solar opinions please

[waterdog]

Hi,

 

Anyone used this

 

http://www.ebay.co.uk/itm/100W-foldable-poly-solar-panel-kit-for-12V-battery-charger-camping-boat-2-50W-/181396231417?pt=UK_Gadgets&hash=item2a3c0ed4f9

 

Required to top up a 330ah leisure bank. Is it any good?

 

Thanks

 

 

 

 

 

[Bobbybass]

Hi,

 

Anyone used this

 

http://www.ebay.co.uk/itm/100W-foldable-poly-solar-panel-kit-for-12V-battery-charger-camping-boat-2-50W-/181396231417?pt=UK_Gadgets&hash=item2a3c0ed4f9

 

Required to top up a 330ah leisure bank. Is it any good?

 

Thanks

 

 

 

 

 

Bob's thoughts :

 

I don't 'think' it will do a huge amount..unless your power usage is very small..

 

It WILL do something....on a sunny day..maybe 5 amps.....and cut engine running a little....(when the sun is out )

Couldn't see it doing a lot more than that...and probably 3-4 amps on normal days...

 

BUT other people will come along...and add things..

[Grace and Favour]

If you want it to just top up your battery/s whilst you are away from the boat, then it would do that.

 

But I suspect that's all.

 

And the folding case assembly really isn't even suitable for that!

 

 

Are you wanting a PV supply to augment your daily usage, or something just to top-up when you're away from the boat?

[waterdog]

Thanks for the replies, its just to give a little bit extra charge to the domestic bank.

 

The boat is a share boat and we have been having issues with the batteries getting a bit low overnight, Main items on board are new shoreline 12v fridge, 3 to 4 hours dvd watching / internet - via laptop. No tv on board, and general things like phone charging radio etc. Lighting is a mix of different 12v units, possible upgrade to led might help! Does have an invertor but 240 use is minimal, vacuum on handover etc.

 

The engine is a bmc 1.8 with a 70a alternater which I believe is about the max the bmc can cope with. 3x 110ah domestic batteries.

 

Just want to put a bit more into the batteries especially on short cruising days and try to cut down on running the engine while moored in the evenings.

 

thanks

[matty40s]

You are asking an awful lot, especially as the sun goes down in the evenings.

[Alan de Enfield]

We dont have these panels but we do have a 100w system

 

This time of year we have 2 amps early morning and late afternoon and 5-7 amps from about 10am to 6pm. Our panels are laid flat on the roof, whilst with this kit you can slope them into the sun and get more.

 

We can go to bed with about 12.5 volts showing and by breakfast time the batteries are showing 12.8 - 13.0 volts (the extra 3 or 4 hours in the morning - from sun-up - top it up niceley)

 

Using

12v fridge 24/7

TV (30 watts) 5 hours per day

PC (40 watts) 4 or 5 hours per day

Occasional Deep fat fryer, hoover and toaster via the inverter

[waterdog]

You are asking an awful lot, especially as the sun goes down in the evenings.

lol

 

Now if someone could invent a solar panel that works at night, a lunarpanel perhaps

We dont have these panels but we do have a 100w system

 

This time of year we have 2 amps early morning and late afternoon and 5-7 amps from about 10am to 6pm. Our panels are laid flat on the roof, whilst with this kit you can slope them into the sun and get more.

 

We can go to bed with about 12.5 volts showing and by breakfast time the batteries are showing 12.8 - 13.0 volts (the extra 3 or 4 hours in the morning - from sun-up - top it up niceley)

 

Using

12v fridge 24/7

TV (30 watts) 5 hours per day

PC (40 watts) 4 or 5 hours per day

Occasional Deep fat fryer, hoover and toaster via the inverter

Thanks Alan, that sounds exactly like what we require.

[Alan de Enfield]

Just to add - our 'usage' is a little greater than the 'input' but only marginally. We can stay moored for 2 days/nights without having to run the engine, the 3rd day we are down to 12.1 / 12.2 volts.

 

The 100 watt system more than keeps the fridge going with the balance being supplied by the batteries (2 x 135 amp)

[MyLady]

Check the mountings! Unless you're moored north-south, the tilt won't do much good: it needs to be to the east in the morning and to the west in the evening (assuming the panels tilt side to side, hence the n-s mooring). Matty recommended two 165W panels from Bimble for us @ 95 quid each (and you need a controller too, whether with this bank or Bimble's). Ours is a 440Ahr bank and it definitely helps, especially when we're not aboard. I'd definitely check out a more powerful alternator though - if you're cruising, that will generate much more power during the middle of the day (unless you cruise 6am to 9am then moor until 6pm to maximise solar input).

 

Solar power is very useful when you are moored, but when you're moving, the alternator generates MUCH more power! Even a 50A one is 600W at 12V. A 100A one is twice that.

 

IMHO,

 

Roger

Edited June 2, 2014 by MyLady

[Pykebird]

No one has ever told me my bmc can't have a bigger alternator. I have now got a 95 amp one??

