7.2kW solar with 5kW inverter

Sorry, I’m jumping in on this conversation…

We were looking 20x Jinko 370w panels to a SMA SunnyBoy 5.0 - located in New Zealand so don’t have the regulations you guys have with panels to inverters ratios etc. also don’t have as much sun to play with either… hence looking for the additional panels to increase shoulder input.

Confusingly, the 7.2kW array does limit the choice of inverter, where the array size exceeds the input of inverters like Sungrow - even tho it’s within the maximum voltage range…

However, I’m struggling to work out if the SunnyBoy 5.0 is a 5kW or a 4.6kW inverter. The spec sheet seems to imply both.

We reached out to SMA for there input, but the reply was:

The unit is designed to work at 97% of its capacity, you won’t get 100% due to factory reasons.

That results in 4.85kW, however I do wonder if he was meaning the unit is 97% efficient?

Interesting in your insights to this.


Hi @Glazza

The Sunny Boy 5.0 is 97% efficient, so you do lose a bit in the conversion of DC to AC, but if the input is over say 5150W, you should still get an output of 5000W. Shouldn’t be 4.6kW, unless you’ve the inverter is programmed to have that output limited to that for regulatory reasons (as is required in some areas in Australia).

7.2kW into a 5kW inverter is quite a bit oversized. Even though you get a bit less sun there, you’ll still get a fair bit of “clipping”. Why not go a 6kW inverter? Or are you restricted to 5kW? I guess if you are restricted to 5, then oversizing by that much probably makes sense.

Hope that helps.


Hi @Marty

Thanks for your reply. The confusion around of the 4600w comes from the data sheet for the SunnyBoy, where they state the following:


Maybe im reading it wrong :slight_smile:

I am considering the 6kW inverter, however there was only a minimal increase in output… based on a model from HelioScope:


Oh, good detective work. AS4777 is an Aus/NZ standard, but VDE-AR-N 4105 looks like an EU or German standard, so presumably it would only be programmed in if the unit was solar in the EU, but I don’t know. You’d probably need to speak with SMA to confirm.

Ok fair enough. It would be good to get more details about these calcs, but they seem plausible enough. So you’re looking at about 200kWh difference a year. The value of that would depend, but it might be as little as $20 a year, or as much as $50. Not a lot!