Solar/Generator Charging

[johnny666]

Hi all ....
Question re solar charging (through a MPPT controller).
What happens when the generator is running and charging the batteries ?
Does the controller disconnect the solar, or does it add to the total charge ?

[smac999]

it will add

[john61ct]

Any number of disparate sources can be stacked NP

[travellerw]

Originally Posted by johnny666

Hi all ....
Question re solar charging (through a MPPT controller).
What happens when the generator is running and charging the batteries ?
Does the controller disconnect the solar, or does it add to the total charge ?

If your batteries can take the extra current, then it will add.

When we had our FLA bank, those batteries couldn't take the extra current so there was often "fighting" between the controllers/charger. Our charger would sense a drop in current as the solar began putting in amps in the sun and goto float. It was frusterating if it was cloudy as the charger wouldn't switch back without a reset. We could turn the solar off to avoid the issue, but that was a big waste.

With our LFP bank, the batteries gobble up everything all the charge sources can throw at it. We often see around 110A going in if we are running the gen/charger and its a very sunny day (60A from the charger and 50A from solar).

[john61ct]

Yes best if all charge sources are custom-adjustable if trying to get efficient output from them all at once.

Ideally from your smartphone as with Victron's Smart stuff.

But usually a big alt setup or mains charger makes the solar input pretty irrelevant anyway, especially with LFP.

[travellerw]

Originally Posted by john61ct

Yes best if all charge sources are custom-adjustable if trying to get efficient output from them all at once.

Ideally from your smartphone as with Victron's Smart stuff.

But usually a big alt setup or mains charger makes the solar input pretty irrelevant anyway, especially with LFP.

Hmm.. I have told you this before, you are REALLY out of touch with reality. I have no idea where you are getting your information. It chokes me, as your statement is FAR from reality for anyone I know running LFP. Please provide me some data to backup your "usually" statement! How many full time liveaboards do you know with LFP? Please don't quote other threads (that you can't remember) as your source. Frankly, I don't even think you have an LFP bank. If you do, there is no way you have actually lived off grid with it!

Full time liveaboard (3 years) with a family of five and LFP.. Solar far from irrelevant on our boat. Actually, solar provides over %90 of our power. There are at least 5 other boats anchored near us with LFP banks. Same is true for them, solar is the #1 input.

[Bleemus]

Originally Posted by travellerw

Hmm.. I have told you this before, you are REALLY out of touch with reality. I have no idea where you are getting your information. It chokes me, as your statement is FAR from reality for anyone I know running LFP. Please provide me some data to backup your "usually" statement! How many full time liveaboards do you know with LFP? Please don't quote other threads (that you can't remember) as your source. Frankly, I don't even think you have an LFP bank. If you do, there is no way you have actually lived off grid with it!

Full time liveaboard (3 years) with a family of five and LFP.. Solar far from irrelevant on our boat. Actually, solar provides over %90 of our power. There are at least 5 other boats anchored near us with LFP banks. Same is true for them, solar is the #1 input.

The OPs question was regarding "when the generator was running" not how relevant solar is overall. John answered correctly.

[newhaul]

Originally Posted by travellerw

Hmm.. I have told you this before, you are REALLY out of touch with reality. I have no idea where you are getting your information. It chokes me, as your statement is FAR from reality for anyone I know running LFP. Please provide me some data to backup your "usually" statement! How many full time liveaboards do you know with LFP? Please don't quote other threads (that you can't remember) as your source. Frankly, I don't even think you have an LFP bank. If you do, there is no way you have actually lived off grid with it!

Full time liveaboard (3 years) with a family of five and LFP.. Solar far from irrelevant on our boat. Actually, solar provides over %90 of our power. There are at least 5 other boats anchored near us with LFP banks. Same is true for them, solar is the #1 input.

solar is not the #1input when my generator is running .
I have 400 watts solar . But I can run up to 50 amp charger off my generator so with generator running it will effectively more than double what my solar can produce.

That being said yes my solar is my primary charge source. ( don't like running any dino juice charge source unless needed .)

[travellerw]

Originally Posted by Bleemus

The OPs question was regarding "when the generator was running" not how relevant solar is overall. John answered correctly.

I will disagree with you there. John did not answer correctly. Just quoting things he reads elsewhere. No actual real world experience. I will back that statement up too. Just google "John61ct forum". It will be an enlightening read for you.

Why is solar irrelevant "when the generator is running"? I have 900W of solar on my boat, so even when the generator is running, my solar can and does double my input (with LFP). The fella behind me has 800W on his monohull, similar story with his LFP bank. I would say that is far from irrelevant.

[travellerw]

Originally Posted by newhaul

solar is not the #1input when my generator is running .
I have 400 watts solar . But I can run up to 50 amp charger off my generator so with generator running it will effectively more than double what my solar can produce.

That being said yes my solar is my primary charge source. ( don't like running any dino juice charge source unless needed .)

Yes, your charger is double your solar. However your solar is far from irrelevant while the generator is running. It can still contribute roughly another 25A to the total output (unless its dark out). Not sure I would call %30 of total output irrelevant.

[newhaul]

Originally Posted by travellerw

Yes, your charger is double your solar. However your solar is far from irrelevant while the generator is running. It can still contribute roughly another 25A to the total output (unless its dark out). Not sure I would call %30 of total output irrelevant.

I did not say my solar was irrelevant I said with the generator running it was not my primary charge source. Also when have you actually seen solar put out rated power for any significant time period.

[GaryBode]

Check with the manufacturer of both pieces of equipment. They may recommend to NOT do what you are doing.

[sailorboy1]

Originally Posted by johnny666

Hi all ....
Question re solar charging (through a MPPT controller).
What happens when the generator is running and charging the batteries ?
Does the controller disconnect the solar, or does it add to the total charge ?

When I do it
- if the batteries can accept all the current both the solar and battery charger will supply
- if the battery acceptance wouldn't accept my MPPT just senses that the batteries are get charged from the battery charger and it shuts down supply from the solar

[john61ct]

What I said

Originally Posted by john61ct

a big alt setup or mains charger makes the solar input pretty irrelevant anyway, especially with LFP.

To clarify, **if** you have hundreds of amps available from charge sources conveniently available on demand and LFP, then solar becomes unnecessary.

With lead, you still need some solar to finish the long tail, even with kW ICE sources available.

Many smaller boat designs mean lots of solar is difficult, windage issues and ugly.

Obviously there are many strong reasons to go mostly-solar if you want to.

But many people with high AH needs and small boats are not aware that it can be optional if you don't.

None of which has anything to do with "what most people do"

[travellerw]

Originally Posted by newhaul

I did not say my solar was irrelevant I said with the generator running it was not my primary charge source. Also when have you actually seen solar put out rated power for any significant time period.

Location helps.. Right now in Grenada, my solar is putting in about %75 of the rated output (high puffy clouds). Thats about 50A. Down here we see %75 and above for about 3 hours every day.