To combine or not to combine, that is the question

sprintman

The more I try to learn the more confused I feel. I am starting with a small system. Either 3-215 watt 28v panels or 4- 195-200 watt 28v panels. I am thinking I would mount these in series 1) because I can run a lighter wire to the controller and 2) because if I understand correctly a series array will perform better on cloudy or overcast days. I will use an mppt controller. A 12v battery bank. If this goes well down the road I could see doubling the above set up, and going to a 24v battery bank. Do I need a combiner to get started with the first part of the system? As an aside have any of you looked at the combiner you can build.....looks simple and inexpensive, its under projects at Freesunpower.com. Can anyone tell me what size breakers I would use for the above panels. Do you use a combiner when you wire an array in series or is that just for when you wire two or more arrays (that are in series) together. Thanks for your input.

ggunn

Re: To combine or not to combine, that is the question

sprintman wrote: »

The more I try to learn the more confused I feel. I am starting with a small system. Either 3-215 watt 28v panels or 4- 195-200 watt panels. I am thinking I would mount these in series 1) because I can run a lighter wire to the controller and 2) because if I understand correctly a series array will perform better on cloudy or overcast days. I will use an mppt controller. A 12v battery bank. If this goes well down the road I could see doubling the above set up. Do I need a combiner to get started with the first part of the system? as an aside have any of you looked at the combiner you can build.....look simple and inexpensive its under projects @ freesunpower.com. Can anyone tell me what size breakers I would use for the above panels. Do you use a combiner when you wire and array in series or is that just for when you wire two or more arrays (that are in series) together. Thanks for your input

The role of a combiner is to group the output of two or more strings, so if you have only one string, you don't need a combiner. If you don't want to run your USE-2 all the way to your controller, you could use a pass through box to change your wiring over. I have never heard of series modules performing better on cloudy days, but series wiring will allow you to use thinner wire. If you combine strings and fuse/break them (although you don't need to if you are only combining two strings), the fuse/breaker size for a string is the next standard size up from (1.25)(1.25)(Isc). Isc for a string is the same as for an individual module.

solarix

Re: To combine or not to combine, that is the question

You don't need a combiner until you have 3 or more strings in parallel.