Basic solar system advice - max power on a budget

[Pete7]

Originally Posted by George_SD

It really comes down to your usage and how far you deplete the batteries (remember - solar typically doesn't feed anything, just recharges the batteries).

Not quite. Yes solar charges the batteries, but if you have an inverter and apply a load whilst the MPPT is in float you will see it jump to bulk and provide as much solar power as possible for the inverter and only then take any balance needed from the batteries. The same thing happens without the inverter, solar is used to run boat and any surplus goes to the batteries if they need charging. At sea we can see solar generating 20A, but only 10A going into the batteries. The rest is being used by the auto pilot, chart plotters etc.

420w of solar will certainly feed all small loads on board, leaving the domestic bank full for use as the sun sets. The upshot is a lower level of discharge which Stu discusses above.

Whilst multiple panels would be nice, like everyone I suspect there is a budget here, so a single 420w, decent MPPT and some re-wiring will produce really good results or 'bang for buck' if you like.

Pete

[rbyham]

My Honda is a basic 2000i. Very surprised how easily even on econ mode eit handles compressor cycling. Might be something in thee Webasto circuitry that helps. I do not use a soft start of any kind. Also I am extremely careful with CO conccerns.

[Ardbeg]

OK I am not an electricity expert. I have 2011 Catalina 375. Installed 2x 240W kyoceras when boat new. Run Parallel to 2 golf cart batteries. Changed batteries for first time in 2022. I have never touched the solar set up since new. I have 1500 W inverter. I have full set instruments incl Radar. TV, fridge and separate freezer ( Read beer fridge). I am on Lake Ontario. All lighting is LED. Never had to plug in unless a woman on board with hair dryer. Never had problems. I agree 2 panels better than 1 for shadow issues.
PS leave system on in winter to keep charge in batteries.

[Goodxcharly]

I own a 36’ Catalina too, MaluLani. Livaboard. I’m Assessing my current system of 2 100 watt flex panels and 1 80 watt portable, flexible panel. 4-100 amp 6 volt batteries.
The current system does pretty good with sun. Up to 7 days with no asist brings the batteries down to 12.1 bolts.
That is charging a Engel freezer. Adler Barber refrigeration plus misc.
I was thinking of adding 2 more 100 watts or might just use my Honda 2200 and the boats charging system. Run the Honda every 3 or 4 days which would also give me hot water.

Just some thoughts.

[cottonsail]

This is our system. 2- 250 watt Sanyo panels, 8 T-105 batteries, (6 for the house, 2 for starting) and Outback controller. This runs our entire boat with full sunshine. My entire setup cost $1126. + batteries.

[Nicholson58]

Originally Posted by GILow

Absolutely a bad idea to have carbon monoxide producing devices on boats if you can avoid it.

Such as the main engine? Get a fault in the exhaust circuit and you will be sucking CO. BTW, self amalgamating repair tape can get you to a chandler when your 3” wet exhaust hose splits.

Many Caribbean cruisers pack a Honda or other portable gen-sets. They run on deck in open air. The universal plea is please add a decent muffler or sound house.

[Nicholson58]

Originally Posted by rbyham

So I own a Catalina 36 ——-

Thanks in advance for any help from thihs knowledgeable group.

An excellent source for off grid living. A lot about lithium but also solar and charging.

https://marinehowto.com/lifepo4-batteries-on-boats/

There must be some good flex panels. One of our cruisers added flex to a lot of deck on his Shipman 63, with an all electric galley.

Do a lot of digging as you take your crash thesis study on the subject before committing to a lot of stuff.


We have about 1 kW of solar running on an MPPT controller. Big gen-set came with the boat. All alternators have Balmar external charge controllers. Batteries is LiFePo 710 Ah at 24 volts including house and start charged in parallel. Bogart battery monitors in addition to the BMS furnished along with the Blue Heron batteries. Refrigeration is 24 volts, both freezer and fridge. Water maker is 24 volts. We consume about 130 Ah daily.

[Juice13]

RV and van dwellers seem to have similar power usage to “basic” cruising boats. They’ve figured this out already. (Thanks Will Prowse!)

DC to DC charger with built in MPPT. Balances alternator and solar charging to maximize solar. Keeps Starter battery and House battery bank separate.

