Solar System Setup

Help...I'm going to setup a solar panel system eg. folding 240w solar panel through to a 230ah or 280ah agm deep cycle battery via a 300w pure sine wave inverter this to charge small appliances dvd player phone ipod/i pad, batteries, etc. All with 30% added came to 30AH usage daily this is without the inverter running, (standby usage 0.5A) i just want to go bigger in system so i have double power in reserve. 1 or maybe 2 Appliances maybe charge @ one time max 2hrs, 3 x daily-maximum.
1 of the Batteries above will replace excisting batteries which my campervan lights run off. I have a 3 way fridge but it only runs on gas for performance. Basically can both inverters run off the same battery via solar panels if 12v not connect to vehicle or not @ all? is my system to big or too small? hope somebody can help....

Regards DAVID.
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Reply By: ExplorOz - David & Michelle - Monday, Jul 22, 2013 at 19:24

Monday, Jul 22, 2013 at 19:24
David,

Sounds big to me. I have just come back from a trip and have for many years run the following:
1 x folding 100watt panel (55watt each but warranted 45w/panel at 17.2V)
1 x 120AH AGM Battery
1 x 300Watt Sine Wave Inverter

The AGM is connected in dual battery mode in the vehicle so will charge from Alternator when moving using a Redarc Smart Solenoid.

I recharge almost every day - lights, batteries, iPods, iPads, Phones and a whole load of stuff on 12V and also some days run laptop and camera battery charges on the inverter. We have an Engel fridge connected full time, vehicle mounted UHF radio (on most of the day), iPhone cradle and phone on most of the day. I also use the inverter a fair bit each day in short burst to grind my coffee beans (truly this can be a number of times - love my caffeine). On our recent trip I did not move the vehicle for 2 weeks and we still had a full battery each day reading 13.5V (after a disconnect of solar panel) each day. I have also run this set-up for over 3 days without the solar panel.

It depends on the outside temp for the fridge but on this trip most days were mid to high twenties and on the gauge at connected to the fridge it was much hotter as the fridge seems to always find the sun.

The system you have specified is heaps and if you can carry it and use it then go for it the 240w panel would be large I expect - what are the dimensions of this? Are you based in a car, camper or van? Can you angle the panels to the sun a few times per day or will they be fixed in place?

David
David (DM) & Michelle (MM)
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Follow Up By: David W28 - Tuesday, Jul 23, 2013 at 00:06

Tuesday, Jul 23, 2013 at 00:06
Thankyou DM & MM for your reply, this system is based on a campervan for 12v lights and charging small appliances as stated 30ah daily + inverters ampH. campervan has a three-way fridge runs only on gas don't run it on 12v, (don't run gas when travelling). We camp between 3 days and up to 20 days. I'm querying if i can connect the 300w inverter to battery in which the excisting campervan inverter is connected too which runs a 20amp fuse. 240w panels are 1100mmx1700mm opened, can get the 160w s-p which are approx 1100 x 1150. What AH does your 300w inverter run @ if ran for a day? hope this is more helpfull.

Cheers David.
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Follow Up By: ExplorOz - David & Michelle - Tuesday, Jul 23, 2013 at 10:47

Tuesday, Jul 23, 2013 at 10:47
David,
Firstly the answer to running two inverters from the one battery is YES. You can connect both inverters to a single battery no problems - run a separate cable and fuse for the new inverter. The inverters can be both or singly one at any time. The inverter power usage is based on what is plugged in to the 240V socket, so small power devices like camera charges draw very little - it is impossible to quote a number for the power without knowing the load you intend to run. Basic maths of P (power) = V (voltage) * I (current) is the first function to look at so a 200W load on 240V is a .83 Amp draw at 240V move to the 12V side (ignoring conversion loss in the inverter) to source this level or power with 100% efficiency would require 20 times the current at 12V so approximately 16.6Amps at 12V.

Your panels at 240W will deliver at best and assuming 100% of the rated output (which you will never get), perfect sun angle and no losses in the controllers 13.9Amps at 17.2V.

So if you run a 200W load all day (which is unlikely) and have perfect 100% full sun all day (also unlikely) your 240W panels will not keep up with this level of load. Factor losses, sun angle, conversions and reality and you will be lucky to see around 50-60% of the panel power available so you could be struggling to run a 100W load all day. There are so many variables, it is not a clear case of yes or no.

The answer is to go as big as you can fit and afford/justify.

Have a look at the Solar Power article I will link to this thread for further information.

David
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Always working not enough travelling!

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