Grid tied inverters in off grid configuration.

[SIGP2101]

OK, here is another one from total beginner. Thinking out of the box here.

Has anyone successfully utilised grid tie type of inverter in off grid application. Being hooked up directly to battery bank and run loads that way.
Reason why I am asking this is because there are so many more available to chose from in 36V DC world than in off grid 36V DC world.
Before I pull the trigger on el cheapo unit I was looking if anyone has successful experience to share. Such a case would open up whole new world of possibilities for me.
Second reason is that some of the grid tie type of inverters by default can run on a range of voltages(22 to 60V). This would also have positive impact to flexibility of my off grid system. 24-36-48 volts battery banks for example.

Thanks!

[jflorey2]

Has anyone successfully utilised grid tie inverters in off grid application.

Sure, that is quite possible with both AC coupled and hybrid systems. Not sure why you would want to do that, but it will work.

Being hooked up directly to battery bank and run loads that way.

OK that's the opposite of what you just asked.

1 Standard off grid system: solar drives charge controller which charges batteries. Batteries store energy. Inverter converts DC battery power to AC power.

2 Standard on grid system: Solar drives inverter. Inverter converts DC to AC power and puts it directly on the grid.

3 Hybrid system: solar drives charge controller which charges batteries. Batteries store energy. Inverter converts DC battery power to AC power. When connected to the grid, inverter also sends power back to the grid once the batteries are full.

4 AC coupled system: Standard on grid system: Solar drives grid tie inverter. Inverter converts DC to AC power and puts it directly on the grid. When power is out another battery backed inverter takes over and provides the 60Hz that the grid tie inverter needs.


2) is easy. 1) is a bit harder. 3) is a bit harder still. 4) is considerably harder.

Reason why I am asking this is because there are so many more available to chose from in 36V world than in off grid 36V world.

What does that have to do with grid tie inverters? What, specifically, do you want to do? And what is the "36V world?"

[SunEagle]

OK, here is another one from total beginner. Thinking out of the box here.

Has anyone successfully utilised grid tie inverters in off grid application. Being hooked up directly to battery bank and run loads that way.
Reason why I am asking this is because there are so many more available to chose from in 36V world than in off grid 36V world.
Before I pull the trigger on el cheapo unit I was looking if anyone has successful experience to share. Such a case would open up whole new world of possibilities for me.
Second reason is that grid tied inverters by default can run on a range of voltages. This would also have positive impact to flexibility of my off grid system.

Thanks!

Just about all legal grid tie inverters require the "grid" to work. And as far as I know there isn't any way to "fool" that inverter to thinking it is connected to the grid.

Now there are hybrid grid tie inverter that will also allow you to charge batteries and use that power without the grid but they are a totally different (and expensive) animal.

[SIGP2101]

Sure, that is quite possible with both AC coupled and hybrid systems. Not sure why you would want to do that, but it will work.

OK that's the opposite of what you just asked.

1 Standard off grid system: solar drives charge controller which charges batteries. Batteries store energy. Inverter converts DC battery power to AC power.

2 Standard on grid system: Solar drives inverter. Inverter converts DC to AC power and puts it directly on the grid.

3 Hybrid system: solar drives charge controller which charges batteries. Batteries store energy. Inverter converts DC battery power to AC power. When connected to the grid, inverter also sends power back to the grid once the batteries are full.

4 AC coupled system: Standard on grid system: Solar drives grid tie inverter. Inverter converts DC to AC power and puts it directly on the grid. When power is out another battery backed inverter takes over and provides the 60Hz that the grid tie inverter needs.


2) is easy. 1) is a bit harder. 3) is a bit harder still. 4) is considerably harder.


What does that have to do with grid tie inverters? What, specifically, do you want to do? And what is the "36V world?"

jflorey, I want option # 1 from your list - but I want to use grid tie inverter instead of off grid inverter since off grid type of inverter is hard to find in 36V DC in acceptable quality. Grid tie inverters are many in 36V on DC side. Option 2, 3 and 4 are out of scope since there is no grid in my system.

