grid tie relationship in stand alone

grd

New Member
If you ask online about "grid tie in stand alone system" the assumption by search engines is that you want to use a grid tie inverter without a grid (cheat)
Which is not what I want to get info on.
In a stand alone, panels, battery, inverter, running a house system but no grid going past the front door. So you have a grid and a gti from a string of panels feeds it to your "grid". As well as other pv inputs charging via inverter mttp. Really simple.
You can do this and it works fine. But you cant limit input from the gti because it requires a current sensor ( which comes with the gti) but you cant use it because there is no "other grid" for it to be oriented towards in installation. It just keeps on pouring in power, more than house is drawing.
So it will cause an overvoltage fault in the inverter eventually, like late morning when the batteries are getting full. You have to isolate that string manually. On a dull day it can stay connected.
Is that right, it was done rather than run extra 15metres of dc to parallel to the inverter mppt but think now that would be the best thing to do?
 

stienman

Solar Addict
There is an entry point for the "grid" - it's the output of the main inverter.

If you put the current transformer on the output of the main inverter, and tell the grid tie inverter that it should "export" zero energy, then it will provide as much power as it can without forcing power to flow into the main inverter.

Thus the main inverter should not experience surge/overvolt conditions.
 

grd

New Member
There is an entry point for the "grid" - it's the output of the main inverter.

If you put the current transformer on the output of the main inverter, and tell the grid tie inverter that it should "export" zero energy, then it will provide as much power as it can without forcing power to flow into the main inverter.

Thus the main inverter should not experience surge/overvolt conditions.
Thanks much for that, can see the logic. Only problem being the current sensor has to be at the inverter and their cables are limited in length.
The array we are talking about is from a shed and connecting to circuit at end of house closest shed.
 
Top