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).
 

Supervstech

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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.
 

Jordi

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Oct 13, 2020
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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.
 

Jordi

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Oct 13, 2020
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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.
 

solar8484

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Mar 4, 2021
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What are the inverter specs?

Grid tied inverters typically have a minimum startup DC voltage. Your panel output may be too low for that.
 

Jordi

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Oct 13, 2020
Messages
222
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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