Solar panels required

Ger08 · Senior Member

Solar panels required

swamp · Senior Member

Hi
160---200watts per 100-120ah battery
Why
AGM 100ah batt usable =50Ah

recharge time
Peak sun hours [PSH] 5.5 hrs in mainland ozzy [ for summer 6.5hrs and winter 4.5] [this 90%ozzy but not tazzy for 9 tenths of the year seasonal year ]
sun outside these hrs is unreliable to measure .

Electrical charge Losses roughly 20%
panel position
Panel angle
size of wire
controller type
controller efficiency
panels rarely produce there nominated output Real life is not a laboratory

200watt produce Approx 48ah in 5.5hrs
160watt produces approx. 38ah in 5.5rs

Mppt was not included in the above but will give u a bonus in charge upto 30% if the batteries are at least 25% or greater down in charge
Xtra sun hrs are not included either

PSH is 100% sun not 98% so ther probably is a little to be gained but as i said b4 unreliable

AJust to siut your conditions eg camp in warmer climates 160 / cooler 200watt per 100ah batt . Minimum

By having your batterries charged b4 lunch allows better for cloudy weather . This is an important bonus ..

Jaahn · Guru

Ger08 wrote:
Hi all,
I currently have 2 x 100 amp AGM batteries and a single 160 watt portable panel. We run a Waeco CFX fridge led lights and need to recharge phones, cameras, tablets and PCs, and Im trying to figure out if we need more or larger panels and would appreciate any advice in this area?

Hi Ger08 smile

In my opinion you would be better with at least double that or more. Depends on all those factors that swamp said. But the test of normally being up to float voltage by lunch time or soon after is a good one, as it allows for those bad days to be OK.

Any panels that have a MPV close to the same will be OK to run in parallel with the other ones and get a bigger PWM regulator and fit it close to the battery with decent sized wiring and some external plugs with decent wiring too. Probably better and easier to fit them on the roof in the long run. Just buy a couple of standard panels off ebay and some good wires there or jaycar or similar.

Also look at the other threads as there is discussion on lots of these things. There is a search function up the top in the blue bar under the adds. Use that too.

Jaahn

T1 Terry · Guru

What do you want to mount them on or do you want portable panels?

Roof mounted, the best possible total solar harvesting from a limited area needs smaller panels rather than large panels. This is because the smaller panels can fit in a spot where the larger panels won't fit without getting shaded. Shade on a panel only looses the output from that panel, so 3 x 60w panels would loose 60w and still have 120w available, a 200w panel would produce next to nothing if the shade is across any part of the panel. The down side is smaller panels are more expensive per watt than larger panels and there is more work involved in fitting them, but the end result is well worth the added cost.

If you want to stay with portable panels, you need to keep in mind the weight involved and wh

Ger08 · Senior Member

Thanks for all the responses - Im looking at portable panels

Tony Bev · Guru

I am not an electrician, so can only go by my own situation

In my opinion it depends on exactly how much power watts/amps you actually use

I have just recently changed from a gas fridge, to an upright 12 volt compressor fridge

I have 300 watt of roof solar panel, going through a 20 amp MPPT DC/DC charger, into 2 x 120 AH AGM batteries, (batteries are also charged when engine running)
I find that it is adequate for my power needs

A good friend has a 12 volt compressor chest fridge
He has 200 watt of roof solar panel, going through a MPPT solar regulator, into 2 x 120 AH AGM batteries (his batteries do not get charged by his engine)
He finds that it is adequate for his power needs

Ger08 · Senior Member

Thanks Ton