12V to 24V Step-up Converter

[ChargeMPPT]

Forgive me for asking a question I should know the answer. I have a 12v battery bank and a 12v~30V DC 200Watt Grid tie inverter. Will the grid tie produce more power at 24 volts or am I over thinking this seems the grid tie only pulls 5amps on my 12Volt system at the most which is only 12V X 5A = 60Watts or is my math all wrong. I was thinking of putting a step up converter 12v to 24V 250Watt and that would bring the Grid tie up to 24Volt x 5A = 120Watts or am I just wasting solar electricy? Thanks for any Replies

[sensij]

What are you trying to accomplish? Why are you feeding batteries into the grid?

What model inverter are you using? Changing the battery voltage should not change the power, but if this is an ebay special, anything is possible.

[ChargeMPPT]

What are you trying to accomplish? Just trying to see if I can lower my electric Bill a bit.
Why are you feeding batteries into the grid? I should have clarified that a bit better. I have ebay special NOT MPPT fake MPPT40 charge controller connected to a 12V battery bank. The grid tie is connected to the Load of the MPPT40 charge controller (manual says the Load can handle up to 40amps) But I only ever see about 5 amps from the grid tie load. I have another ebay special same brand Grid tie but 1000W same setup and it pulls about 12V x 17A = 204Watts . Just Curious if I fed the 200W Grid tie 24v would it produce more power?

[jflorey2]

I should have clarified that a bit better. I have ebay special NOT MPPT fake MPPT40 charge controller connected to a 12V battery bank. The grid tie is connected to the Load of the MPPT40 charge controller (manual says the Load can handle up to 40amps) But I only ever see about 5 amps from the grid tie load. I have another ebay special same brand Grid tie but 1000W same setup and it pulls about 12V x 17A = 204Watts . Just Curious if I fed the 200W Grid tie 24v would it produce more power?

I have never seen a cheap Ebay grid tie inverter that was intended for use with batteries. If you are using one with a battery you are likely using it incorrectly, and any power that gets transferred is likely an accident.

[Sunking]

What are you trying to accomplish? Just trying to see if I can lower my electric Bill a bit.

Complete nonsense. Anyything you take off grid will cost you 5 to 10 times more than buying it.

What you are doing is with battery cost alone cost you roughly 60 to 70 cents to generate and store a Kwh. Then in your infinite wisdom you sell that Kwh to the POCO for 15 cents. You are loosing 50-cents for every Kwh you use from or sell to the POCO. Not very smart.

[ChargeMPPT]

I have never seen a cheap Ebay grid tie inverter that was intended for use with batteries. If you are using one with a battery you are likely using it incorrectly, and any power that gets transferred is likely an accident.

The charge controller is connected to Three 100Watt Panels in parallel and a 12Volt Battery Bank Not sure if the voltage is coming from the batteries or the three panels. As this is a ebay special charge controller call MPPT40.

[Logan005]

You have the makings for a disaster. nothing makes sense. FIRE, now that would make sense.

[inetdog]

What are you trying to accomplish? Just trying to see if I can lower my electric Bill a bit.
Why are you feeding batteries into the grid? I should have clarified that a bit better. I have ebay special NOT MPPT fake MPPT40 charge controller connected to a 12V battery bank. The grid tie is connected to the Load of the MPPT40 charge controller (manual says the Load can handle up to 40amps) But I only ever see about 5 amps from the grid tie load. I have another ebay special same brand Grid tie but 1000W same setup and it pulls about 12V x 17A = 204Watts . Just Curious if I fed the 200W Grid tie 24v would it produce more power?

