solar panel

Juggenaut · Veteran Member

solar panel

yobarr · Guru

Juggenaut wrote:
a simple question, will a 149watt fixed solar panel be enough to charge 2 100amp hr batteries?

No.You will need 300 watt plus.I use 190 watt for 90AH Lithium in my car,and 1700 watts for 540AH Lithium in van.

-- Edited by yobarr on Saturday 13th of October 2018 08:51:43 AM

-- Edited by yobarr on Saturday 13th of October 2018 08:55:17 AM

Jaahn · Guru

Juggenaut wrote:
a simple question, will a 149watt fixed solar panel be enough to charge 2 100amp hr batteries?

Hi smile

Simple answer; NO

Jaahn

Possum3 · Guru

It will if - you leave it charging for a couple of days, certainly not if battery is being used for anything.

Mike Harding · Guru

150W of panel - if you have good sun (Qld) they'll probably operate
at 85% efficiency for (say) seven hours a day.

150 x 0.85 = ~130W

Regulator/charger efficiency is around 80% to 90%, call it 90%.

130W x 0.9 = 117W at the battery for an average 14.2 charging voltage.

117 / 14V2 = 8.2 amps

8.2 amps x 7 hours = (call it) 58Ah per day.

----

You now need to look at your power consumption:
If you run a TV for three hours and the TV consumes 2A at 12V you
will use (3 x 2 = 6) 6Ah.

Do the above for all your appliances and if they exceed 58Ah you are
in trouble.

In reality you won't get 58Ah every day; cloudy days, tree shade and
time of year will reduce that daily average.

I suspect you will need 300W or more of solar.

rockylizard · Guru

Gday...

To paraphrase Mike - no.

Unless you use very little power overnight, and never camp on overcast/rainy days.

Cheers - John

Warren-Pat_01 · Guru

Juggernaut,
Check the appliances that you normally run - record the power they consume & the time you run them. Consider you location too (we get a lot more sun & skin cancers) than my brother in NE Victoria.

NOTE - a flat mounted panel on your van will NOT give you 150w!! It could be down to 125w or less in full sun.

Have a look at www.campertrailers.org/solar_spreadsheet.htm - you may find similar data on this forum too.

yobarr · Guru

Warren-Pat_01 wrote:
Juggernaut,
Check the appliances that you normally run - record the power they consume & the time you run them. Consider you location too (we get a lot more sun & skin cancers) than my brother in NE Victoria.

NOTE - a flat mounted panel on your van will NOT give you 150w!! It could be down to 125w or less in full sun.

Have a look at www.campertrailers.org/solar_spreadsheet.htm - you may find similar data on this forum too.

Agreed that a flat panel wont average the same production every day,but the losses are only 10%.During summer,the losses are nil,because no matter what angle the panel is on,it still will get sunlight for the same number of hours per day.The sun rises in the East,goes straight over the top of the van or whatever,and sets in the West.In winter,it drops closer to the horizon,so direct sunlight hours on a flat panel are fewer.The average loss is 10%.But you will need,as suggested,minimum 300 watts of panels.And a Lithium battery is a WAY better option.Just saying.Cheers

Juggenaut · Veteran Member

thanks everyone, I suspected that would be the case.

Jaahn · Guru

yobarr wrote:
Agreed that a flat panel wont average the same production every day,but the losses are only 10%.During summer,the losses are nil,because no matter what angle the panel is on,it still will get sunlight for the same number of hours per day.The sun rises in the East,goes straight over the top of the van or whatever,and sets in the West.In winter,it drops closer to the horizon,so direct sunlight hours on a flat panel are fewer.The average loss is 10%.But you will need,as suggested,minimum 300 watts of panels.And a Lithium battery is a WAY better option.Just saying.Cheers

Hi yobarr smile

I disagree about the loss being only 10%. That would be the best outcome IMHO and in the north of Australia. At the worst more like the 30% loss and average 20% depending on how far south you are.

Just put more panels up there to make it up. hmm

Jaahn

-- Edited by Jaahn on Saturday 13th of October 2018 04:11:47 PM

yobarr · Guru

Jaahn wrote:
yobarr wrote:
Agreed that a flat panel wont average the same production every day,but the losses are only 10%.During summer,the losses are nil,because no matter what angle the panel is on,it still will get sunlight for the same number of hours per day.The sun rises in the East,goes straight over the top of the van or whatever,and sets in the West.In winter,it drops closer to the horizon,so direct sunlight hours on a flat panel are fewer.The average loss is 10%.But you will need,as suggested,minimum 300 watts of panels.And a Lithium battery is a WAY better option.Just saying.Cheers
Hi yobarr
I disagree about the loss being only 10%. That would be the best outcome IMHO and in the north of Australia. At the worst more like the 30% loss and average 20% depending on how far south you are.
Just put more panels up there to make it up.
Jaahn