[Bobbybass]

We dont have these panels but we do have a 100w system

 

This time of year we have 2 amps early morning and late afternoon and 5-7 amps from about 10am to 6pm. Our panels are laid flat on the roof, whilst with this kit you can slope them into the sun and get more.

 

We can go to bed with about 12.5 volts showing and by breakfast time the batteries are showing 12.8 - 13.0 volts (the extra 3 or 4 hours in the morning - from sun-up - top it up niceley)

 

Using

12v fridge 24/7

TV (30 watts) 5 hours per day

PC (40 watts) 4 or 5 hours per day

Occasional Deep fat fryer, hoover and toaster via the inverter

 

Alan.....are you trying to say that with a fridge (5 amps usually when running)...30 watt TV x 5 hours = 15 amp..PC 20 amps..and the huge demand of a deep fat fryer...and toaster via inverter....that 2 amps for a few hours in the morning and maybe 5-7 amps will put all that back ?!

[matty40s]

Waterdog, to expand on previous, you will probably find that the solar will produce nothing at all when the boat is cruising as the alternator is pushing a large load into the battery bank so the solar thinks they are charged.

The only benefit would be April -Aug, waking up with batteries which are more charged than when you went to sleep, and they would keep a small charge coming in if you Moor up early.

[Alan de Enfield]

 

Alan.....are you trying to say that with a fridge (5 amps usually when running)...30 watt TV x 5 hours = 15 amp..PC 20 amps..and the huge demand of a deep fat fryer...and toaster via inverter....that 2 amps for a few hours in the morning and maybe 5-7 amps will put all that back ?!

 

The fridge is about 35 aH per day.

I reckon that the 100w solar is putting in an average of 4a over (say) 14 hours so about 55aH

 

The solar supplies enough for the Fridge, pumps, lights & phone charging

 

The deepfat fryer is 900 watts and when it is used it takes 18 minutes from 'cold' to cooked chips. So approx 1/3 of 90 amps = 30 amps

 

The toaster is 800 watts and when used it takes 12 minutes to produce 4 slices of toast from 'cold', so 1/4 of 80 amps = 20 amps

 

TV and PC = 35 amps.

 

Total usage from the bateries (ie not supplied by solar) 85 amps if I use the fryer and toaster, if I dont use the fryer (which we often dont use) then the usage is 55 amps.

 

Two days usage = 110 amps

 

I have 2 x 135 leaisure batteries and the very rarely get below 12.2 volts.

 

Am I doing somethng wrong with my maths ?

All I know is it works for us, we use what we need to use and we dont get flat batteries.

 

(Hoovering is an irregular exercise.)

NB - according to the clamp-meter the fridge draws 4.0 amps when running, I've made an assumption it will be running for about 33% of the time. This could well be an over estimation as I think it barely ever kicks-in during the night

[waterdog]

No one has ever told me my bmc can't have a bigger alternator. I have now got a 95 amp one??

Something to do with the maximum load a v belt can carry before it wears out prematurely, a few threads on here mention it.

 

 

Waterdog, to expand on previous, you will probably find that the solar will produce nothing at all when the boat is cruising as the alternator is pushing a large load into the battery bank so the solar thinks they are charged.

The only benefit would be April -Aug, waking up with batteries which are more charged than when you went to sleep, and they would keep a small charge coming in if you Moor up early.

Sorry Matty, I thought you were taking the P!!! earlier.

Seriously though, getting a little extra charge via the solar in the evening after cruising can only help and with it being a share boat most people cruise daytime and moor up about 4 to 6pm. Also some of our members only do very short days or may decide to stop in one place for a couple of days so surely it will be a benefit then and help reduce the time the engine needs to be on. Or am I still missing something.

 

Alan / Roger , thanks for the info, very useful.

 

Cheers

[bottle]

Solar panels need sunshine, well bright light.

 

The output of the solar panels as is the alternator, controlled by the batteries.

 

Yes solar may help but it will have to be a big array.

 

Today, we set of with the batteries at 68% SOC ran for over two hours with long runs at 'full speed' (1350 rpm, fast for us) moored up at 13:30 hrs, batteries at 92% SOC, now at 87% SOC, have boiled kettle twice (1 Kw), fridge and freezer running, charged one laptop.

 

80 amp, 24v alternator.

 

We have 400 watts of solar, giving a maximum of 16 amps into 24v, very rarely see the 16 amps, lack of sun and batteries generally in the 60 to 95% SOC.

 

 

I'm rambling but it may be useful

[Paul C]

 

The fridge is about 35 aH per day.

I reckon that the 100w solar is putting in an average of 4a over (say) 14 hours so about 55aH

 

The solar supplies enough for the Fridge, pumps, lights & phone charging

 

The deepfat fryer is 900 watts and when it is used it takes 18 minutes from 'cold' to cooked chips. So approx 1/3 of 90 amps = 30 amps

 

The toaster is 800 watts and when used it takes 12 minutes to produce 4 slices of toast from 'cold', so 1/4 of 80 amps = 20 amps

 

TV and PC = 35 amps.

