Few larger or more smaller

Re: Few larger or more smaller

Not more effective, but if you have 2 or less strings, you will not need to have a fuse or breaker for each before the charge controller, and MPPT charge controllers works most efficiently at about 2x the battery voltage, so 2 strings of 250 volt panels at 30 vmp would mean no breakers and slightly more effiecent than 2 strings of 3 - 175 watt panels at 30 volts vmp, and less wiring and breakers than 3 strings of 2.

Re: Few larger or more smaller

Novaz wrote: »

for a given power output say 1kw
would 4*250 watt panels be better than 6*175 watt panels

I think it's more likely that you will get 1 kw out of 6*175 (1050 watts) than 4*250 (1000 watts).

I think that fewer, larger panels means less potential points of failure.

Photowhit is correct that if you have only two strings you do not need combiner or breakers, but i recommend a combiner and breakers in all systems. A combiner is a good place to put a lightning arrestor, and breakers at the array, even for only one string, are a convenience and troubleshooting tool.

As Photowhit mentioned, if you want only two strings (no combiner required) and you use the 175 watt panels, you must put them three in series. That means you will have a higher string voltage and your controller will be less efficient. Is that a good idea? Depends on the distance between the array and the controller. If the distance is extremely long, you can save money on the cable by using the higher string voltage.

--vtMaps