Different wattage power solar panel connection?

Owlhouse

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I am wanting to upgrade my solar capacity by installing a 200w panel to add to the existing 100w on my Burstner. I know I will have to replace the solar controller (the one that comes installed by Burstner is rubbish) but my question is - will I need an mttp controller for each panel, joining the outputs at a AMT12-2 or similar or will a suitable amperage one suffice by joining the panels in parallel then into an AMT12-2?
 
Controllers only start charging when the input voltage reaches a certain level (around 14v I think).

Wiring two panels in series increases the input voltage and so makes better use of lower sun conditions. But as mentioned, the current will be limited by the smaller one, reducing the potential 200w output.

You may be just as well just adding another 100w, or remove the old and fitting two bigger ones if there's room.

Or just wire them in parallel and hope for brighter days.
 
Owlhouse said:
I am wanting to upgrade my solar capacity by installing a 200w panel to add to the existing 100w on my Burstner. I know I will have to replace the solar controller (the one that comes installed by Burstner is rubbish) but my question is - will I need an mttp controller for each panel, joining the outputs at a AMT12-2 or similar or will a suitable amperage one suffice by joining the panels in parallel then into an AMT12-2?
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You have to quite careful when combining Solar Panels and you have not provided enough information to really give a good answer.

Basic rule is:
Connect in SERIES and you add the voltages, and the maximum current will be that of the lowest value (and the lowest value is not necessarily that of the smallest panel)
Connect in PARALLEL and you add the currents, and the maximum voltage is that of the lowest value (and again the lowest value is not necessarily that of the smallest panel)

A lot of controllers are "12V" controllers and cannot take panels in series without damaging them. So that is one consideration
When you get to a panel of 200W size, you need to check if it is a 12V panel or a 24V panel - that size is around the transition size between them.
If it WAS a 24V 200W panel and you connected in parallel to a 12V panel, you would instantly at least half the power of that 200W panel.
Probably be easiest to use a single MPPT controller, but you want to try and match as closely as possible the currents if going for Series, and the Voltages if going for parallel.
You can certainly mix different sizes if you want, as long as they are matched correctly. On my last van I had 4 x 100W panels and 2 x 40W panels. On my current motorhome I have a mix of 90W and 30W panels.


I am not sure where the AMT12-2 comes into the discussion? what is your reasoning behind bringing this into the solar panel connection question?
 
wildebus said:
You have to quite careful when combining Solar Panels and you have not provided enough information to really give a good answer.

Basic rule is:
Connect in SERIES and you add the voltages, and the maximum current will be that of the lowest value (and the lowest value is not necessarily that of the smallest panel)
Connect in PARALLEL and you add the currents, and the maximum voltage is that of the lowest value (and again the lowest value is not necessarily that of the smallest panel)

A lot of controllers are "12V" controllers and cannot take panels in series without damaging them. So that is one consideration
When you get to a panel of 200W size, you need to check if it is a 12V panel or a 24V panel - that size is around the transition size between them.
If it WAS a 24V 200W panel and you connected in parallel to a 12V panel, you would instantly at least half the power of that 200W panel.
Probably be easiest to use a single MPPT controller, but you want to try and match as closely as possible the currents if going for Series, and the Voltages if going for parallel.
You can certainly mix different sizes if you want, as long as they are matched correctly. On my last van I had 4 x 100W panels and 2 x 40W panels. On my current motorhome I have a mix of 90W and 30W panels.


I am not sure where the AMT12-2 comes into the discussion? what is your reasoning behind bringing this into the solar panel connection question?
Click to expand...
Thanks for the answers. It would be a 12v 200w panel added to a 12v 100w existing panel. They would be in parallel as I want the charge current increase. The AMT12-2 was there just as another connection option in case two controllers were needed and would be used for the LB/SB charging.
 
