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Grid tied inverter start-up power

Jordi

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Oct 13, 2020
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Dear all,

I have been testing setups with 2 Aliexpress MPPT 500-600W grid tied inverters but for now I have not been successful at sending any electricity to the grid from solar panels. A 12V inverter I use with a 100W panel and a 24V inverter I use with 2 12V 100W panels in series.

The rootcause for such problem is the poor orientation of the panels and not a single day of sun.

Ok, I will wait for a sunny day but meanwhile I have a question. Are you familiar with the startup power of cheap MPPT grid tied inverters?
Even though it is cloudy, I still register a production of 3W (more than the stand-by consumption: 0,7-1,5W); why am I not sending 0,5-1W?

Or question reformulated: Is there any small solar installation owner (<300W) that can tell me what happens in cloudy days? Are you having electricity pushed to the grid during cloudy days? (For bigger installations >1KW it happens).
 
Cloudy days can limit production over 90%, so… 3 to 5 watts isn’t unusual… depends on the clouds.
Winter cloudy weather isn’t ideal for solar.
 
Thank you Super,

I could not find any specific information regarding this question so my best shot is to wait for a sunny day.
If I make it to produce 10W, even If for just 5 minutes, I hope the inverter does turn on and send electricity back to the grid.
I will post then a reply here.
 
Can you put a load on the inverter to see what the output might be? What are you using to measure output?
It is a grid tied inverter so the load is the grid; there I measure 1,5W which is the stand-by consumption from the inverter. I have a AC-meter for that.

If you meant to put a supply to the inverter like a battery I did already and it works well. I was outputting 170W to the grid.

One of the two inverters I have has a capacitor which chargers over time (3-4 minutes); then the inverter is activated for 2 seconds in which the capacitor energy is discharged and back to stand by mode. The discharge is so brief it does not dump energy to the net at all.
 
What are the inverter specs?

Grid tied inverters typically have a minimum startup DC voltage. Your panel output may be too low for that.
 
I have 2 inverters both with the same situation.
Inverter with voltage range 22-60V hooked up to two 16V panels in series (100Wx2). No-load consumption 0,7W
Inverter with voltage range 10,5-30V hooked up to one 18V panel (100W). No load consumption 1,5W

No specs for startup wattage. Both MPPT function. Both operational with a battery.

I have asked a friend to share the output of his professional installation (2,26KW) and during this cloudy days has been even less than 5%. So I guess the inverter needs 5W or so and I am only giving it 3W max. Will wait for sunny days. Solar in the north of Europe and during dec-jan-feb kind of sucks I see now...
 
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