# Battery and Solar Systems



## sallytrafic (Jan 17, 2006)

Hi 

Last year I published a series of three articles on Solar systems in the Renault Traffic Motorhome Register magazine and on their Yahoo! group. Plus a diagram and an Excel spreadsheet to help with designing your own system.

I guess that quite a few people on this site are interested in Solar energy and with the larger vehicles there is more room for batteries and modules. So the 64$ question if there is the interest how do I publish them here?

By the way although retired a year or so I was a senior electrical engineer and project manager with Trinity House Lighthouse Service and have engineered solar projects on quite a few lighthouses and lightvessels as well as being their solar model 'expert'.

regards Frank


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## 88726 (May 9, 2005)

hi frank

could have used your input last year when i built mine , you can see my efforts in my picture album . biggest problem was finding suitable base boards and conductive adhesive at realistic prices . ive still got a few monocrystaline cells left over but theyre so difficult to solder i havent the heart to start again .


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## peejay (May 10, 2005)

Hi Frank,

I'm sure your articles will be most welcome, if you pm the boss - nukeadmin, i'm sure you could email them to him and he could convert them into a suitable format for entry onto the site.

pete.


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## sallytrafic (Jan 17, 2006)

Now published see main site front page

frank


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## autostratus (May 9, 2005)

A very welcome addition to the information on the site.
Thank for for putting it together.

I don't understand it all but I'm trying. 
It will have kept the Alzheimers away for a while if I succeed.


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## peedee (May 10, 2005)

A great article Frank, thanks for publishing it.

peedee


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## sallytrafic (Jan 17, 2006)

Thanks for your kind comments but it has only had three 'reads' and no one has voted for it


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## peedee (May 10, 2005)

Give it time, I haven't read all of it but I know it is there if I need it.

peedee


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## 96783 (Nov 23, 2005)

Not only have I read it but I've downloaded it as one of the most comprehensive (and understandable) articles on the subject which, for many of us, was previously shrouded in mystery. As a result I am about to purchase an alternator to battery charger from Sterling to make sure that my solar panels don't get caught out in winter conditions. I, for one, am a grateful reader, even if I was one of only 3. Mrs Thatcher may have been a lady who didn't understand the word "compromise" but for solar panels it is clearly an essential.


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## Ocsid (Dec 6, 2005)

I have read it; twice actually but thats no reflection on you its just that I take time to absorb things! 
Just one question if I may at the moment, can you comment on the two types of panel used? I note government department Central and Local use "Blue" units whereas many MHs use "Grey" types. Why please?


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## DABurleigh (May 9, 2005)

Frank - a very useful resource. I'm happy with my 85W Shell; during the summer months it is all I need, and other than the depths of winter it means I needn't bother connecting the van to hookup when I'm at home.

PhredC - let me know how you get on with the Sterling. Which model are you getting? I have pondered the 50A battery-to-battery charger but have yet to dive in.

So far I have only used mains hookup when the overnight temperature has been sub-zero, mainly for a silent oil-filled radiator. Trouble is, I like the autonomy of not "relying" on off-board facilities, but during the darker months I like my energy consumption, too, with satellite TV, eberspacher diesel heating (12V glow plugs) and halogen dimmable spots. Unless we are attending a rally/show we tend to take the van out each day, but I'd be a freer consumer of 12V if I knew I could put it back at a rate of ~30 amps, rather than my vehicle battery telling my alternator it's happy!

Dave


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## 96783 (Nov 23, 2005)

Hi Dave,

the 90A one, on the basis of charging up two 110Ah batteries. Its a bit pricey at over £200 and perhaps is overkill but I shall talk to the helpful people at Sterling before I make the order. I have to confess to taking a bit of a belt and braces approach as I approach late middle age.