Owlhouse said:
Thanks for the answers. It would be a 12v 200w panel added to a 12v 100w existing panel. They would be in parallel as I want the charge current increase. The AMT12-2 was there just as another connection option in case two controllers were needed and would be used for the LB/SB charging.
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right,
So parallel is the way to go for sure, and try and find a 200W panel that is close on voltage to the current one and you will be good.
If you have the older AMT12-2 with the studs you could use that as a connection point if you had to by stacking rings. If the newer AMT with the spade fastons, I would not use that as you would not be able to get the cables you need into a single spade.
 
Forgot to mention that to wire in series, just plug one into the other.

To wire in parallel, you need two adapters, or you have to join wires in some sort of connector box. I'd use adapters.
 
wildebus said:
right,
So parallel is the way to go for sure, and try and find a 200W panel that is close on voltage to the current one and you will be good.
If you have the older AMT12-2 with the studs you could use that as a connection point if you had to by stacking rings. If the newer AMT with the spade fastons, I would not use that as you would not be able to get the cables you need into a single spade.
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As usual - all the answers I need. Thanks everyone and of course Wildebus. I haven't got the AMT12-2 yet so will make sure if poss I get the one with studs.
 
Owlhouse said:
As usual - all the answers I need. Thanks everyone and of course Wildebus. I haven't got the AMT12-2 yet so will make sure if poss I get the one with studs.
Click to expand...
Ah. All the current ones have Faston Tabs (Ablemail changed from Studs as it was overkill for the currents involved).

If you are connecting two panels in parallel, you would be best off doing that on the roof to save having to make another hole in the roof for the second pair of solar cables.
The significant majority of panels on sale use MC4 connectors. To parallel join a pair of panels with those connectors, use something like this
https://amzn.to/3URBRin - MC4 Splitter/Combiners. The one I linked to is just one of loads of ones listed.

If you don't have MC4 connectors (some panels such as Truma brand use another style), you could cut the cables and add MC4s and then use the combiners, or cut the ends off and use the following connectors ....
https://amzn.to/3IbVQ3D - Wago 221 Lever Connectors.
61ABTWjlnML._SL1500_.jpg

They will take upto 4mm2 cable, which will be enough for any solar panel and for the cable Burstner will have fitted.
You would have the +ve of one panel in one of the three, +ve of the second on the next of the three and then the cable into the roof into the third position.
You use one 3 way for +ve and one 3 way for -ve. Need to put these into a little box and make it waterproof.

The MC4 method is generally the easiest and what I would recommend if you have the option.
Bit of a write-up on the MC4s here if interested .... https://wildebus.com/posts/solar-panels-connections/
 
wildebus said:
Ah. All the current ones have Faston Tabs (Ablemail changed from Studs as it was overkill for the currents involved).

If you are connecting two panels in parallel, you would be best off doing that on the roof to save having to make another hole in the roof for the second pair of solar cables.
The significant majority of panels on sale use MC4 connectors. To parallel join a pair of panels with those connectors, use something like this
https://amzn.to/3URBRin - MC4 Splitter/Combiners. The one I linked to is just one of loads of ones listed.

If you don't have MC4 connectors (some panels such as Truma brand use another style), you could cut the cables and add MC4s and then use the combiners, or cut the ends off and use the following connectors ....
https://amzn.to/3IbVQ3D - Wago 221 Lever Connectors.
61ABTWjlnML._SL1500_.jpg

They will take upto 4mm2 cable, which will be enough for any solar panel and for the cable Burstner will have fitted.
You would have the +ve of one panel in one of the three, +ve of the second on the next of the three and then the cable into the roof into the third position.
You use one 3 way for +ve and one 3 way for -ve. Need to put these into a little box and make it waterproof.

The MC4 method is generally the easiest and what I would recommend if you have the option.
Bit of a write-up on the MC4s here if interested .... https://wildebus.com/posts/solar-panels-connections/
Click to expand...
Thanks again Wildebus - interesting article and lots of good info. 🤓
 
My panels have big black boxes under them, so it was easy to wire in parallel, then just one big cable through a boat deck gland down to the votronic duo control unit which is a 250, so if i want i can add a windsheild panel of 50w, i will be fitting a dedacated cig socket to the control unit.
ADvice is get a control unit a bit bigger than you require, handy if you want to add more later on.
 
