Buying components for flexible design

this question comes up often.  you are correct, you will be losing some efficiency by going with larger than needed components to begin with.  I feel that this is worth it because for most folks, this does two things

1. forces forethought and better system design
2. requires beefier safety/disconnect equipment that can stay the same with system growth

either way is okay, with smaller components, you can limit initial investment.  as you grow you will have to upgrade your balance of system.  it is really easy to do so with somebody else's money, but i think sizing larger components toward your end goal is the way to go.


the only thing to be careful of, is that with mppt controllers, you need the exact same make and model pv to go with it.  because of this you may want to take extra care to select modules that have a stable production run for the future, one that are not slated to be discontinued.

 for example, if I were starting a system that i intended to grow for years, i would take a kyocera 135 rather than a 130 because the 135 has just started production, while the 130 is slated for discontinuing.  if you plan to add on pv as budget allows, having discontinued modules is a real bummer, because it destroys the idea of going big on the controller so as not to re-buy.

james
Alt-E staff

I guess that's a good argument for buying components via a reputable, knowledgeable, and established business.  They might have some insight into production and supply.
It's tempting to shop around on the internet for the cheapest supplier, but I've always found that a cheap source is usually not a good source.