solar vs shore

[Andreas W]

I only have the fridge and sometimes a fan running. So with my 400W solar panels I don't need to be on the shore connection.

[sailorboy1]

Originally Posted by USMCOrdO

What is the preference for power at the dock when not aboard, having shore power turned on, or leave off and let the solar panels and MPPT keep the boat powered and batteries charged.


If I use shore power, does it negatively affect the solar panels or MPPT?


Thanks,
Jay
S/V Encore
C36 1993 #1245

I use both.

But since the batteries are always fully charged I change the solar setting to hit absorption voltage to just stir the batteries up and then drop right to float with no absorption hold time. My solar float is a little higher than the battery charger so during the day solar provides the DC and at night the charger takes over.

[slug]

Originally Posted by USMCOrdO

What is the preference for power at the dock when not aboard, having shore power turned on, or leave off and let the solar panels and MPPT keep the boat powered and batteries charged.


If I use shore power, does it negatively affect the solar panels or MPPT?


Thanks,
Jay
S/V Encore
C36 1993 #1245

Corrosion

When you are plugged into shorepower , Your earth wire connects to every other boats earth

You will inherit their problems

If you have the option ...unplug and isolate your boat

[Miguelso]

I prefer to have it on shore power. My rationale is that with my solar system, I would be cycling the batteries and reducing its life. My freezer/refrigerator can lower my battery bank to 90% during the night. Not a deep cycle, but still a cycle every day.

[Bmorgan562]

Originally Posted by Captn_Black

Imo, why risk any extra potential problem when you can just rely on your panels to keep things topped up? Unless you have some big sources of drain connected while you're not there I don't see the point of connecting to shore power.

Im leaning to your opinion, conversely or rather is there a benefit from not being on shore power as it pertains to stray current/electrolysis?

[Bmorgan562]

Originally Posted by Captain Bill

I leave my shore power on to run my AC in dehumidify mode and keep the battery charger in float mode. I would point out one item of caution. My Morningstar solar controller senses "night", that is a time period when no output is coming from my solar collectors, and when the sun comes up it automatically goes to absorption voltage for 3.5 hrs. This controller only detects absorption time and does not read a shunt. This results in severe overcharging of the battery if I leave the solar controller in its normal mode when plugged into the dock. I learned a lesson by frying a set of AGMs by overcharging. I can program this controller with custom charging profiles and made one with the float absorption voltage just .01V above the float voltage. During the day any 12v requirements are easily met by the solar panels while the 120v charger holds the float voltage at night and even though my controller "thinks" it is giving me absorption voltage for 3.5 hours every morning, I am not frying my batteries.

Up till now ive seen 0.!v higher and you are .01v... as long as it value is higher does it matter if it 1/100 or 1/1000ths?

[Johan Leopard51]

Different take from me

Obviously sun is cheaper than marina. Where we marina that is $0.55/kwh

Cost aside : being entirely disconnected (not even plugged in) means you are isolated from their issues. I am 99% certain that our yacht leaking its anode metal into the Indian Ocean is all to do with bad earthing of shore power. We are the sacrificial lamb because we are the path of least resistance.

My proof : on outhaul, we had current between yacht and yard only when yacht was connected to shore power. With cable not just off, but unplugged, zero amps to ground.

[Bmorgan562]

Originally Posted by Johan Leopard51

Different take from me

Obviously sun is cheaper than marina. Where we marina that is $0.55/kwh

Cost aside : being entirely disconnected (not even plugged in) means you are isolated from their issues. I am 99% certain that our yacht leaking its anode metal into the Indian Ocean is all to do with bad earthing of shore power. We are the sacrificial lamb because we are the path of least resistance.

My proof : on outhaul, we had current between yacht and yard only when yacht was connected to shore power. With cable not just off, but unplugged, zero amps to ground.

I’m believing what you are saying but if I have a galvanic isolated.how much different is it??

[sailorboy1]

Originally Posted by sailorboy1

I use both.

But since the batteries are always fully charged I change the solar setting to hit absorption voltage to just stir the batteries up and then drop right to float with no absorption hold time. My solar float is a little higher than the battery charger so during the day solar provides the DC and at night the charger takes over.

Since I wrote that I changed and last 2 years in a marina I just used the solar and only turn on the battery charger if solar had been low for 3 days.

But I had also changed to LFP

[noelex 77]

This is an old thread, but the main problem when running both shore and solar power is that solar controllers will start a new charge cycle (bulk, absorption and float) each solar day. This is not ideal if the batteries have been kept at 100% SOC overnight by shore power.

Some solar controllers have mechanisms built into the algorithm to reduce the absorption time when the batteries are fully charged, but unless you have a very sophisticated system most solar controllers will be overcharging the battery in these circumstances.

The remedy is to manually alter the voltage set points and absorption time to stop this happening.

[barnakiel]

I live in the marina now and I see 99% boats permanently plugged in.


We only get one or two fires now and then, so I think the risk is minimal.


b.