Solar Power Denham Court NSW

Hi Marty,
Finally, I have got the PV system installed by Solar Power Nation for $3950.
24 x 330 W Risen Panel : 7.9 kW along with ABB Trio 8.5 kW inverter.
Currently, I am getting around 23-24 kWh energy per day at Denham Court, NSW. The panels are facing north-west side. I have thought the energy generation would be around 35 kWh per day at the end of November for a 7.9 kW system, or is 23-24 kWh reasonable?
Could the 8.5 kW ABB inverter not good for 7.9 kW panels?

Looking forward for your help.

Hi @royritayan,

24kWh does seem a little on the low side. How many days is that averaged for though? We have had a lot of haze because of these bush fires. I would expect around 30kWh a day or more on average in November with a NW install at around 25 degree roof pitch. I wouldn’t be too alarmed yet, because these are averages that we are talking about and bad weather can bring the average down over a particular period. However I would keep a close eye on it over the next couple months.

How much power do you use daily btw?


Solar Power Sydney

Hello @Marty,
Thanks for your reply. It has been around a week, but I am worried for two reasons:

  1. 7.9 kW panels with 8.5 kW inverter might be not a good match
  2. The string 1 produces much less voltage (167 V) than string 2 (369 V) which is unusual as all the panels are on the same roof. Unequal string voltage affects energy production very badly, as far as I understand.

I attach a picture for pitch- if you find anything not right! The roof is facing the north-west side.

Our daily energy consumption is around 15 kWh, but when we turn on the ducted heating/cooling it shoots up to 27-30kWh.


Hi @royritayan

Nothing wrong with the ABB inverter. The problem is the string 1 voltage is way too low and well out of the required MPPT range of the inverter. String 1 will not be doing anything hence why your generation is so low. The total solar generation should be well over 35kWh per day.

This is due to extremely poor design and configuration of the strings. Typically of sales companies who have no adequate training. This needs to be re-wired to work properly. How many panels are the other roof faces?

Refer to the MPPT voltage range in the bottom right hand corner of the ABB spec sheet. As you can see the string voltage (when operating) needs to be above 320V to work correctly.

All the panels on the same roof. In total 24 (330W) panels and for one string I believe should be 12 panels connected as this inverter has 2 strings input.

Thanks for your comment, I was suspecting something wrong with the string voltages, but you are bang on. The installers, I don’t know how do they get CEC certificates- just paying money and attending one seminar?

Thanks again!

Just wanted to thank you all. The installer has forgot to turn on the switch of one of the strings on roof.

A bit of dust and ashes made it less efficient production. I attach the screenshot of the current power generation for last 2 weeks for the 7.9 kW PV system and would be glad to know expert’s opinion about the power generation is acceptable or lower than expected!


1 Like

That’s looking a lot better now @royritayan.