How much solar do you have?

Kelpie said:
In practice, you run out of daylight hours when trying to charge lead acid batteries from solar. The much higher charge rate of lithium means that every watt of solar actually produces a watt of charging power.
Geem is using a rough approximation to get the, valid, point across
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Oh I'm sorry I don't belong to 'gang' ....
 
Refueler said:
Good ... explained. As I said - resistance related. Stemar caught on as well ...

But many who are not so genn'd up on batterys may misunderstand, :eek: think they really get 660W for 440W ....
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It's only partly to do with resistance. Lithium has circa 20% better charge acceptance rate than lead but the biggest difference is not spending time in float, wasting potential solar that you never harvest
 
geem said:
It's only partly to do with resistance. Lithium has circa 20% better charge acceptance rate than lead but the biggest difference is not spending time in float, wasting potential solar that you never harvest
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Why did you have to then go and spoil it by this ??? You were finally doing so well ... Oh well ...
 
You guys are making me feel like I use too much power. I have 1100 watts in two 550w panels, only 600Ah house, Gel, so really 250-300Ah. Need more, but I am waiting for Lithium. I am on an island so need to get to a continent to buy them there...

It charges great, I can almost run my banks out overnight if I leave the starlink on with everything else, but I try not to do that.

Looking forward to getting Lithium, hoping for a drop-in for my 6 house 100Ah batteries for simplicity. Should make it perfect.
 
The most desirable situation is to generate more solar energy than you can use. This would result in hitting regulation most days no matter what battery type you use.
 
noelex said:
The most desirable situation is to generate more solar energy than you can use. This would result in hitting regulation most days no matter what battery type you use.
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Not if it means buying a million bucks worth of catamaran to have enough space for the solar panels. Surely better to have a way to suck more sun out of what you have on the boat you have? Unless you have a spare million bucks, but then why on earth would you be hanging out here?
 
Slahm said:
You guys are making me feel like I use too much power. I have 1100 watts in two 550w panels, only 600Ah house, Gel, so really 250-300Ah. Need more, but I am waiting for Lithium. I am on an island so need to get to a continent to buy them there...

It charges great, I can almost run my banks out overnight if I leave the starlink on with everything else, but I try not to do that.

Looking forward to getting Lithium, hoping for a drop-in for my 6 house 100Ah batteries for simplicity. Should make it perfect.
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Ideally you want a pair of lithium batteries to replace your existing bank. Multiples beyond two can can problematic with balancing between batteries. . Make sure you lithium battery has active, not passive balancing. Don't buy cheap.
 
noelex said:
The most desirable situation is to generate more solar energy than you can use. This would result in hitting regulation most days no matter what battery type you use.
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Not really necessary with lithium but yes, if you use lead, sitting lead batteries on float is good but a waste of good solar with lithium batteries. May as well make some ice or do the laundry 🙂. You don't need to get to 100% charged
 
lustyd said:
Not if it means buying a million bucks worth of catamaran to have enough space for the solar panels. Surely better to have a way to suck more sun out of what you have on the boat you have? Unless you have a spare million bucks, but then why on earth would you be hanging out here?
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That is the crux ... making best of what is there to mount to ... without creating a hemmed in difficult to live with setup. Its fine for those who only cruise to have bimini with panels on .. stern arches etc. etc. - but the boat and its use will have a direct effect on how many and what size panels fitted. That's before you get into what batterys / capacity you are wanting to feed to.

Pal of mine with his 31 - wanted solar ... scrolled online till he hit wattage he wanted ... bought and when delivered realised ... WOW where am I going to fit it !
He laughed at my small 20W panel clipped to pushpit rail - until he tried to sort his oversized purchase !!

Like many things in life - its a compromise.
 
lustyd said:
Not if it means buying a million bucks worth of catamaran to have enough space for the solar panels. Surely better to have a way to suck more sun out of what you have on the boat you have? Unless you have a spare million bucks, but then why on earth would you be hanging out here?
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The size of system is largely irrelevant. As I indicated in post #31, I have cruised with both very small solar systems (by today’s standards) and reasonably large systems.

What is true in all cases is that if you are consistently using all the solar energy you are generating and are only very occasionally hitting regulation your system is unlikely to be successful without outside energy input from time to time, such as a generator or shore power. In addition if you are using all the energy you can generate most of the time there is no leeway to enable you to move to an area, or a season, with slightly poorer solar insolation.

if you want to manage on solar energy alone a healthy system will hitting regulation frequently in most situations.
 
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noelex said:
The size of system is largely irrelevant. As I indicated in post #31, I have cruised with both very small solar systems (by today’s standards) and reasonably large systems.

What is true in all cases is that if you are consistently using all the solar energy you are generating and are only very occasionally hitting regulation your system is unlikely to be successful without outside energy input from time to time, such as a generator or shore power.
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But apart from serious offshore people - isn't that situation most are in ? That solar is not quite enough in total - but is supplemental to other power forms whether from engine / shore or other ? To extend life on board between power sources ?
 
Refueler said:
But apart from serious offshore people - isn't that situation most are in ? That solar is not quite enough in total - but is supplemental to other power forms whether from engine / shore or other ? To extend life on board between power sources ?
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There is nothing wrong with setting up the boat like this where solar does not provide enough energy, but while common it is not ideal in my view. It is much nicer not to have start a generator, divert to a marina, or run the main engine unnecessarily to generate energy.

This is quite achievable for many boats with modern equipment. In many cases it can be done without missing out on most of the luxuries and without spending a fortune, but it does take planning and careful system design.

Times have moved on from the days when the only option was solar energy suppling part of a yachts energy needs. These days it can be the primary or even only source of power , although there will generally be at least a small contribution from the alternator when the engine is needed for propulsion,
 
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noelex said:
There is nothing wrong with setting up the boat like this where solar does not provide enough energy, but it is preferable to not have start a generator, divert to a marina, or run the main engine unnecessarily to generate energy.

This is quite achievable for many boats with modern equipment. In many cases it can be done without missing out on most of the luxuries and without spending a fortune, but it does take planning and careful system design.

Times have moved on from the days when the only option was solar energy suppling part of a yachts energy needs. These days it can be the primary or even only source of power , although there will generally be at least a small contribution from the alternator when the engine is needed for propulsion,
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That's true up to a point. Liveaboards tend to go to places with abundant sun (sweeping generalisation...). For those in Northern latitudes solar alone is less likely to provide year round reliability, particularly if heating is wanted.

That said, this is an interesting thread and is making me think before I consider replacing any bits of my system.
 
noelex said:
There is nothing wrong with setting up the boat like this where solar does not provide enough energy, but while common it is not ideal in my view. It is much nicer not to have start a generator, divert to a marina, or run the main engine unnecessarily to generate energy.

This is quite achievable for many boats with modern equipment. In many cases it can be done without missing out on most of the luxuries and without spending a fortune, but it does take planning and careful system design.

Times have moved on from the days when the only option was solar energy suppling part of a yachts energy needs. These days it can be the primary or even only source of power , although there will generally be at least a small contribution from the alternator when the engine is needed for propulsion,
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I realise that times have moved on ... cells convert solar to electricity at higher rates than before ... panels can be flexible and mounted in so many more locations than before ...

But lets not lose sight of boaters usual use of their boat ...

My latest boat - 38ft - you'd think that it would be easy to mount more than enough solar to not need shore power ... but the boat is not destined for a cruiser only life ... its a Cruiser Racer ... so last thing I want is a bimini / arch etc. ....

If it was not such a design - then yes - I would be looking to add more solar
 
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