Off-the-grid with grid-tie inverter? - Page 8

buteman · 10-28-19, 08:10 AM

What about using a high power H Bridge wired to a transformer rather than a motor. If the bridge was driven to switch at say 60 Hz could that then be set up to produce a lower voltage output, rectified and fed to a charge controller?
It wouldn't need to do anything other than connect the output from the panels to the H bridge system instead of the inverter.

NiHaoMike · 10-30-19, 11:42 PM

Quote:

Originally Posted by buteman

Thanks for the quick reply Xringer.
Not really studied it. It was installed before we bought the house. It's around 4 Kilo watt and appears to have 16 panels arranged as 2 banks of 8 with 192 volt per chain.

That voltage is right in the range to run a switching power supply from. Just add a connector to allow easy connection if needed.

Most likely the easiest/cheapest way to build a power tap device would be to hack some ATX power supplies. Mod them to output 14.4V for charging lead acid batteries (or 16.4V for 4S lithium, or even 12.3V for 3S lithium), have a current limit to prevent exceeding the rating of the PSU, and add an input voltage control loop to prevent them from trying to pull the input voltage below the MPP rating of the panels.

buteman · 11-03-19, 04:59 PM

Ah yes. never thought of that! I have a few computer psu's knocking about

nokiasixteth · 04-25-20, 10:32 PM

Did you ever get it up and going @xringer. Seems to make it legal you would need a interlocking breaker so when power goes off you can keep from backfeeding the grid during power outage . Next problem would be how to keep from over charging and damaging your batteries . Solar edge can be curtailed with the context sw and xw pro i have read . Also a guy has emphase that does the same.

Xringer · 04-25-20, 11:24 PM

Not really. One of my four 200w PV panels was killed by a falling limb and I used the remaining 600 watts to heat water, until my tank started leaking beyond repair.
Now, I'm using that 600 watts for space heat (2000 BTUh) in the basement.
Grid tie stuff is off the table these days..

nokiasixteth · 04-26-20, 12:18 AM

I just bought the context sw and the nissan leaf lithium batteries to hook up when grid is down for pure offgrid backup in a short term outage. I Dont quite have the money to finish it completely to do the curtailment but do want to see if the frequency curtailment is valid for solar for the grid tied solar edge seen your post was hoping someone knew for sure.

Xringer · 04-26-20, 11:07 AM

I wanted something to work if the grid failed to power sump pumps and a few devices.
Lead acid storage still works, but not sure how many watt hours is available.
To back-up that short term power, I have a gas generator that can provide limited power for a few days.
I only have abt one KW of solar PV, (that's behind too much shade) so I'm never going to use that to augment my grid power.

I'm 74 years old with a bad underlying heart condition, and don't expect to be
around much longer. So my hobby stuff is currently on the back burner.

nokiasixteth · 08-07-20, 10:56 PM

Quote:

Originally Posted by Xringer

I wanted something to work if the grid failed to power sump pumps and a few devices.
Lead acid storage still works, but not sure how many watt hours is available.
To back-up that short term power, I have a gas generator that can provide limited power for a few days.
I only have abt one KW of solar PV, (that's behind too much shade) so I'm never going to use that to augment my grid power.

I'm 74 years old with a bad underlying heart condition, and don't expect to be
around much longer. So my hobby stuff is currently on the back burner.

https://www.victronenergy.com/live/v...s:gx_solaredge

This i found . Obviously after i had already bought a different inverter

Xringer · 08-08-20, 08:29 AM

Thanks for the info. I'll check it out when I get time.
It's the season for maintenance on my heating systems & my back-up power.
I'm babysitting 5 days a week and my weekend leisure time is very limited.

04-25-20, 11:24 PM	#75
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	Not really. One of my four 200w PV panels was killed by a falling limb and I used the remaining 600 watts to heat water, until my tank started leaking beyond repair. Now, I'm using that 600 watts for space heat (2000 BTUh) in the basement. Grid tie stuff is off the table these days.. __________________ My hobby is installing & trying to repair mini-splits EPA 608 Type 1 Technician Certification ~ 5 lbs or less..

04-26-20, 11:07 AM	#77
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	I wanted something to work if the grid failed to power sump pumps and a few devices. Lead acid storage still works, but not sure how many watt hours is available. To back-up that short term power, I have a gas generator that can provide limited power for a few days. I only have abt one KW of solar PV, (that's behind too much shade) so I'm never going to use that to augment my grid power. I'm 74 years old with a bad underlying heart condition, and don't expect to be around much longer. So my hobby stuff is currently on the back burner. __________________ My hobby is installing & trying to repair mini-splits EPA 608 Type 1 Technician Certification ~ 5 lbs or less..

08-08-20, 08:29 AM	#79
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	Thanks for the info. I'll check it out when I get time. It's the season for maintenance on my heating systems & my back-up power. I'm babysitting 5 days a week and my weekend leisure time is very limited. __________________ My hobby is installing & trying to repair mini-splits EPA 608 Type 1 Technician Certification ~ 5 lbs or less..

10-28-19, 08:10 AM	#71
buteman Lurking Renovator Join Date: May 2011 Location: Barrow upon Humber Posts: 8 Thanks: 0 Thanked 0 Times in 0 Posts	What about using a high power H Bridge wired to a transformer rather than a motor. If the bridge was driven to switch at say 60 Hz could that then be set up to produce a lower voltage output, rectified and fed to a charge controller? It wouldn't need to do anything other than connect the output from the panels to the H bridge system instead of the inverter.

11-03-19, 04:59 PM	#73
buteman Lurking Renovator Join Date: May 2011 Location: Barrow upon Humber Posts: 8 Thanks: 0 Thanked 0 Times in 0 Posts	Ah yes. never thought of that! I have a few computer psu's knocking about

04-25-20, 10:32 PM	#74
nokiasixteth Journeyman EcoRenovator Join Date: Jan 2014 Location: Earth Posts: 348 Thanks: 43 Thanked 14 Times in 13 Posts	Did you ever get it up and going @xringer. Seems to make it legal you would need a interlocking breaker so when power goes off you can keep from backfeeding the grid during power outage . Next problem would be how to keep from over charging and damaging your batteries . Solar edge can be curtailed with the context sw and xw pro i have read . Also a guy has emphase that does the same.

04-26-20, 12:18 AM	#76
nokiasixteth Journeyman EcoRenovator Join Date: Jan 2014 Location: Earth Posts: 348 Thanks: 43 Thanked 14 Times in 13 Posts	I just bought the context sw and the nissan leaf lithium batteries to hook up when grid is down for pure offgrid backup in a short term outage. I Dont quite have the money to finish it completely to do the curtailment but do want to see if the frequency curtailment is valid for solar for the grid tied solar edge seen your post was hoping someone knew for sure.