Do you implying in your option # 1 that is possible to use grid tied type of inverter?

Thanks!

SIGP2101

[SIGP2101]

Now there are hybrid grid tie inverter that will also allow you to charge batteries and use that power without the grid but they are a totally different (and expensive) animal.

Are you referring to grid tied inverter/chargers by any chance? I find few of these in 36V and was also wondering will they work in off grid application. That is what I am not clear about these units.

THANKS!

[organic farmer]

Are you saying that you want the option of using grid-power or of using solar-power at your discretion?

[SIGP2101]

Are you saying that you want the option of using grid-power or of using solar-power at your discretion?

No, I am inquiring about possibility of using grid tie type of inverter (instead of off grid type of inverter) hooked up to 36 volts battery bank on its DC side and 110 volts fridge on its AC, side for example.
Battery bank will be charged by PV array + CC.

[littleharbor]

The OP is referring to using one of those cheap Chinese plug into the wall 120 vac grid tie inverters, I think. Short answer, don't. They are not UL listed and can be a fire hazard. Buying batteries and related charging equipment to do this is a losing proposition. You will never save enough in electric bills to compensate for the cost of said equipment.

[organic farmer]

I guess I am just dense today, sorry.

[SIGP2101]

You will never save enough in electric bills to compensate for the cost of said equipment.

Thought this was off grid part of the forum. isn't it? If you didn't read my posts i suggest you do so. I do apologize in advance since my intention is not to be rude.
All inputs are highly appreciated.

SIGP2101

[jflorey2]

I want option # 1 from your list - but I want to use grid tie inverter instead of off grid inverter since off grid type of inverter is hard to find in 36V DC in acceptable quality. Grid tie inverters are many in 36V on DC side. Do you implying in your option # 1 that is possible to use grid tied type of inverter?

Not unless you really understand what you are doing - and so far you do not.

There are small inverters like the Enphase M250 that will work from 27-39 volts. These CANNOT have batteries attached to them. To use them with an off-grid system you would need a bidirectional 240 volt inverter like the Radian (to generate the AC that the Enphase inverters need to sync to) and several relays to disconnect the Enphase inverters as the batteries get close to full charge. You would also need some custom controls to provide the level of resolution you need to control charge. For the Radian you are looking at $2500 or so.

I am inquiring about possibility of using grid tie type of inverter (instead of off grid type of inverter) hooked up to 36 volts battery bank on its DC side and 110 volts fridge on its AC, side for example.

Won't work.

Battery bank will be charged by PV array + CC.

Then use option 1. PV array -> charge controller -> battery -> standalone or hybrid inverter. You cannot use a grid tie inverter for that purpose.

[SIGP2101]

I guess I am just dense today, sorry.

Nothing to be sorry about at all.

[SIGP2101]

Then use option 1. PV array -> charge controller -> battery -> standalone or hybrid inverter. You cannot use a grid tie inverter for that purpose.

So hybrid inverter is solution - what ever that thing may be. My feeling is that you are referring to inverter/charger type of inverters. Search is on.

Thanks!

[jflorey2]

So hybrid inverter is solution - what ever that thing may be.

Well, for you, your best option is a standard off-grid inverter. They are reliable and cheap and are designed for what you want to do. I strongly suspect you do not want an AC-tied system (only reason you'd need a hybrid inverter) and are just confused as to what that entails.

[SIGP2101]

Well, for you, your best option is a standard off-grid inverter. They are reliable and cheap and are designed for what you want to do. I strongly suspect you do not want an AC-tied system (only reason you'd need a hybrid inverter) and are just confused as to what that entails.

not quite - I will quote myself:

Reason why I am asking this is because there are so many more available to chose from in 36V DC world than in off grid 36V DC world.
Before I pull the trigger on el cheapo unit I was looking if anyone has successful experience to share. Such a case would open up whole new world of possibilities for me.
Second reason is that some of the grid tie type of inverters by default can run on a range of voltages(22 to 60V). This would also have positive impact to flexibility of my off grid system. 24-36-48 volts battery banks for example.