Solar Panel Question-Help

[Flanders]

G'day Guys,

I'm inexperienced with solar, so forgive me if this is a stupid question

With the expanda I have ordered, it has the Jayco 90W solar kit and 105AMP battery included. I currently have a 120 watt solar kit (portable / foldable) with controller on it that I use on my Swan by just plugging in to the Anderson plug. (It's a mandrake solar set up for those that know of the company.)

In the new expanda, I will be running, the LED lights, 12 Volt LED TV (occasionally), the water pump of course, and maybe an Engel (but with the 150L fridge compared to the fridge in the Swan, may not need this). Also thinking of fitting an Inverter for the Coffee Machine (request of the Mrs.)

Would I be better to-

1. Take the regulator off the portable panels and fit to the expanda roof, pick up the wires of the existing panel to give me more capacity.

2. Sell the portable unit (I have someone that wants to buy it), and use the money to install a second battery. (would the 90watt panel, be enough to keep charge up?)

 

[Soaring]

Hi Flanders, I cant help, but am looking forward to some responses on this one. I have a similar issue

 

[ROnEM]

Flanders,

A long response follows.....

The advantage of the panels on your roof is that you will not have to carry/put out the folding panels.

The disadvantage of the roof mounted panels, is that if you have the van under some shade, this effects the roof panels, whereas the portable panels can be moved out of shadows. Also, portable panels can be facing the morning sun charging the battery/ies for your coffee machine.

The rule of thumb is to remember not to take the battery to below 80% charge - taking it below will shorten the battery life.

So, if you have a 100% charged 105AH battery, you want to draw now more than 21Amps from it without it being recharged by the solar panel/s.

Looking at your appliances, allow:
2 Amps for your LEDs,
5 Amps for your TV (if 60W then Watts = Volts X Amps, 60 = 12 x 5)
7 Amps Water pump
208 Amps (max) for a 2,500W inverter (2,500 = 12 x 208)

Then add up how long you think you will be running things off the battery. If you run the lights for 2 hours, then that is 2 Amp per Hours or 4 AH.

Don't forget to add things like phone charges, base/standby loads on inverters, tv, etc. A base/standby load is the power/amps brawn by the item even when you are not using it.

When you add this all up it might be:
Lights 3 hours = 6AH
TV 2 hours =10AH
Pump 15 min = 2AH
Coffee 10 min = 15AH (1000Watt coffee machine used for 10 mins a day)
Base/Standby = 2AH

Equals 35AH consumption per day....

So you need the solar panel/s to be able to recharge the battery with at least 35Amps throughout the day. However, as you lights, TV and Coffee are typically going to happen from sun down to sun up, this has the potential to draw your battery below the 80% mark, down to just above 65% (105-35 = 70A, 70A/105A = 67%) before the solar panel/s can start recharging. If you had 2 batteries fitted, this would only be drawing them to about 83% (210-35 = 175A, 175A/210A = 83%). This will be much better for optimlal battery life.

Regardless if you have 1 or 2 batteries, it is important you panel/s can produce enough amps to refill the battery.

Taking the average of some 90W solar panels, they produce a maximum of just over 5A. Based on this you would need 7 hours of optimlal solar panel performance to fully recharge you battery/ies. As a rule of thumb, for the southern states, assume 4 hours of sunshine at 80% efficiency. This would yield 16Amps (4hrs x 5W * 80%).
A 120 watt panel will produce about 6.5A, so using the same maths, yields 20.8A per day.

As you can see, the answers are "it all depends" on how much power you are using and how many hours of sun you get to recharge. This dictates the number of batteries and the size of your panels.

Persoanlly, I have a 200Watt 10.5Amp folding panel and 2 x 100AH batteries. We run all LEDs including a 4m LED strip on the outside of the van, watch some TV and I have a 2,500W inverter for the Coffee Machine for my wife. We also use it for toaster, microwave, etc. We do not try to use the Air Conditioner unless we have 240V power to the van. We were remote camping for 10 days and used everything happily with this set up - no issues. I did have solar pre-wired into the van. In the future, I am thinking of putting on some lightweight flexible panels - possibly 300-400 watt in total on the roof, but this is a long way off!

Hope this helps and my facts are right - happy to be corrected!

Cheers,

Rohan

 

[Flanders]

Cheers Rohan. Your explanation is great mate. I can now get my head around what I need to do. Thanks again

 

[Grover]

i have a waceo fridge freezer i keep an 240 watt solar panel on,150 litre fridge runs of gas and my 120 watt runs battery in van for lights ect,i camp for 4 weeks not a problem with this set up,its hard to run solar panel of van battery and waceo 240 watt might deo both but i purchased 120 watt first couldnt do both,so i got 240 watt

 

[brookes2622]

I have a 120w folding panel and am in the process of installing a 200w on the roof. I will be using both. I have an Anderson plug on the A-Frame that will connect directly to the battery so I will plug the folding panel into it when required. My view is that the permanent panel may not always be in the sun and the folding panel cannot be used on the move.

Best of both worlds by having my cake and eating it too.

 

[Flanders]

I've ended up ordering 2 batteries in the van and a 120 watt thin panel off my mate mandrake which I will sikaflex to the roof and hook up to the 90 watt. Hoping this should be enough. Will report back once I get the van and get set up.

 

[Xpandafan]

I've ended up ordering 2 batteries in the van and a 120 watt thin panel off my mate mandrake which I will sikaflex to the roof and hook up to the 90 watt. Hoping this should be enough. Will report back once I get the van and get set up.

Just remember you normally need to allow fir bit of air circulation under panel.

 

[Flanders]

Hi xpanafan. I believe with these thin film panels it is OK To sikaflex straight to The roof. This is the message from Steve at Mandrake Solar

White marine grade Sikaflex is the best - These panels don't need a space as​

the backing Is 2mm Aluminium sheet .. Just remember when you put the​

Sikaflex on to make sure you get as close To the edges as possible to​

prevent any air getting underneath and vibrating / lifting the panel .​

 

[Xpandafan]

Hi xpanafan. I believe with these thin film panels it is OK To sikaflex straight to The roof. This is the message from Steve at Mandrake Solar

White marine grade Sikaflex is the best - These panels don't need a space as​

the backing Is 2mm Aluminium sheet .. Just remember when you put the​

Sikaflex on to make sure you get as close To the edges as possible to​

prevent any air getting underneath and vibrating / lifting the panel .​

Great, just checking technology catching up and overtaking me, again.

 

[boots33]

technology catching up and overtaking me, again.

Yep ... know that feeling