solar panels portable

charles · Member

solar panels portable

TheHeaths · Guru

Charles,

it would help to know what you are running from the batteries, and the approximate draw each day to work out what you need to put back into the battery via your solar panel.

As an example, when free camping I can top up our 2 * 100 Ah batteries with 1 * 80 watt portable panel because we use very little 12 volt items.

You may need more, especially if you have a compressor fridge, or run a second fridge, or have any medical equipment.

in transit · Senior Member

We have a compressor fridge but no TV/DVD and draw about 55aH/day. We have recently chucked the solar controller that came with our 120W portable panels and now use the MPPT regulator in our Redarc DC-DC charger. When this was completed we did a solar-only test in the backyard starting with a warm 110L fridge. The weather was sunny, the panels were periodically rotated and after 3 days the two 125aH batteries were fully charged and the fridge very cold.

In a free camp situation we would have had some small drain from the LED lighting, and the water pump would have used some power.
The fridge was empty and the door was opened regularly.

If you write down how many amps all your electricity guzzling products use, multiply that by the number of hours they will be used/day, and then add up all the results, you will get a good idea of your usage. If you are not sure about this, an auto sparkie should be able to give you the answers.

How much you generate with the panels obviously depends on the rating (size) and the weather. But it also depends on the length of cable from the panels, how thick it is, whether the regulator is removed from the panels and located near the batteries, and whether the regulator is any good. And finally it also depends on whether you will diligently rotate the panels throughout the day to get maximum sun exposure.

Our plan B for bad weather is to run the motor and let the DC-DC charger help out, or spend a night in a CP. A generator is another backup.

oldtrack123 · Guru

Hi Charles
The Answer lies with how much you use daily [over 24Hrs]
You need to make a list of all the electrical items you use & how long they run for EACH 24hrs
Then check the wattage rating of each item & multiply that by the hours of running time for that item
Then Add up ALL those daily use figures
That will give you the daily Watthours of energy used
Divide that by 12 & it gives you the daily Amphours used
You must replace at least that, plus 10to 20% EVERY day

The solar panels will, on bright sunny days & If Tracking the sun, give around :
Their rated WATTS divided by 17 then multiply that by hours they are in the bright sun equals the Amphrs most likely produced in that period.

BUT none of that takes into account the days when due to weather the panels may generate very little

Any thing that others post is simply what suits THEIR use!!!

-- Edited by oldtrack123 on Thursday 3rd of March 2016 05:04:13 PM

rockylizard · Guru

Gday...

As others have already stated Charles, it is very important to firstly know (or estimate) what your expected 24hour usage of 12V power would be.

I came across the attached spreadsheet some time ago (thanks to Richard Graylin). I found it quite handy to figure out what my estimated usage might be and then to determine how much solar and/or battery storage I needed.

Run some figures through the spreadsheet, and try a few different scenarios. It will help to give some idea on what you will - or may - need.

Cheers - John

PeterD · Guru

Another question - are you in Tasmania or up around Qld? The further south you go the larger the panels you need.