Ctek + Smartpass = solar

[Trotter]

According to the manual, the Ctek will handle 300 w of solar input.
If I was to fit a 360 w panel. Would this exceed the Ctek. Bearing in mind that, the 360w* panel would only produce anything like 360w in perfect laboratory conditions,and those conditions would not be found on the roof of a Fiat.
I either getting ahead of myself, or is it wishful thinking?
* Not measured roof area available yet. Maximum panel might be 320w

 

[Derekoak]

According to the manual, the Ctek will handle 300 w of solar input.
If I was to fit a 360 w panel. Would this exceed the Ctek. Bearing in mind that, the 360w* panel would only produce anything like 360w in perfect laboratory conditions,and those conditions would not be found on the roof of a Fiat.
I either getting ahead of myself, or is it wishful thinking?
* Not measured roof area available yet. Maximum panel might be 320w

What if you went to Morocco and parked tilted on a steep south facing slope. Would you go over 20 amp input? Maybe parked infront of a south facing white wall.

 

[Trotter]

What if you went to Morocco and parked tilted on a steep south facing slope. Would you go over 20 amp input? Maybe parked infront of a south facing white wall.

Pretty unlikely then

 

[exwindsurfer]

According to the manual, the Ctek will handle 300 w of solar input.
If I was to fit a 360 w panel. Would this exceed the Ctek. Bearing in mind that, the 360w* panel would only produce anything like 360w in perfect laboratory conditions,and those conditions would not be found on the roof of a Fiat.
I either getting ahead of myself, or is it wishful thinking?
* Not measured roof area available yet. Maximum panel might be 320w

One day in February in Moffat my panels where collecting 417watts of solar so you don’t need to be in a lab lolol.

 

[Nabsim]

If it’s like my Votronic Del it just disregards anything it can’t use. I think Phil or Dave did say how/why when I first did it but I have had 300W panels going through 250W controller for about two years now. And yes I have seen maximum in the U.K. but not that often when I am looking at it.
Ask Phil or Dave

 

[Admin]

The extra power will be fine. Just make sure you buy an 18v panel as the CTEK has a lower input voltage max 23v

 

[Trotter]

The extra power will be fine. Just make sure you buy an 18v panel as the CTEK has a lower input voltage max 23v

Among other things, this is not something I took into account.
Is this the
1, Maximum power voltage?
Or
2, Open circuit voltage?
Or,
3. Ask you what panel I should buy?

 

[mistericeman]

Among other things, this is not something I took into account.
Is this the
1, Maximum power voltage?
Or
2, Open circuit voltage?
Or,
3. Ask you what panel I should buy?

Yup I fell foul of the max input on the Cetek too.... My 400w bifacial I bought from Bimble was beyond what the Ctek could handle so I had to change plans and bought a Ring Rscdc 30 instead to cope with the voltage the panel outputs

 

[wildebus]

The extra power will be fine. Just make sure you buy an 18v panel as the CTEK has a lower input voltage max 23v

I was about to post this as well

Del, it is very unlikely you will find a single panel of 300W that is not around 40V input. The typical cross-over point between the "12V" panels (~20V) and "24V" panels (~40V) is the 180W-220W size. Below 180W most likely should be suitable, above 220W unlikely, between the two depends on panel spec.
A pair of 180W panels in parallel will give you your target 360W with near enough the same footprint as a single 360W panel

 

[Trotter]

I was about to post this as well

Del, it is very unlikely you will find a single panel of 300W that is not around 40V input. The typical cross-over point between the "12V" panels (~20V) and "24V" panels (~40V) is the 180W-220W size. Below 180W most likely should be suitable, above 220W unlikely, between the two depends on panel spec.
A pair of 180W panels in parallel will give you your target 360W with near enough the same footprint as a single 360W panel

So that's why folk put up multiple panels ? That sound you heard was the penny dropping.

 

[wildebus]

So that's why folk put up multiple panels ? That sound you heard was the penny dropping.

It is one of the possible reasons - many controllers are voltage limited (especially B2B/MPPT combos).

I prefer multiples for a multitude of other reasons ....
1) Managability - it is a lot easier to get say 3 100W panels on the roof than a single 300W panel
2) Relibility - if you have a mechanical/physical panel failure, it will only affect one panel out of a multiple array and you lose just partial output no matter how bad. Damage a single large panel and you likely loose all harvesting.
I also believe (no evidence, just my own logic) that the larger the panel, the less robust it is likely to be when subjected to the moving and shaking on a vehicle - big solar panels tend to be designed to be fitted securely to a static frame on a house roof or the like and that doesn't get bounced around constantly
3) Following on from 2), the cost and hassle of replacing a failed single panel of an array is a lot less than a single large panel
4) choice of connection - in parallel if your controller can't handle the voltage or you want to reduce shading problems; series if you want to eek out slightly more power; mix of the two to get benefits of both.
I have 6 panels on my campervan - 3 in parallel, another 3 in parallel and then those two sets joined in series.
5) footprint flexibility - easier to size up to get the most panel in the available space.
I have 3 90W panels to fit on the motorhome. choose that combination as it fills up the space available with around 20mm spare all around - if I went for a single panel I doubt I could find one of the right dimensions with that power output.