 

Total usage from the bateries (ie not supplied by solar) 85 amps if I use the fryer and toaster, if I dont use the fryer (which we often dont use) then the usage is 55 amps.

 

Two days usage = 110 amps

 

I have 2 x 135 leaisure batteries and the very rarely get below 12.2 volts.

 

Am I doing somethng wrong with my maths ?

All I know is it works for us, we use what we need to use and we dont get flat batteries.

 

(Hoovering is an irregular exercise.)

NB - according to the clamp-meter the fridge draws 4.0 amps when running, I've made an assumption it will be running for about 33% of the time. This could well be an over estimation as I think it barely ever kicks-in during the night

 

You've forgotten inverter losses and lighting. And you've assumed that the capacity of your 135Ah batteries is 135Ah - it won't be unless brand new, and even then may not be!

[Alan de Enfield]

 

You've forgotten inverter losses and lighting. And you've assumed that the capacity of your 135Ah batteries is 135Ah - it won't be unless brand new, and even then may not be!

 

Inverter losses are more than taken care of (eg by taking 900w as 90 amps instead of an 'actual' 75 amps)

Batteries are virtually new

 

You may have missed this :

 

The solar supplies enough for the Fridge, pumps, lights & phone charging

 

At this time of year the only lights are 1x LED in the lounge and 1x LED in the bedroom - both for only an odd hour or two, if used at all - insignificant amperage

[Paul C]

Have you already got the solar stuff, or are you thinking of buying it?

 

If the batteries are full or near-full, solar controller will effectively "float" charge the batteries with 0.5-1amp going in. If they're not full, and the sun is shining, they'll put in as much as possible - if its sunny, then that will be around 8 amps, if its not then maybe 1-2. Is your 4 amp average figure based on the batteries being flat or charged; or the weather being intermittently sunny? I think you also need to consider when the electrical items are used, and what the deepest discharge might be (which will be just before solar power input > power draw, which typically occurs around 6-7am). Remember, you've watched a bit of telly, used the lights, etc in the evening and when you went to bed, the fridge kept running. If its a cold/dark day, then you've used more lights and might have lit the stove --> fridge might be running more, within the warmed up cabin area.

 

It still leaves a lot of a shortfall, how are you putting that back in? Engine running? More solar? etc

[Alan de Enfield]

Paul C, on 02 Jun 2014 - 6:56 PM, said:Paul C, on 02 Jun 2014 - 6:56 PM, said:

Have you already got the solar stuff, or are you thinking of buying it?

 

If the batteries are full or near-full, solar controller will effectively "float" charge the batteries with 0.5-1amp going in. If they're not full, and the sun is shining, they'll put in as much as possible - if its sunny, then that will be around 8 amps, if its not then maybe 1-2. Is your 4 amp average figure based on the batteries being flat or charged; or the weather being intermittently sunny? I think you also need to consider when the electrical items are used, and what the deepest discharge might be (which will be just before solar power input > power draw, which typically occurs around 6-7am). Remember, you've watched a bit of telly, used the lights, etc in the evening and when you went to bed, the fridge kept running. If its a cold/dark day, then you've used more lights and might have lit the stove --> fridge might be running more, within the warmed up cabin area.

 

It still leaves a lot of a shortfall, how are you putting that back in? Engine running? More solar? etc

 

If the question is directed at me I already have solar (as I stated in post #6)

The batteries are normally fairly well charged on the 'first night' - mooring up at around tea-time, they will get a 'solar top-up' until dark.

 

Engine stopped at say 5pm - 4 hours of solar at 1 amp.

Our heavy usage is TV, PC and fridge.

Overnight the TV, PC and will have used approx 35 amps, the fridge will have used approx15 amps total used 50 amps less 4 amps (solar)

Usage 46 amps.

 

Solar starts at about 5 am (lets say 6 am) until 10 am producing average 2 amps, (8 amps produced)

Total taken from batteries now 46a - 8a = 38 amps,

 

Fridge from 6am until 5pm uses 20 amps - total out of the batteries now 38a - 20 a.

 

Solar producing average of 4 amps from 10am until 5pm = 28 amps

 

Total now out of batteries 20a - 28 a. = Battery 'gain' 8 amps.

 

Aditional usage : Toaster 20 AMPS.

 

From 5pm till 5pm the following day I have used 20-8 (12 amps)

 

The following day is a repeat, except that I do a load of chips - additional usage 30 amps.

 

Over two days the usage is 12+12+30 amps. = 54

 

I know what I mean - its not easy to explain but hopefully you can follow my logic.

 

I can only repeat it works for us, and we dont get the batteries below 50%. We are not really a large user.

Most 'cooking' is via gas oven

 

Edit - just had a look - volts at 13.36 solar putting in 0.5a (7:50pm)

Edited June 2, 2014 by Alan de Enfield