Since nobody else has said it yet:
Any grid tie inverter which is cord and plug connected to your electrical system is not UL listed and is not legal for use in the US. It is legal for them to sell it but not for you to install it. In any case, it is not safe. Period. If you are very lucky that only thing that will be burned when it fails will be the GTI itself.
To add to that, the ones you find on eBay or direct from China are generally not very efficient and do not operate well. I remember watching a YouTube video of a DIYer who had 150W of panel and a 200W plug and pray GTI. He was getting so little power out (less than 80W as verified with a Kill-A-Watt meter) that he planned on getting a second 200W GTI to run in parallel in hopes of getting more output. (An even worse idea!)
And worse, any small GTI with an input voltage range specified is likely to have an MPPT type input for direct connection to panels and the battery voltage from a 12V system is probably at or below the design operating range.

One more thing: In name brand solar CCs the Load output is typically designed for lighting loads or to operate a relay to control diversion loads when the battery is charged. Even if your CC can provide 40A on its Load output it is likely that the voltage will be lower than what you would get connecting directly to the battery bank. On the other hand, a GTI with MPPT input could damage itself or the battery if fed from a "hard" (constant voltage) supply like a battery rather than the current limited output of the panels.

I am happy to discuss the theory and practice behind this if you wish, but know up front that there is no way to make the system that you describe safe.

[Sunking]

Since nobody else has said it yet:
Any grid tie inverter which is cord and plug connected to your electrical system is not UL listed and is not legal for use in the US. It is legal for them to sell it but not for you to install it. In any case, it is not safe.

I caught it, but it is a moot point. The OP is completely clueless, and being legal is the least of his worries. He has no idea he is giving money away and putting his life and home in danger. The survivors will worry about the legal part when they find out insurance will not pay a dime. In the mean time let him throw money away giving power away to the POCO.

[ChargeMPPT]

Since nobody else has said it yet:
Any grid tie inverter which is cord and plug connected to your electrical system is not UL listed and is not legal for use in the US. It is legal for them to sell it but not for you to install it. In any case, it is not safe. Period. If you are very lucky that only thing that will be burned when it fails will be the GTI itself.
To add to that, the ones you find on eBay or direct from China are generally not very efficient and do not operate well. I remember watching a YouTube video of a DIYer who had 150W of panel and a 200W plug and pray GTI. He was getting so little power out (less than 80W as verified with a Kill-A-Watt meter) that he planned on getting a second 200W GTI to run in parallel in hopes of getting more output. (An even worse idea!)
And worse, any small GTI with an input voltage range specified is likely to have an MPPT type input for direct connection to panels and the battery voltage from a 12V system is probably at or below the design operating range.

One more thing: In name brand solar CCs the Load output is typically designed for lighting loads or to operate a relay to control diversion loads when the battery is charged. Even if your CC can provide 40A on its Load output it is likely that the voltage will be lower than what you would get connecting directly to the battery bank. On the other hand, a GTI with MPPT input could damage itself or the battery if fed from a "hard" (constant voltage) supply like a battery rather than the current limited output of the panels.

I am happy to discuss the theory and practice behind this if you wish, but know up front that there is no way to make the system that you describe safe.

Thanks that's all I wanted to know, So the GTI connected to the CC is like you said limiting the voltage to the GTI that's why I'm seeing only 5amps and if connected to the panels it would see a voltage of 14~17 got it Thanks so much

[jflorey2]

The charge controller is connected to Three 100Watt Panels in parallel and a 12Volt Battery Bank Not sure if the voltage is coming from the batteries or the three panels. As this is a ebay special charge controller call MPPT40.

Forget the charge controller. Is the INVERTER safe to use with batteries? I doubt it very much.

[ChargeMPPT]

It was just a experiment. Like inetdog said the wattage produce is so low (verified with a Kill-a-watt meter) maybe enough for TV for about a hour. It's not even worth it. Sending this GTI back. My main PV system is two MPPT Renogy 40amp Charge controllers, two strings of four 250Watt Panels in series giving me 2KW. I have twelve 80Ah AGM batteries for 5760W 24V config. 3000Watt inverter runs pretty good with just a Full size Refrigerator, small chest freezer and computer and some lights 24/7 a day.