additional 12v circuit for non-essential loads

[frater secessus]

Agreed. Thanks for bearing with me.

 

[GotSmart]

It is in the details.  

Solar technology is improving all the time.  Panels are getting smaller, lighter, and capable of producing more power.  The system I installed just last year at RTR will function for a lot of years, but today can be built cheaper and with better components.     

You have an excellent grasp of how things function in a book situation (Which I don't have anymore) but I was taught by the Renogy corporate, the details that make a system work in all conditions.  

Designing a system that runs at full capacity is just slightly less expensive initially than building a system that has a lot of power to spare.  

I wish my mind was functioning like it used to.  Brain Farts (stroke) suck.  

In 10 years, what can be built will be a lot better.  Do your designing, but get the components at the last step.  

Remember the 8 Track?  Portable tunes in the 70's  One album, (about 15 songs) in a unit the size of a paperback book.  Portable players were called Boom Boxes, and were the size of a 20 quart ice chest.  On my phone I have a chip smaller than my fingernail that has more than 4,000 songs.  My music player can make calls, do banking, send messages, take and hold thousands of pictures and send them around the world in seconds ~~~  You kids have it made.  Every year things get better. Use less energy, and so on.

I remember when ~~~ Never mind.     

Keep asking the good questions that make us think.  No improvements can be made unless someone asks, "Will this work?"

That is the reason for my signature. One idea can change history. Fear the wizard.

 

[frater secessus]

A couple of things have occurred to me in the interim:

The MPPT controller is capturing a ton of power from the panels during Bulk but we are "wasting sunlight" in Acceptance and Float.

Ughhh, unfortunate wording.  Anyhow, 

1. I neglected to notice that PWM is also capable of servicing house loads outside of bulk, just not as much as MPPT can in mppt-favorable conditions.   
2. the possible upside of a discretionary circuit (or manual use of loads during ABS/FLOAT) goes away if/when we move to LiFePO4 chemistries, which have no charging stages.

 

[blars]

[*]the possible upside of a discretionary circuit (or manual use of loads during ABS/FLOAT) goes away if/when we move to LiFePO4 chemistries, which have no charging stages.

While LiFePO4 charging is simpler, it still has a constant current (as much as you can give them) and constant voltage (until the current tapers off) parts. After that, ALL the power from your solar is available for your loads.

 

[frater secessus]

I wasn't very precise there, for sure.  I was referring to the effective lack of Absorption phase at Fractional C charging rates, and no real float.  

BTW, I've tried to summarize your approach to LFP charging here; please advise if I am off-base.