Advice needed RE Solar Panels

darragh97 · 17-08-2014 4:19pm #1

Hi all,

Looking in investing in a very small solar panel rig so i can hopefully save money on charging and running appliances (Lapotops, Phones, etc.....)

Aside from the obvious (the panels themselves), What will i need to get this up and running..

Having read through a number of forums on the subject there is a vast (solar) array of abbreviations and terminology which I am not familiar with, so simple language where possible is appreciated!

Capt'n Midnight · 17-08-2014 10:45pm

you won't save any money unless they are the only electrical devices and you can get rid of your ESB connection altogether and even then the main saving would be on the standing charge.

My phone has a 2.5Ah 4V (charged) battery. This is 10Wh.

If I had to fully charge it fully every day I'd use 3,650 Wh.

A year uses less than a unit of electricity, that's less than 20c.

Even over 5 years that's less than a euro.

If you have a old Nokia that can go a week on a charge then the cost saving are less.

Also unless you are at home during the day , you'd have to buy and charge a battery which could then charge your phone, so more costs.

Portable panels can be handy during the summer, but they are for convenience.

darragh97 · 18-08-2014 8:38pm

Sorry I wasnt clear Capt'n Midnight, what i meant to say is its for outdoor use, camping etc... my mistake

Capt'n Midnight · 18-08-2014 11:41pm

now it's the matter of batteries vs. solar , cost vs. weight

If you have a car, you can plug a €20 laptop charger into the cigarette lighter socket, but not too many times between driving else you might have a flat battery

if you are a light user and only going off grid for a weekend then carrying some spare laptop batteries might be cheaper and lighter than solar.

consider using a tablet instead of a laptop, longer life, needs less solar

19-08-2014 11:21pm

Capt'n Midnight wrote: »

if you are a light user and only going off grid for a weekend then carrying some spare laptop batteries might be cheaper and lighter than solar.

I can get 115Ah (@12v) of lead acid for the same price as 4.6Ah (@14v) of laptop Li-Ion.
Just an FYI...I know weight etc. might be more important issues

19-08-2014 11:25pm

Super small scale solar is into gimmicky chocolate tea pot territory. A few house alarm batteries might do. Charge them at home.

Capt'n Midnight · 20-08-2014 7:07pm

Sir Liamalot wrote: »

I can get 115Ah (@12v) of lead acid for the same price as 4.6Ah (@14v) of laptop Li-Ion.
Just an FYI...I know weight etc. might be more important issues

you need to get your laptop batteries elsewhere

But yes Lithium is lighter but maybe 10-20 times the price of lead acid

From an ecological point of view there is a big problem with batteries in that the the energy used to make them is comparable to the amount of energy they can store and release during their working lives. There's an argument that aluminium-air batteries would be better, single use but then you recycle them instead of recharging

but for low power usage the economics are different
https://www.aldi.ie/en/specialbuys/hurry-while-stocks-last/hurry-while-stocks-last/ps/p/professional-power-bankrugged-power-bank/

Aldi are doing 12Ah / 7.8 Ah USB chargers for twenty notes.
won't be enough for a laptop, but should keep an ebook reader / phone topped up all weekend or longer. You could recharge when in a coffee shop / pub.

You won't get much in the way of solar for that price because, like LED lights , the retail markup is insane compared to the production cost.

22-08-2014 10:59am

Capt'n Midnight wrote: »

you need to get your laptop batteries elsewhere

Yeah probably. I have 4, various sizes. and levels of usefulness. I don't use them anymore they're in storage at 40% DOD.
They're very inefficient to charge, especially when I charge a lead acid to charge a li-ion. Wastes nearly 50%.
The laptop batteries also struggle to deliver the "torque" needed for current hungry applications and the comp. slows to a crawl.
I get more cycles from lead acid too so the economics aren't so straight forward.

Capt'n Midnight wrote: »

From an ecological point of view there is a big problem with batteries in that the the energy used to make them is comparable to the amount of energy they can store and release during their working lives.

I see that argument a lot and stopped giving it credence.
Lead acid is wholly recyclable. Scrap value €0.50 per kilo.
Be that as it may and much as I like carbon dioxide negative devices it only seems to be a consideration of those who are already on the right track. Cars will never return O² to the atmosphere yet lots of people have them. H bombs return an abundance of energy compared to what they took to make but these are not useful. The simple fact of the matter is if you live on batteries you will naturally reduce your energy demand exponentially.

Capt'n Midnight wrote: »

Aldi are doing 12Ah / 7.8 Ah USB chargers for twenty notes.

These are neat little do-fers but don't expect to get your full Ah worth, charging a battery from a battery means that you get a reduced return of energy as the donor equalises in voltage with the receiver (unless there's fancified electronics involved like op. amps....which these probably have actually because they charge at 5v and output 5v).

If going down the solar road then don't pay more than €1.20 per watt on the panel and I'd say 40W mono-crystalline minimum for practicality. After than you need a solar regulator, a battery and a regulated (car) charger thingy for your devices.

22-08-2014 11:03am

Capt'n Midnight wrote: »

now it's the matter of batteries vs. solar

Solar plus batteries I'm afraid without the battery to voltage clamp the panel then the voltages are in the danger zone. :pac:
You wouldn't drive a car without a battery...for very long...same thing kinda.

Advice needed RE Solar Panels

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