Alternative Technology Assn Forums

1. 

   carls75
   Member

   Hi, sorry, new to this forum and new to solar power. Some Background: We are in the process of paying for a 4kW system to be put on our home on the Mornington Peninsula in Victoria. My father recently had a 3.6kW system installed (18 panels + inverter) from the same company for approx $13500.

   We've been quoted for a 4kW system $16500 approx. However, I'm somewhat confused. We are getting the same inverter and the same number of panels as my fathers system.

   When we questioned it we were advised that a 3.6kW inverter would "handle" 4kW, but to me we are being taken for a ride to the tune of $3000.

   Can someone set me straigh by explaining how this works?

   Any advice in laymans terms would be greatly appreciated!

   Thanks.

   Posted Wednesday 17 Mar 2010 @ 4:24:28 am from IP #
2. 

   rsigmund
   Member

   3.6kW inverter would "handle" 4kW

   My interpretion is that the inverter voltage and current limits would not be exceeded damaging the inverter if supplied with 4kW of panel output....

   Your inverter in this case will output only 3.6kW maximum

   The problem here is you are paying for extra panel/s of output but won't get the benifit. Also consider you may also be limiting your upgrade capability because to inverter is already sized at the limit.

   Posted Wednesday 17 Mar 2010 @ 5:59:25 am from IP #
3. 

   LanceTurner
   Key Master

   Yes, that's correct, the inverter simply won't draw the full available power from the panels and so part of the capacity you have paid for is wasted. Having said that, if 3.6kW is the output of the inverter, then it probably wouldn't have produced much more than this into the grid from a 4kW array anyway, as you have to allow for inverter losses, which can be up to 10%. However, there are times, such as when you have cool days with light cloud and long sunny breaks, where the array will produce considerably more than it's rated output, and for quite long periods on some days, so this extra generated energy would be wasted.

   Running inverters at their maximum limit for so long each day is an iffy practice at best, it seems to have become common in the renewables industry, but in any other industry it would be frowned upon. You should always allow some capacity overhead on all electrical/electronic devices, it's just good design practice.

   Posted Thursday 18 Mar 2010 @ 1:48:57 am from IP #

RSS feed for this topic

Reply

You must log in to post.