This is what I prefer anyway and I have always gone for multiples even with 75V and 100V controllers for all the reasons above.

 

[Trotter]

It is one of the possible reasons - many controllers are voltage limited (especially B2B/MPPT combos).

I prefer multiples for a multitude of other reasons ....
1) Managability - it is a lot easier to get say 3 100W panels on the roof than a single 300W panel
2) Relibility - if you have a mechanical/physical panel failure, it will only affect one panel out of a multiple array and you lose just partial output no matter how bad. Damage a single large panel and you likely loose all harvesting.
I also believe (no evidence, just my own logic) that the larger the panel, the less robust it is likely to be when subjected to the moving and shaking on a vehicle - big solar panels tend to be designed to be fitted securely to a static frame that doesn't get bounced around constantly
3) Following on from 2), the cost and hassle of replacing a failed single panel of an array is a lot less than a single large panel
4) choice of connection - in parallel if your controller can't handle the voltage or you want to reduce shading problems; series if you want to eek out slightly more power; mix of the two to get benefits of both.
I have 6 panels on my campervan - 3 in parallel, another 3 in parallel and then those two sets joined in series.
5) footprint flexibility - easier to size up to get the most panel in the available space.
I have 3 90W panels to fit on the motorhome. chose that combination as it fills up the space available with around 20mm spare all around - if I went for a single panel I doubt I could find one of the right dimensions with that power output.

This is what I prefer anyway and I have always gone for multiples even with 75V and 100V controllers for all the reasons above.

If I understand what you are saying correctly, to increase my harvesting capacity, all I need to do is add another 100w panel (or 2 ) to the two 100w panels I already have on the van. If the newer panels were in parallel to the older ones, any difference in efficiency wouldn't cause to much of a problem ?

 

[wildebus]

If I understand what you are saying correctly, to increase my harvesting capacity, all I need to do is add another 100w panel (or 2 ) to the two 100w panels I already have on the van. If the newer panels were in parallel to the older ones, any difference in efficiency wouldn't cause to much of a problem ?

If you have two 100W panels already, then I would absolutely look at getting one more matched one rather than taking them off and getting one big one.

As far as mixing panels goes, the basic rule of thumb is in parallel the voltage reverts to the lowest in the set and the current adds together; and in series, the current reverts to the lowest in the string and the voltage adds together.

So in your case you want to try and find a panel with the same Voc (Open Circuit Voltage) as the existing two. It wouldn't have to be a 100W panel either - you could go for a single 150W if you had the room to give you 350W potential (this is possible with Parallel but not with Series).
Go lower and you will loose some efficiency with the two you already have; Go higher and you will lose some efficiency with the one you are adding.
But the effect is fairly minimal as the voltages for "12V" panels tend to all be quite close together.

Something to be aware of however ... When you connect panels in parallel, you are keeping the voltage the same but upping the current sent to the controller. If you say add two more 100W panels, you have to be happy your cable from roof to controller can handle twice the current.
And the same applies with the cable from Controller to Battery (I know in your case that last point is covered easily, but it may be different for others reading this thread).

 

[Trotter]

If you have two 100W panels already, then I would absolutely look at getting one more matched one rather than taking them off and getting one big one.

As far as mixing panels goes, the basic rule of thumb is in parallel the voltage reverts to the lowest in the set and the current adds together; and in series, the current reverts to the lowest in the string and the voltage adds together.

So in your case you want to try and find a panel with the same Voc (Open Circuit Voltage) as the existing two.
Go lower and you will loose some efficiency with the two you already have; Go higher and you will lose some efficiency with the one you are adding.
But the effect is fairly minimal as the voltages for "12V" panels tend to all be quite close together.

Something to be aware of however ... When you connect panels in parallel, you are keeping the voltage the same but upping the current sent to the controller. If you say add two more 100W panels, you have to be happy your cable from roof to controller can handle twice the current.
And the same applies with the cable from Controller to Battery (I know in your case that last point is covered easily, but it may be different for others reading this thread).

All cables are the usual 6mm sq. From panel, through to Ctek. Then to batteries. 6mm sq all the way. Starter battery to Ctek, then onto leisure batteries and earth 22mm sq.

 

[wildebus]

All cables are the usual 6mm sq. From panel, through to Ctek. Then to batteries. 6mm sq all the way. Starter battery to Ctek, then onto leisure batteries and earth 22mm sq.

no issues with that cabling

(6mm2 is not quite the usual - it is the largest you tend to ever see )