Hi

Sorry I have so many questions while starting out on this solar journey. I want to know how when an inverter is connected to a DB board it uses the pv power before drawing from the municipality? I am looking at using  microinverters so do these work the same when feeding into the Db board.

Collectively, they work  the same as a single bigger gridtie inverter, with the exception that the MPPT is at panel level.

Edited April 11, 20197 yr by phil.g00

23 minutes ago, Greglsh said:

I want to know how when an inverter is connected to a DB board it uses the pv power before drawing from the municipality?

In a nutshell, PV inverters work by synchronizing to the incoming sine wave, then they effect a power transfer to that incoming system.

Electrical power is transferred by increasing voltage or by effecting a phase shift or both, just like the effect a load would have, but opposite in magnitude and direction.

 

Hi Phil

Thanks for the explanation, I always thought maybe it did some sort of blocking of the main supply. So when the micro inverters can't provide enough power, will the municiple electricity "top up" or does the inverter turn off and the whole load gets supplied by the mains?

9 minutes ago, Greglsh said:

Thanks for the explanation, I always thought maybe it did some sort of blocking of the main supply. So when the micro inverters can't provide enough power, will the municiple electricity "top up" or does the inverter turn off and the whole load gets supplied by the mains?

Lets call the system a dam, you have a pipe flowing into the dam from your gutters and a pipe flowing out of the dam to your taps.

A lot of other people also have pipes into and out of the same dam.

The flow rate in both your pipes will change all the time, sometimes you will fill the dam and sometimes you will empty it.

No just think of it as actually being only one pipe, that can flow both ways.

 

I always think of the power injected by a grid-tied inverter as the butter on top of a slice bread. The bread is the very hard voltage from the grid. The butter is your own generation layered on top. When you bite into it, your teeth hits the butter first 🙂

In reality, all the grid-tied inverter does (of which micro-inverters is just a ... uhm... micro-example), is to work at a voltage a little higher than the grid voltage. Not much, 5V-10V or so. Like water flows downhill, so does this power... and your own loads are closer than the transformer down the street, and since electricity takes the shortest path, the effect is that your own loads are powered by your own generation.

5 hours ago, Greglsh said:

will the municiple electricity "top up" or... 

Yes, micro inverters like all grid-tie inverters will blend utility and PV power to power the loads. 

Make sure whatever inverter you do get, is NRS 097 approved.

So what's the point of having many small inverters instead of one big one?

53 minutes ago, DeepBass9 said:

So what's the point of having many small inverters instead of one big one?

Pros: Panel level tracking (ie no shading issues), AC is made on the roof so the cabling going up there is thinner. Simple to start small and add capacity (you can start with one panel and micro-inverter).

Cons: Costs more overall, your inverter lives in a very hostile place (under the hot panel).

Basically all the same arguments as for SolarEdge... except you can start smaller (good), and the whole inverter is on the roof, not just the boost stage (bad) 🙂