I noticed that the string size calcs for the Excel spread sheet and the web site are different. The Excel spread sheet gave me: 2 strings with nine panels each. The web site returned 1 string with 10-12 panels at 113 degrees. The Excel program didn't take temperature into account. It gets hot here, 105 in the summer. My system is currently designed for 4 Sunny Boys (2500) with 72 Sharp 165W panels. Each inverter has two strings with 9 panels on each string. Would it be better to have 6 Sunny Boys with one string each and 12 panels for a warmer climate? Thanks.

I did some calculations and can see with the number of panels you have selected and the fact they are 24 Volt not 12 Volts you are not matching well to the SB2500

In your climate you need a minimum of 12 , sharp panels ... I run 24 KC120's and in the summer I am seeing the array at about 300 VDC , add the fact you'll be running even hotter than me , you will have no margin with less panels

So if you stick the the Sharps I would say you will need 6 inverters to match the voltage.

I would stay with the SB2500 even though you are way below its maximum operating level , but the 1800 might be a better match

If you were to use 100 KC-120's , you could use 4 SB2500's with 4 strings of 25 KC-120's for the same power output of the sharps. Only you can decide if the cost savings in two less inverters out weighs the wiring and mounting cost of having 28 more panels.

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