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Solar to battery to tv, fan etc

melodie

Mar 1, 2018
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hi went out and bought a 300watt solar panel, hooked it up to a 1500 watt inverter, then to a 135 amp deep cycle hybrid, start and cycle, to power the 12v tv (I think 40 watt 3a] fan 50 watt- how long will this run and how long { hours}does the solar have to drip feed the battery to be fully charged again-{ full sun Australia} cheers and should I buy more batteries- 135 amp if I want this set up to keep them going 16 hours a day - how many more batteries?
 

kellys_eye

Jun 25, 2010
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A 300W panel - assuming working to its full capacity and is a 12V panel - will deliver 25A to the battery and it would take the battery around 6 hours to charge fully, delivering 150Ahr to the batteries (more than they can hold....) over that period.

Running the TV and fan for 16 hours will consume 16 x 7 (= 112Ahr) so your consumption is less than the capacity therefore assuming 6 hours of sunlight you will never run out of charge.

Of course, taking the various losses into account (no system is 100% efficient) these figures will be reduced somewhat. The inverter will only be around 85% efficient, the solar panels might only be 70% efficient (might not get constant sunlight either) and your batteries certainly can't be used to their full capacity repeatedly without causing them some harm (depends on the quality).

Personally I'd always use DOUBLE the battery capacity that you calculate for normal use - this places much less strain on the system as a whole and allows for various interruptions and efficiency losses.
 

melodie

Mar 1, 2018
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thanks for replying so I just buy another 135 amp?- its a AGM 12 v [absorbed glass matt} 34 kg- $300- read somewhere that it needs to be a certain weight to be a true cyclic?? and keep that charged and rotate them? getting constant light- queensland, - should I buy a bigger inverter.? I deliberately bought smaller so I didn't blow shit up- I bought a 4.8 kva generator runs at 4.2- for the fridge and freezer , in case of power blackouts [cyclone season] but I want to make it good enough so I can take it camping as a stand alone system - what should be next on my shopping list? I figured all this out on my own and bought it and put it together on my own but am bad at the math of it,- thinking I want to live off grid soon but be mobile- just a girl who wants to go fishing- permanently- thanks in advance
 

melodie

Mar 1, 2018
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A 300W panel - assuming working to its full capacity and is a 12V panel - will deliver 25A to the battery and it would take the battery around 6 hours to charge fully, delivering 150Ahr to the batteries (more than they can hold....) over that period.

Running the TV and fan for 16 hours will consume 16 x 7 (= 112Ahr) so your consumption is less than the capacity therefore assuming 6 hours of sunlight you will never run out of charge.

Of course, taking the various losses into account (no system is 100% efficient) these figures will be reduced somewhat. The inverter will only be around 85% efficient, the solar panels might only be 70% efficient (might not get constant sunlight either) and your batteries certainly can't be used to their full capacity repeatedly without causing them some harm (depends on the quality).

Personally I'd always use DOUBLE the battery capacity that you calculate for normal use - this places much less strain on the system as a whole and allows for various interruptions and efficiency losses.
please read the post below,.....
 

kellys_eye

Jun 25, 2010
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Mobile/portable? A system the size you describe isn't what I'd call portable!!!

Whatever inverter/generator you get the power output will depend entirely on the load, not the generator output itself and having a decent margin for output (say +50%) is always a good idea.

4.8kVA seems a bit excessive for a fridge/freezer combo though.... got the specifications for those devices?

Get the extra battery and wire it in parallel with the existing one - that's all that's needed. If the battery is truly 'deep cycle' (and AGM tends to be) then in NORMAL USE you won't do any damage but, like all batteries of whatever chemistry, taking care of them makes them last longer and you know they aren't cheap to replace.....

I'd carry a mix of technologies to cover all eventualities - solar (with batteries) and portable generator(s) with fuel (of course!). It takes seconds to start a petrol genny and power equipment - setting up a solar system could take 'hours' and best left for when you know you're going to be stationary for an appreciable length of time.

We live remotely (Scotland) and can power the whole house using two portable 900W inverter-generators (petrol generator with true sinewave output) if we need to - and that includes chest freezers!
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Jan 21, 2010
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We live remotely (Scotland) and can power the whole house using two portable 900W inverter-generators (petrol generator with true sinewave output) if we need to - and that includes chest freezers!

But it's so cold there that you can open the chest freezers to warm your house, right? :-D
 

kellys_eye

Jun 25, 2010
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Not really - a common misconception.

Where we live we're close to the coast where the warm Atlantic currents keep the local environment a lot warmer than you'd expect. There are some gardens in the area that have palm trees and other exotica!

Our biggest issue is the damp atmosphere - we've had some years where you'd think there wasn't a single day without rain of some sort! But, right now, we're in a rare Easterly snow event with -5C overnight (although the in-laws who live further inland get -15C) and snow on the ground - equally rare.

I used to live near to Newcastle and anyone that knows of that areas local reputation will know that it's starting to get cold enough for the girls to start wearing long-sleeve t-shirts instead of their usual bare midriff versions...... almost.
 
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