I adapted this setup but kept the 1-2-Both switch for a little more flexibility. Let’s you put Lithium on the house bank without messing with your alternator.

https://www.mobile-solarpower.com/si...-charging.html


We just yesterday motored 3.5 hours and saw a whopping 7 amps from the alternator (AtomicFour) and 4 amps from the 100W flexible panel.

Again, size your solar and alternator and battery AH higher if you want more capacity.

[sailingharry]

Originally Posted by Franziska

Your engine produces carbon monoxide, too. The exhaust takes care of it.

While you are technically correct, for all practical matters a diesel engine does not produce carbon monoxide in meaningful quantities. You will not find a reported case in any searching online. Unlike a gasoline engine which runs on a stoichiometric mixture of fuel and air (which invariably ends up a little shy on the air) a diesel engine runs with a massive surplus of air. Although for cars, and I think for modern gasoline power boats, the catalytic converter has all but solved the problem there as well.

Regardless, for $30 you can buy a fire/CO detector at Home Depot. Good for any potential diesel, stove, heater, or neighboring powerboat issues.

[sailingharry]

Originally Posted by Pete7

If the 420w LG panels are still available and have a recent date on them that would be nice.

If you are weekend sailing, you do not need lots of kit. However a Victron 100/30 MPPT with blue tooth would be a nice fit.

Pete

Pete,

I see you recommending the 100/30 as a nice match for the 420W panel.

I have just received a pair of 400W bifacial. I am intending to run each on a separate controller. I have been horribly conflicted on what controller to use, and the conflicting recommendations here just keeps me going. [emoji16]

On even number days, I'm ready to buy 100/30. I'm pretty convinced that the loss of power will be minimal. Only when the panel is in peak sun with peak bifacial gain and battery voltage down a ways.

But the following morning, I wake up with nightmares about leaving 5 or 10 amps on the table with the battery at 50% state of charge, a scorching Sun reflecting off a glassy ocean, and my water maker hungry for more. And I think the extra $100 each for a 100/50 is a no-brainer.

I'm wondering if you can share your thoughts on the 100/30 for a 420W panel.

[Notus]

There is a lot of good info here for a beginner.

[FlyingScot]

Originally Posted by sailingharry

Pete,

I see you recommending the 100/30 as a nice match for the 420W panel.

I have just received a pair of 400W bifacial. I am intending to run each on a separate controller. I have been horribly conflicted on what controller to use, and the conflicting recommendations here just keeps me going. [emoji16]

On even number days, I'm ready to buy 100/30. I'm pretty convinced that the loss of power will be minimal. Only when the panel is in peak sun with peak bifacial gain and battery voltage down a ways.

But the following morning, I wake up with nightmares about leaving 5 or 10 amps on the table with the battery at 50% state of charge, a scorching Sun reflecting off a glassy ocean, and my water maker hungry for more. And I think the extra $100 each for a 100/50 is a no-brainer.

I'm wondering if you can share your thoughts on the 100/30 for a 420W panel.

We have 5 x 435Wp LG Bifacials hooked to 5 x 100/50 MPPTs.

The extra $100 is only one time. The power gains are for years.

[Nicholson58]

My theory on the MPPT is oversize a bit. Electronics running at a comfortable margin don’t overheat, probably last longer. The next iteration of panel with higher output is then not a problem.

[mjscottinnc]

2 - Canadian Solar, 36 volt 315 watt panels, 2 - 200 a/h 12 volt separate banks, 2 - Mppt chargers, custom charge controller with manual override controls. Charge controller can connect the solar panels in series or parallel, connect to either battery bank with the configured panels ( 2 to one, 1 to each) based on each banks state of charge. Manual controls override the controller. When I cruise I live on the boat 6 months on - 6 months off, I haven’t plugged in for over 5 years.

[sailingharry]

Originally Posted by FlyingScot

We have 5 x 435Wp LG Bifacials hooked to 5 x 100/50 MPPTs.



The extra $100 is only one time. The power gains are for years.

So, how often do you see >30A from these controllers? Actually, since your panels are 10% larger than mine, it would be good to know how often you see >33A. That's when the extra oomph pays off.