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Too much solar?


Jak
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HI all.   I suspect this is too general a question, but is there a rule of thumb between W of solar and AH of battery bank?

 

We have 3 x 95AH batteries and have 3 x 100w panels.  This seems to work well and suit our needs as hobby boaters.   I could add panels, but suspect it would be a waste as we already have what's needed to fill the batteries. 

 

I'd be interested to hear from others on the correlation between the two and when there's "too much" solar?  I know some of you have huge arrays (thinking of Peter Boat's 3.6KW here!!).

 

Cheers, Jak.

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6 minutes ago, Jak said:

HI all.   I suspect this is too general a question, but is there a rule of thumb between W of solar and AH of battery bank?

 

We have 3 x 95AH batteries and have 3 x 100w panels.  This seems to work well and suit our needs as hobby boaters.   I could add panels, but suspect it would be a waste as we already have what's needed to fill the batteries. 

 

I'd be interested to hear from others on the correlation between the two and when there's "too much" solar?  I know some of you have huge arrays (thinking of Peter Boat's 3.6KW here!!).

 

Cheers, Jak.

I have an electric drive Jak, so I do need that much solar, it makes life in the winter very easy, and in the summer the spare solar heats water via an immersion heater, so it works for me.

When I went cruising for 7 months 400 watts did me fine, allowing me to stop for days without running the engine [I had an Alde for hot water] thats my tuppenth worth

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Too much solar in mid summer could easily turn into not enough solar in the depths of winter. The controller will/should protect the batteries so it comes down to how much can you afford or, more likely, how much can you fit on the boat. As Peter says if you get surplus in the summer you can use it to heat water.

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1 hour ago, Jak said:

I'd be interested to hear from others on the correlation between the two and when there's "too much" solar? 

 

The thing about solar is no matter is no matter how much you have, it will virtually stop working in midwinter. So the more you have, the later in the year it stops working and the earlier in the following year it starts again.

 

So the concept of 'not enough solar' is the thing to consider, and this this depends on the extent of your winter use. 

 

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11 minutes ago, OldGoat said:

I'd spend your money on more batteries and larger capacity too.  Four 120 Ah seems to be the modal choice (amongst sensible folks any way)

I agree.  And we originally had 2 (knackered) x 110ah and replaced with the 3 x 95ah simply because they were smaller batteries and I could shoehorn them into the box (even then with some modifications).  I cannot see how to make space for more batteries.  It's quite tight under there ☹️

 

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2 minutes ago, Jak said:

Evidence added...

IMG_1231.JPG

You seem to have a lot of wires 'tapped' into the battery bank.

 

What does the Black, Red and Blue wire do on the nearest yellow battery ?

That 'red' wire is a very unsafe 'connection' (I use the term loosely) as it appears to be just 'jammed' into the battery clamp. Not good practice.

 

If that is to either put 'leccy in, or take 'leccy out you should attach one wire to the opposite ends of the battery bank to balance the load thru the whole bank.

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Hmmm.  I need to check where the blue wire goes as I honestly can't remember.  Yes, the black and red wires come from the solar controller and are due to be connected properly (and to either end of the bank) - they are just 'jammed' in to the clamps on the nearest yellow battery.  I'd forgotten I left it like that.... 

 

  • Horror 1
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1 hour ago, Jak said:

Hmmm.  I need to check where the blue wire goes as I honestly can't remember.  Yes, the black and red wires come from the solar controller and are due to be connected properly (and to either end of the bank) - they are just 'jammed' in to the clamps on the nearest yellow battery.  I'd forgotten I left it like that.... 

 

Is it possible to remove the starter battery and mount it somewhere else and squeeze another domestic in that box?

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It depends. If a boat spends most of its time cruising in the day, then is used only in the evenings for living on, then solar isn't really needed since the engine will be easily able to do the lion's share of the required charging. This is the typical use of a hireboat.

 

And, if the boat's more for cruising than moored up; and you need the roof space (for example if its a bit shorter than average), then the panels could get in the way of eg mooring ropes or storage etc etc

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5 hours ago, bizzard said:

It'll be burning that bit of the sun out!!!    THE END IS NIGH!!!!!

oh dear!  that's a fallacy.

 

you can't burn a bit of the sun out.

 

what happens is that the stuff that has to fly from the sun, and is caught by your solar, saturates the ether along its route, until no more stuff can make the journey until the following day when the ether has had the chance to recharge.  

 

any fule nose that.   :rolleyes:

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3 hours ago, zenataomm said:

My concern is always that with the number of solar panels draping the rooves of boats there could be a drain on the sun.

That'd result in a brightness drop for us all.

I blame this bloke...

7AEBC412-C5F2-47C1-9786-7CD4D42D7FA5.jpeg.4cb9022e2819d8a5a846078b105fa3c4.jpeg

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Yup, it works well enough for what we need. I originally started the thread to see if there was a rule of thumb for solar (W) to battery’s (ah).  It’s been a very interesting thread, but the answer to my simplistic question seems to be a No. 

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21 hours ago, Alan de Enfield said:

What does the Black, Red and Blue wire do on the nearest yellow battery ?

 

 

Either the black, red, or blue wire disarms the bomb obviously, but which do you cut?

 

22 hours ago, bizzard said:

It'll be burning that bit of the sun out!!!    THE END IS NIGH!!!!!

Boaters with solar panels are very un-environmental, damaging the sun. Fortunately, most of us still have diesel engines and stoves burning fossil fuels, which are stored sunlight from millions of years ago, being put back in to the environment. This puts off the day when the sun goes out. The really evil boaters are the ones with all electric, solar powered boats.

 

Jen

Edited by Jen-in-Wellies
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12 minutes ago, Jen-in-Wellies said:

Either the black, red, or blue wire disarms the bomb obviously, but which do you cut?

 

Boaters with solar panels are very un-environmental, damaging the sun. Fortunately, most of us still have diesel engines and stoves burning fossil fuels, which are stored sunlight from millions of years ago, being put back in to the environment. This puts off the day when the sun goes out. The really evil boaters are the ones with all electric, solar powered boats.

 

Jen

And what are the ones with solar hot water? ?

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23 hours ago, OldGoat said:

I'd spend your money on more batteries and larger capacity too.  Four 120 Ah seems to be the modal choice (amongst sensible folks any way)

 

 

 

Incoming.....

As a liveaboard, approaching 6 years, I'd recommend considering the opposite of this advice. Depending on your power usage, of course. I use around 30ah/day (my fridge is gas). I had 2 x 110ah batteries unless I saw the light and went for just a single 105ah one (Trojan). This effectively gives a day and a half of usage but my 375w of solar gives me 100% of my needs between mid February and mid October. During the winter months I'll run my generator for an hour one day, 3 hours the next, usually, but sometimes my wind turbine cuts this right down.

 

Why go to the cost, not to mention hassle of replacing a higher number of batteries than you really need?      

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1 hour ago, Jen-in-Wellies said:

If you look very carefully you can see the shore line cable used to keep the batteries topped up when it is cloudy.

 

Jen

Doesnt it sail around the world constantly? its a very clever piece of work to be sure

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