Be very careful going down the, adding extra solar panel route.
It becomes addictive.
Demi’s first panel was a 100w. Now after several flat and tilting phases, she now has 500w tilting on the roof, and a further 200w folding set that can be deployed outside, and lives under the bed when travelling.
Doesn’t stop there. All that power, what can I do with it? Batteries 👍. The addiction moves on then too, electric kettles.
Before you know it, you’re mainlining, Toaster seems reasonable, doesn’t it? Only the start.
To quote the AA’s intro, “My name’s Trotter, I’m an electric addict.
The latest addition to my addiction is a microwave, air fryer and electric freezer.
 
No hope for you Del, you are definitely addicted lol
 
nabsim said:
No hope for you Del, you are definitely addicted lol
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Sad case, I'd admit. Although, as I'm spending more time in the van, (thank you for being so understanding Nic), I am becoming more aware that it takes no intelligence to be uncomfortable.
Would like an induction cooker! I have been told that I could use one, as long as I used utensils as least 60mm long, and didn't lean over to smell or check the food.
 
Trotter said:
Sad case, I'd admit. Although, as I'm spending more time in the van, (thank you for being so understanding Nic), I am becoming more aware that it takes no intelligence to be uncomfortable.
Would like an induction cooker! I have been told that I could use one, as long as I used utensils as least 60mm long, and didn't lean over to smell or check the food.
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I would think hard mate, I a, certain I am quite often closer than 60cm in the van. In a house maybe not so bad
 
I have been told that my cooking could kill me. I've always thought they meant too many unsaturated fats in the food. Not the cooking of it.

To explain the facts as I understand them.
Induction cookers work using magnetic fields, or some thing like that. Heart pacemakers don't react well to magnets. I'm trying to get by with a Infared cooktop. It's incredibly power hungry compared to the induction. Sometimes I'm reduced to using lpg 🤯 .

I'm not sure if it's a good thing, but Nic often remarks on a weight gain. Can't see it myself.
 
Trotter said:
I have been told that my cooking could kill me. I've always thought they meant too many unsaturated fats in the food. Not the cooking of it.

To explain the facts as I understand them.
Induction cookers work using magnetic fields, or some thing like that. Heart pacemakers don't react well to magnets. I'm trying to get by with a Infared cooktop. It's incredibly power hungry compared to the induction. Sometimes I'm reduced to using lpg 🤯 .

I'm not sure if it's a good thing, but Nic often remarks on a weight gain. Can't see it myself.
Click to expand...
Does that meen you dont fit the strong magnets to the electric meter at home. :unsure:
 
Trotter said:
I have been told that my cooking could kill me. I've always thought they meant too many unsaturated fats in the food. Not the cooking of it.

To explain the facts as I understand them.
Induction cookers work using magnetic fields, or some thing like that. Heart pacemakers don't react well to magnets. I'm trying to get by with a Infared cooktop. It's incredibly power hungry compared to the induction. Sometimes I'm reduced to using lpg 🤯 .

I'm not sure if it's a good thing, but Nic often remarks on a weight gain. Can't see it myself.
Click to expand...
Thought you had a halogen hob?
 
Trotter said:
No, Tis Infrared. Sez so on the box 😇 Anyone recommend the halogen,over the infrared?
Click to expand...
I thought they were the same. duckduck thinks the same :) .... "Halogen cooktops are also known as infrared hobs. It uses conduction and radiation to cook food. A ceramic glass surface takes a little longer to reach the desired temperature. Inferred instant light produces instant heat instead of a traditional metal coil."

Better than Solid plates or those curly rings for sure :)

I have a Halogen Oven. Never managed to cook anything in it successfully - it is far too aggressive :(
 
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