Hi all, first i would like to say that i'm a electronics hobbyist with no formal education on this subject so please bare with me
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I'm working on an idea that i had for some time that consists to attach a battery to a PV system composed by Grid-tie micro inverters. I have the system working but i'm having troubles on the "charging" side.
Here is a small "schematics" of that part.
![](https://i.imgur.com/2lNmKDq.jpg)
Basically the charging part consists on a DC-DC Boost converter connected in parallel with the Grid-tie inverter so the the output of the solar panel could be used to both produce mains electricity and charge the battery.
What? Why? My goal is when the battery is fully charged the Solar panel output is consumed by the inverter.
Here are some specs:
Solar panel- Power: 250W
Imp: 8A
VOC: 37V
VMP: 31V
DC-DC Boost Converter150W 10A 10-30V to 12-35V Step Up CC CV DC DC Booster Converter
https://www.ebay.com/itm/CC-CV-Buck-Boost-Converter-80W-Booster-DC-DC-Step-Down-Step-Up-Adapter-Adjustabl/253702023584?hash=item3b11d1a9a0:g:YfIAAOSwrU1bK0P2:rk:1:pf:1&frcectupt=true- Input: 10-30V
Output: 12-35V
CV (set to 31V)
CC (about 3A)
UVP (set to about 11V)
Battery Charge Controller10A 12V 24V wincong SL03-10A solar Charge Controllers LCD Li Li-ion lithium LiFePO4 batteries
https://www.ebay.com/itm/SL03-10A-10A-12V-24V-Wincong-solar-Li-ion-battery-charge-controller-regulators/263341720180?hash=item3d5063c274:g:iNQAAOSw32lYvlJW:rk:1:pf:1&frcectupt=trueHere are the problems i'm having:
Sometimes there no AC output and only 0.1A DC outputI think that this happens when the solar panel output voltage is drawn down to about 10V (that is what i get on a volt meter on the solar panel output) by the DC-DC converter and/or the inverter.
I believe that there is no output because the DC-DC converter does not get enough voltage to work and 10V is too low to the inverter.
Also, i have some Clip On RFI EMI Noise Filters Ferrite Core on the input side of the inverter and when this happens they do a high pitch sound and if i apply some pressure one the ferrite cores the sound changes as if they where vibrating.
I've noticed that when this situation happens and if i disconnect the inverter, the DC-DC converter starts to output, some times about 3A, so there is power on the solar panel (and i believe that the solar panel voltage rises).
Sometime if i fiddle with the current limit on the DC-DC converter, without disconnecting the inverter, i start to get some output.
Sometimes few or none AC output and 3-4A DC outputI've noticed this on bright days, when the solar panel should be outputting 6-7A, i get some watts AC (5-20W oscillating) and the DC-DC converter output is 3-4A, oscillating. On this situations if i also disconnect the inverter the DC-DC converter output rises to 6-7A. Again, when the inverter is connected i can notice the high pitch sound on the Clip On Ferrite Cores.
So.. where is the power going?
I've tried a similar DC-DC converter with no UVP and no CC and the result is worst, there is no AC or DC output, only heat on the DC-DC converter and high pitch sound on the Clip On Ferrite Cores...
Is the problem at the DC-DC converter, on my setup or both?
Is this setup harmful to the inverter?
Is there a better way to achieve AC + DC output on this setup?
If not, is there a way to send the power to the inverter as soon as the battery gets full?
Big thanks in advance!
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