Real life panel output vs rating and the Schneider mppt 60-150 controller?

new2PV

Hi, just wondering how to size my array. I want to go with 260w panels x 15 this will in theory give me 3900 watts. In real life what wattage would I expect to get? My mppt 60-150 will only output 3500 watts and it can have up to 6720 watts of array hooked to it. Question do you think my 15 panel size would be a good number to output 3500 watts, or should i be adding a few more panels to the system or is 15 a waste of time stick with 12? Looking for a good solid output..

BB.

A conservative equation for good quality MPPT controller would be (and even close enough for PWM controllers):

• 3,900 Watts STC rating * 1/0.81 solar panel derating * 0.95 typical MPPT controller eff = 3,001 Watts typical maximum output on a sunny summer day
• 3,900 Watts STC rating * 1/58 battery charging voltage * 1/0.81 solar panel derating * 0.95 typical MPPT controller eff = 51.7 amps typical maximum output on a sunny summer day

You may do better (clear/cold mountain top) or do worse (sea level, hot, humid, hazy day).

But for average predicted/observed output--Works close enough (within 10% of predicted/measured output is pretty much dead on in Solar without using lab equipment and measured solar insolation).

-Bill

Photowhit

You can likely look up the Normal Operating Cell Temperature (NOCT) Values for your solar panels. Search for your solar panel in google and add pdf. Look for a spec sheet, Often the NOCT values are listed. I personally think there has been a lowering in the last 10 years or so, I think now 75% of the panel rating would be typical, but some are as high as 85-90%. This would be the starting point that Bill is using above...

If you add your system info in a signature line it would help us figure things out.

Dave Angelini

Commercial folks are going as high as 30% more rated panel than the inverters or controllers are rated and costing the wiring size down into the inverter or controller and up on the outputs within reason.

Remember in the old days when we were warned against doing this. Ah yes more science.

For the OP, you are using a $500 dollar controller and at some point if you run this very nice piece of electronics at full output for years you might need a spare. You have to balance that if the controller is in a hot environment or running grid-tie which tends to be harder on electronics than offgrid. Planning now for a second controller might save you time later because you already sound like you will want more solar.

new2PV

Thanks, looks like I will have to use the NOCT (189 w) values, but it that means 260 watt x 18 panels and 6 strings....Int he future I will be expanding the system I will need more MPPT60-150s for sure. I could have went with a classic 150 but I don't like it lacks the communications of the Xanbus nextwork, and it uses fans for cooling.