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## sallytrafic (Jan 17, 2006)

[quote="Ocsid"Just one question if I may at the moment, can you comment on the two types of panel used? I note government department Central and Local use "Blue" units whereas many MHs use "Grey" types. Why please?[/quote]

Panels (modules) some in three basic flavours Monocrystaline - most expensive highest efficiency (16-18%), Polycrystalline (10-12%) and the cheapest Amorphous (5%). All are normally blue or sometimes grey. This is because they are trying to absorb all the sun light if they were successful then of course they would be matt black.

For aesthetic reasons they are now produced in a variety of colours but all are less efficient than the original blue or grey as in this quote about BP solar modules:

"they are available gold, magenta and steel blue. Colour variations are achieved by reflecting light from the surface of the cell, reducing the amount of light absorbed and therefore reducing the efficiencies to between 12-15% depending on the specific colour. This is in comparison to the original dark blue cells which achieve efficiencies between 16-18%."

I hope that answers your question I believe that blue is better than grey for efficiency as I bought literally 100's of top end marine modules and they were all blue suggesting that blue are best. - or at least most expensive!

Regards Frank


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## DABurleigh (May 9, 2005)

PhredC,

I think that is overkill, even literally so for your batteries if you don't set the Ah on the unit. For longevity a sound rule is not to charge at a rate greater than 1/5 of its capacity, 44A for your 2*110Ah. 

Check your alternator output, too. Mine is 110A and it wouldn't regularly have 90A spare to give!

The 50A unit should be fine. Even then they do the battery-to-battery one and alternator variants. Speak to Charles if you can.

Dave
"as I approach late middle age."
You're not getting to 80, are you?


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## sallytrafic (Jan 17, 2006)

DABurleigh said:


> For longevity a sound rule is not to charge at a rate greater than 1/5 of its capacity, Dave


Even thats high Dave. For routinely charging deep discharge lead acid or gel leisure batteries it is often recommended that you use the 3hr rate divided by 10. For example a battery quoted at 100Ahr at the 10hr rate might be 95 Ahr at the 3 hour rate and therefore the maximum charge should be 9.5A. Certainly that was the recommendation for batteries produced by Chloride.

Incidently the 100Hr rate for a battery might be as much as 1.4 times that quoted for the 3Hr rate, and the discharge time of our leisure batteries is hopefully closer to 100 hours than 3 hours. Some good news for a change.

regards Frank


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## DABurleigh (May 9, 2005)

Frank,

I wonder if that caution applies where you HAVE (too?) deeply discharged it?

A useful source I often quote, being a Victron fan/user, is this book:
http://www.victronenergy.com/upload/documents/ElectricityonBoard_rev8_july2004.pdf

Section 2.5.6 says "at most" 1/5 capacity.

Dave


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## sallytrafic (Jan 17, 2006)

Thanks Dave

I have an earlier version of the victron paper. We (Trinity House Lighthouse Service) put Vaders comments to some battery manufacturer's and they agreed 1/5 as an absolute max but only as an equalization charge or as part of a step charge regime, a lot of the time these batteries are being float charged or slow cycle charged. I personally wouldn't go above 1/10th unless the battery was temperature monitored. Trinity House decided to stay with 1/10th as we had had batteries which had lasted 40 plus years.

Regards

Frank


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## 96783 (Nov 23, 2005)

Thanks to both Dave and Frank for their helpful advice. I think that I'm now wiser, certainly older, and my apologies for the tardiness of the thanks. I'd lost the thread and probably the plot as well!

I will speak to the guy at Sterling before I actually make an order. When I'm parked up at home I'm always on mains supply so the problem will only arise when we're away wild camping.


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## Minerva (May 22, 2006)

Hi

Could someone point me in the right direction for sallytraffic's article on solar panels, I just can't find it
cheers 
Bill


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## DABurleigh (May 9, 2005)

Bill,

Earlier in this thread it refers to a link on the front page. It is way down the left-hand side, Guides - Solar power.

Dave


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## Minerva (May 22, 2006)

Hi Dave

Got it, thanks

Bill


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## putties (May 18, 2005)

Thank you sallytraffic

Putties


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