Which solar panels?

#1
I’ve a solar panel already fitted on the roof of my van ( - 🙄 sorry I don’t know the wattage but on a sunny day I’m registering 2Amps), would it matter what size 2nd panel I fit ?
As important- what make/ brand do you consider the best both in terms of reliability, output & value?
 

Edina

Administrator
#3
If you are going to link the panels, I think they need to be the same voltage. I've had panels from Alpha Batteries and Bimble Solar, no problems with either
 


#4
Vic
We fitted phototronic universe panels 100 watts each! However as all know I do not do the (dark art) I do believe there’s something about the output of the panels re what your connecting it to re not to much going in!! Hopefully someone much more qualified will come along and explain
 

Edina

Administrator
#5
Here's an article that explains different ways of adding panels, and the pros and cons.
LINK
 


#6
Thanks Edina for the link, I read it but will have to read it several times before the fog lifts 😲 - if my existing panel gives me 2 Amps (full sun), does that mean 2 same size panels will produce 4 Amps ?
 


wildebus

Full Member
#7
Thanks Edina for the link, I read it but will have to read it several times before the fog lifts 😲 - if my existing panel gives me 2 Amps (full sun), does that mean 2 same size panels will produce 4 Amps ?
Basic Rule is:
Connect in Series - Double the Voltage, Current stays the same
Connect in Parallel - Double the Current, Voltage stays the same
That is going INTO the Solar Controller

Coming OUT OF the Solar Controller, the end result is the same for either way - Same Voltage, twice the Current.

(there are benefits of doing it either way, but that is a different conversation :) )
 
#8
It’s double the amps I want but still 12v - so parallel is the way 👍 (🙄?)
 

wildebus

Full Member
#9
It’s double the amps I want but still 12v - so parallel is the way 👍 (🙄?)
If you want doubkle the amps coming into controller, yes.

But into the Battery it is the same - if you have an MPPT controller, it will convert the greater voltage to greater current - that is one of the key benefits of MPPT over PWM.


example:

a 12V Panel is actually 20V Max (so a 100W Panel may deliver 5A at 20V ==> P=IV = Power = Current x Voltage)
(may sound strange but 12V panels are NOT 12V. similar to a 12V Battery is only 12V when it is flat)

so two 100W Panels in series = 200W ==> (20V +20V) x 5A
5A at 40V into Controller becomes 15A at 13V out the controller

two 100W Panels in parallel = 200W ==> 20V x (5A +5A)
10A at 20V into the Controller again becomes 15A at 13V out of the controller

(which is best way depends on the controller - they have maximum currents, voltages etc)
 


#10
Ahh sh*t - just as i thought I’d got it clear in my brain cell you throw a spanner in the works, I’ll have to go back to the drawing board 😩
 
#11
All I can say without Listerdiesel (Peter) I would’ve been lost when it comes to solar!!
 
#12
Ha - I’m floundering! I’m looking at the vast range of MPPT controllers 🥺
 
Top