thinking more along the lines of taking a couple of 200 watt panels camping with you,
or to some remote cabin site..

The idea here, is to use the much cheaper grid-tie micro-inverters, off-the-grid.

Or, maybe you have to do some light construction work, way out in the boondocks?
Haul out some 220 watt panels, a little power-box to hook up to your 12v truck battery,
connect up some panels and you could run small power tools and charge
up the rechargeable power tools on site. (If the sun stayed out).

Would not replace a gas generator, but might be good if you didn't need 5KW..

I'm pretty sure that PV is going to get a lot cheaper, pretty soon..

Xringer · 03-15-10, 04:31 PM

Quote:

Originally Posted by NiHaoMike

It would be cheaper to just use a regular inverter.

You can, when the clouds come in..

Of course, it would be even cheaper if you used a hand-cranked generator..

Daox · 03-15-10, 04:40 PM

If this setup is completely off grid why do you even need the grid tie inverter?

Xringer · 03-15-10, 07:39 PM

Because, they are compatible with many PV panels, cheap &,
they are scalable when used off-grid or with a grid-tie system..

Scalability is important if you only need (or can only only afford) a few hundred watts.
You can meet that need at a reasonable price with micro-inverters.

Daox · 03-16-10, 07:30 AM

I was under the impression that grid tie inverters need to be connected to the grid to work.

Xringer · 03-16-10, 08:56 AM

Leo, Do you Know what the Gird is? Do you want to know the truth?

The answer, the number 60. As in 60 Hz. The voltage is 120 or 230.

So, as I've said before, if you can trick the GTI into thinking it's
connected to the grid, then it will work..

That's why the 12Vdc-to-120Vac inverter needs to have a pretty clean output.

I'm pretty sure that my little modified-sine-wave inverter would NOT work.

But I'll bet an old UPS (computer back-up Un-interruptable Power Supply) would work just fine.

And, it has it's own LA pack!

Daox · 03-16-10, 09:30 AM

I suppose that makes some sense. It just seems a bit more complicated than it needs to be.

03-15-10, 03:43 PM	#1
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	Off-the-grid with grid-tie inverter? http://ecorenovator.org/forum/applia...-inverter.html http://ecorenovator.org/forum/solar-...-inverter.html If this configuration would actually Start up, it seems like the 12VDC-to-120VAC inverter would be using very little from the battery, since the grid-tie inverter would try to make it's voltage just a tad higher.. Anyways, I was thinking this might be the lowest cost way to DIY off-grid power.. If it did work, you could stack the little 300 watt grid-tie (or Enphase) GTIs and get some nice power-point-tracking from each panel.. Comments please: Thanks, Rich

03-15-10, 04:10 PM	#2
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	It looks interesting. But, in order for this setup to be legal, you'd still need some sort of disconnect going to your service panel. Or, are you thinking the grid tie will take care of that? __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

03-15-10, 04:24 PM	#3
NiHaoMike Supreme EcoRenovator Join Date: Oct 2008 Location: Austin, TX Posts: 1,154 Thanks: 14 Thanked 257 Times in 241 Posts	It would be cheaper to just use a regular inverter. __________________ To my surprise, shortly after Naomi Wu gave me a bit of fame for making good use of solar power, Allie Moore got really jealous of her...

03-15-10, 04:40 PM	#6
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	If this setup is completely off grid why do you even need the grid tie inverter? __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

03-16-10, 07:30 AM	#8
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	I was under the impression that grid tie inverters need to be connected to the grid to work. __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

03-15-10, 04:26 PM	#4
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	I'm thinking more along the lines of taking a couple of 200 watt panels camping with you, or to some remote cabin site.. The idea here, is to use the much cheaper grid-tie micro-inverters, off-the-grid. Or, maybe you have to do some light construction work, way out in the boondocks? Haul out some 220 watt panels, a little power-box to hook up to your 12v truck battery, connect up some panels and you could run small power tools and charge up the rechargeable power tools on site. (If the sun stayed out). Would not replace a gas generator, but might be good if you didn't need 5KW.. I'm pretty sure that PV is going to get a lot cheaper, pretty soon..

03-15-10, 07:39 PM	#7
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	Because, they are compatible with many PV panels, cheap &, they are scalable when used off-grid or with a grid-tie system.. Scalability is important if you only need (or can only only afford) a few hundred watts. You can meet that need at a reasonable price with micro-inverters.

03-16-10, 08:56 AM	#9
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	Leo, Do you Know what the Gird is? Do you want to know the truth? The answer, the number 60. As in 60 Hz. The voltage is 120 or 230. So, as I've said before, if you can trick the GTI into thinking it's connected to the grid, then it will work.. That's why the 12Vdc-to-120Vac inverter needs to have a pretty clean output. I'm pretty sure that my little modified-sine-wave inverter would NOT work. But I'll bet an old UPS (computer back-up Un-interruptable Power Supply) would work just fine. And, it has it's own LA pack!

03-16-10, 09:30 AM	#10
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	I suppose that makes some sense. It just seems a bit more complicated than it needs to be. __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.