Solar panel array for bow deck

[jms28]

Hi,

I'm looking to fit my motorboat w a powerful solar panel array on the bow deck. Here a few data points around my requirements:

• Total area available is 190x130 - I'm looking to maximize W and Amp, so the more I can get covered the merrier!
• Boat is permanently located in Greece and is primarily used for a few weeks during the summer months only (--> longevity!)
• Solar panels are intended to charge house + starter batteries, including during winter storage to maintain voltage
• Batteries in use currently are AGM deep cycle and I might upgrade to solar specific ones for the house circuit. But lithium-ion is currently not a consideration
• For charging I'm favouring Victron, as most other components I have currently are Victron and I am very happy with quality and usability

Based on the above requirements which (combination) of solar panels would you recommend? I like the flush cable management from Sunbeam and have had good experience with German Solara till date. Over how many panels would you recommend distributing the capacity? Better to have as few as possible or rather distribute over 3 or 4 panels?

Many thanks in advance

 

[wingcommander]

Interested in what are solar specific batteries.? .. genuine question
If not lithium (edit)

 

[Sea Change]

With that space available, you could fit a single domestic rooftop panel which will throw out 500w or so and cost less than £100.

 

[jms28]

Sorry, should have added: *must* be sturdy and slim walk-on panels as the space will also serve as sun lounger once in a while.

Re solar specific: found AGM batteries (allegedly) optimized for solar charging but not sure if this is just marketing. Might just stick to good quality deep cycle AGM but lithium is currently not an option.

 

[wingcommander]

Sorry, should have added: *must* be sturdy and slim walk-on panels as the space will also serve as sun lounger once in a while.

Re solar specific: found AGM batteries (allegedly) optimized for solar charging but not sure if this is just marketing. Might just stick to good quality deep cycle AGM but lithium is currently not an option.

Yes an attempt at wool pulling me thinks. As far as I have understood, lithium will accept the fastest charge, though not good to be kept 100%. Next is your AGMs and then your good ole toppable uppable Trojan types . Not sure where the gell type sits,though would be interested in more expert opinion.
Its a subject that's of interest as I do like to keep my fridge operating, and with temperatures climbing ime always battery monitoring

 

[Sea Change]

Sorry, should have added: *must* be sturdy and slim walk-on panels as the space will also serve as sun lounger once in a while.

Re solar specific: found AGM batteries (allegedly) optimized for solar charging but not sure if this is just marketing. Might just stick to good quality deep cycle AGM but lithium is currently not an option.

Apologies for the question but why are you ruling out lithium? If it's on cost grounds you may be working from incomplete information, especially as you've mentioned that your existing equipment is Victron and therefore very likely to be compatible.

 

[jms28]

Apologies for the question but why are you ruling out lithium? If it's on cost grounds you may be working from incomplete information, especially as you've mentioned that your existing equipment is Victron and therefore very likely to be compatible.

Safety reasons mainly. Got enough risks to hedge on my boat, don't need any more Plus I do have a Jackery solar generator which has a lithium battery inside. AGM deep cycle does the job for now.

But back to my Q: any thoughts/ recommendations re which solar panels and how many?

Thks

 

[blush2]

Sorry, should have added: *must* be sturdy and slim walk-on panels as the space will also serve as sun lounger once in a while.

Re solar specific: found AGM batteries (allegedly) optimized for solar charging but not sure if this is just marketing. Might just stick to good quality deep cycle AGM but lithium is currently not an option.

Solar panels get very hot, I wouldn't want to walk or lounge on them

 

[[70521]]

Re solar specific: found AGM batteries (allegedly) optimized for solar charging but not sure if this is just marketing. Might just stick to good quality deep cycle AGM but lithium is currently not an option.

Batteries have no idea where electrons came from so can't be optimized for direct current with a tan.

 

[PaulRainbow]

Sorry, should have added: *must* be sturdy and slim walk-on panels as the space will also serve as sun lounger once in a while.

Re solar specific: found AGM batteries (allegedly) optimized for solar charging but not sure if this is just marketing. Might just stick to good quality deep cycle AGM but lithium is currently not an option.

100% nonsense.

 

[PetiteFleur]

Presumably you are considering flexible panels not solidake sure they are ETFE which are better. I've used Platonic Universe on my boat and are pleased with them. I've used Index Marine for the deck seals as they are torpedo shaped, low profile and take two cables and available in different colours. Fit as many panels as possible in the space available.