-- Edited by Jaahn on Saturday 13th of October 2018 04:11:47 PM

Hi John...you obviously are entitled to disagree! Ive given up arguing the point with people,and the OP is welcome to either take my thoughts on board,or ignore them.However,I do agree that he should put up more panels....I have more tgan 1700 watts on the van.Keeps the sun off the roof so I dont have to use the AC so much,although I can easily run it,or the heater, 24/7 off my batteries.Thanks for your contribution.Cheers

-- Edited by yobarr on Saturday 13th of October 2018 04:30:56 PM

Izabarack · Guru

No. Start with a rule-of-thumb of twice the Ah number of the battery bank and go from there.

Iza

Mike Harding · Guru

Izabarack wrote:
No. Start with a rule-of-thumb of twice the Ah number of the battery bank and go from there.

Not a bad "rule of thumb" I suspect.

Dickodownunder · Guru

Mike Harding wrote:
Izabarack wrote:
No. Start with a rule-of-thumb of twice the Ah number of the battery bank and go from there.
Not a bad "rule of thumb" I suspect.

Yes,

That is exactly what the tech that fitted up my solar recommended for me when in SA. and it works very well.

Juggenaut · Veteran Member

Beautiful all you contributers, thanks a lot. Gavin

Hylife · Guru

Just to provide some balanced opinions, my answer is "Quite possibly YES", BUT,,,,

It all depends on how much you have taken OUT of your batteries as to how much you need to put back IN.

If you only use 20 amps each day then a 150 watt panel will do quite nicely thank you.

So unless you first work out what you will use each day/night, then really any NO or YES answer is quite frankly, pointless.

My feeling are thus:-
Add as many solar panels as you can fit on your roof. If you can fit 3 or 4 panels, do it!
Why? Because when you are having solar installed the biggest cost is the labour, not the parts.
Panels cost about $1 per watt and a modern 150 watt panel only weighs about 10kg.
More panels means the installer will simply use heavier wire and a larger controller, other than that, the electrical installation work is pretty much the same.
So long as you have enough battery reserves without stressing them too low, then more solar equals a faster recharge rate, even on overcast days.

yobarr · Guru

Hylife wrote:
Just to provide some balanced opinions, my answer is "Quite possibly YES", BUT,,,,

It all depends on how much you have taken OUT of your batteries as to how much you need to put back IN.

If you only use 20 amps each day then a 150 watt panel will do quite nicely thank you.

So unless you first work out what you will use each day/night, then really any NO or YES answer is quite frankly, pointless.

My feeling are thus:-
Add as many solar panels as you can fit on your roof. If you can fit 3 or 4 panels, do it!
Why? Because when you are having solar installed the biggest cost is the labour, not the parts.
Panels cost about $1 per watt and a modern 150 watt panel only weighs about 10kg.
More panels means the installer will simply use heavier wire and a larger controller, other than that, the electrical installation work is pretty much the same.
So long as you have enough battery reserves without stressing them too low, then more solar equals a faster recharge rate, even on overcast days.

Using a 150 watt panel to charge 2x100AH batteries would be akin to going to Bathurst in a Volkswagen!

Peter_n_Margaret · Guru

Juggenaut wrote:
a simple question, will a 149watt fixed solar panel be enough to charge 2 100amp hr batteries?

Not a simple question.

A bit like asking if 2 bank accounts will let you pay your bills better than one bank account.

Depends how much money you want to take out compared with how much you put in.

Yes, the 149W panel will keep the 2 100Ah batteries charged, providing you use less power than the solar panel produces.

Cheers,

Peter

Jaahn · Guru

Juggenaut wrote:
a simple question, will a 149watt fixed solar panel be enough to charge 2 100amp hr batteries?

Hi smile

Yes the problem with the "simple" question is just this ; it is not a simple question and so expecting a simple answer is not reasonable. cry

Several posters have given the simple answer from their experience and observations, NO. But we all know that is not a full answer, but some people will not accept a more complex answer than that because they think all 'technical stuff' is too complicated. hmm Well guess what, it is, get over it smile

The correct answer to the question above is: -------wait for it --------, coming -------, read the Solar sub forum in the Techies' Corner, yourself, and get the answers already given lots of times before. biggrin

I only write this to point newbies in that direction for their own edification !!

cheers Jaahn

-- Edited by Jaahn on Tuesday 16th of October 2018 08:27:28 AM