diy solar

diy solar

A very simple scenario - on a budget would you go Series or Parallel and why ?

Budget is king in small systems. Infinite budget, small roof space MPPT. Very limited budget and economics per watt comes into play. You may be better off getting a pwm controller (if on a very bare bones budget) and using money saved to put towards an extra panel or briefcase that can be ground deployed (or just pocket it). The 30 percent quoted is typically overblown, renogy for example states a max 15 percent increase in output (usually at extremely cold temps at that). On average, in parallel, an mppt might add 5 watts per 100 watt panel. I like MPPTs, but I also have a pwm on a small system and it has performed well enough for my needs.

Or pivot completely. Buy a single used or leftover residential panel that will fit your space and an economical mppt (30a Duoracer is my current small system favorite as it can also maintain your starter battery if you keep the house battery 12v). The combo might be comparable in cost to two small panels plus mounting and connectors with a PWM.

True.
Many people hear what they want to hear. I'm not immune. Also I think too many people have started with or used really cheap PWM controllers and thought all pwm controllers are the same.
My reading also suggests many people fall for the claims about 30% more power from mppt when the reality is what you just said is more accurate.

30% more "is possible" under ideal conditions, but those are not abundant or the average.

I happen to have a Xantrex C40 PWM controller and it does amazingly well. Better than some higher end mppt controllers according to some reviews on Amazon.

I happen to have a Epever Triron 4210N mppt controller and I'm trying to come up with a test to see which one actually provides the most power and by how much but these things are subjective. Temperature, angle of the Sun etc.

That said, above 150watts I would go with mppt. But the thread is specifically about low power systems. two 100watt panels are not often going to provide 150watts to the controller after losses are they? Maybe so according to one of Will's videos.

mppt probably the better choice overall. PWM if you're on a budget like you said, or for very low power systems.
 
Back
Top