 

[Graham376]

Interested in what are solar specific batteries.? .. genuine question
If not lithium (edit)

I bought some a few years ago, supposedly specifically for solar use. They lasted about 3 years, way shorter than current Trojans. Exide Classic Enersol Solar Batteries for solar application

 

[jms28]

100% nonsense.

Batteries have no idea where electrons came from so can't be optimized for direct current with a tan.

I bought some a few years ago, supposedly specifically for solar use. They lasted about 3 years, way shorter than current Trojans. Exide Classic Enersol Solar Batteries for solar application

Thanks for the input, I will surely consider this when selcting my next pair of house batteries (next year presumably).

Solar panels get very hot, I wouldn't want to walk or lounge on them

The idea is to either cover that space w a lounger before it gets hot or use for charging, depending on the plans for the day.

Presumably you are considering flexible panels not solidake sure they are ETFE which are better. I've used Platonic Universe on my boat and are pleased with them. I've used Index Marine for the deck seals as they are torpedo shaped, low profile and take two cables and available in different colours. Fit as many panels as possible in the space available.

Thks, will check these out as well. Project isn't due before early-2026 but gathering ideas and planning atm. Still undecided between two larger VS 3-4 smaller panels and the associated pros and cons from a electrical pov. Any thoughts on this anyone?

Thank you

 

[simonfraser]

As far as I understand any type of old fashioned wet batteries will need topping up, E.G. Trojan
I’d not want to leave those on charge for months without being able to check them
Stick with AGM

 

[Graham376]

As far as I understand any type of old fashioned wet batteries will need topping up, E.G. Trojan
I’d not want to leave those on charge for months without being able to check them
Stick with AGM

My Trojans, flooded la, stay on charge for up to 3 months when we come back to UK. I just make sure they're well topped up and turn Smartsolar controller down from 14.82v (normal absorption) to 14.4v. They float at 13.5v. On return, they may need a drop of water but not much and are then in service again for 4 or 5 months. They're 5-6 years old now and still fine.

 

[jms28]

Yes, AGM in any case for me. Batteries currently not the concern, rather the best solar panel array configuration Still undecided between two larger VS 3-4 smaller panels and the associated pros and cons from a electrical pov. Any thoughts on this anyone?

 

[Daverw]

Not sure what fire risk you are referring to with Lifepo4, sounds like your mean lithium iron which is not what you would be using

 

[jms28]

Not sure what fire risk you are referring to with Lifepo4, sounds like your mean lithium iron which is not what you would be using

Tbh I haven't investigated this much further in detail, but I read in the RYA magazine about quite a few boat fires in the past few years due to lithium batteries... Human error w/o doubt a major factor, but this put me off quite a bit tbh. As said, enough risks to manage as is. But pls pls pls let's not go OT too much: as stated several times, this thread is first-and-foremost about solar panels NOT batteries

 

[Sea Change]

Not sure what fire risk you are referring to with Lifepo4, sounds like your mean lithium iron which is not what you would be using

Lithium iron *is* LiFePO4.
(Typo?)
It's one subset of lithium ion chemistry. A very safe one that is suitable for marine use.

If the OP is concerned about safety with lithium batteries, I will leave it those with more time and patience to explain why that's not an issue.

 

[Sea Change]

Tbh I haven't investigated this much further in detail, but I read in the RYA magazine about quite a few boat fires in the past few years due to lithium batteries... Human error w/o doubt a major factor, but this put me off quite a bit tbh. As said, enough risks to manage as is. But pls pls pls let's not go OT too much: as stated several times, this thread is first-and-foremost about solar panels NOT batteries

Ok, I'll bite.
Lithium batteries come in different flavours.
The most dangerous are those in cheap consumer electronics like toothbrushes. Poor or absent management systems, poor build quality. Cheap scooters are notorious, just add badly built but with a bigger battery pack.
Power tools, laptops, tablets and phones all use dangerous volatile lithium chemistries, but they tend to be better designed and built and rarely cause trouble.

The above are the cause of almost every battery fire you will have heard of.

LiFePO4, otherwise known as lithium iron, or LFP, is a different sort of beast with much more benign characteristics. It's very hard to get these batteries in to any sort of thermal runaway. Look up videos of people deliberately throwing them on a bonfire or stabbing them with a pick.
A properly designed and installed LFP system on a boat will have the correct systems in place to protect it from any kind of failure that you are likely to encounter, and will if anything be safer than a lead acid system.