Solar Panel Question...

[ctva]

At present I have a 100w panel on one side of the boat where the spray dodgers usually are. This is fixed and gives between 5A and 1A in full sun depending on whether the sun is on that side or not. I am looking to add a second panel on the opposite side so one will always be in the shade (no other mounting options) but one will always be in the sun. At present I have a 10A PWM controller.

Panel -
Peak power: 100W
Maximum power voltage: 19.3V
Maximum power current: 5.18A
Open circuit voltage: 22.9V

Controller - 10A Solar Controller (Photonic Universe)

With the configuration, will I need to up to a 20A controller (current 10A says does up to 160W) but with the panels being back to back will the current 10A one do?

Secondly from what I have read, it would be better in parallel due to the shading but where I'm confused is the benefits (if any) of getting a MPPT over the cheaper PWM controller for this set up?

Any thoughts would be appreciated.

 

[mattnj]

10a one is fine, just wire in both panels to that.

 

[Jamie Dundee]

If you’re planning on wiring the two panels into one controller, bearing in mind one panel will always be producing more than the other, you need to put a blocking diode on each panel. 12V solar panels charging kits for caravans, motorhomes, boats, yachts, marine

 

[RupertW]

If you’re planning on wiring the two panels into one controller, bearing in mind one panel will always be producing more than the other, you need to put a blocking diode on each panel. 12V solar panels charging kits for caravans, motorhomes, boats, yachts, marine

Only if the panels are in series - if in parallel then you just need to check the panels have similar voltage characteristics.

 

[Jamie Dundee]

Only if the panels are in series - if in parallel then you just need to check the panels have similar voltage characteristics.

Not according to the spec. This MC4-compatible adaptor with a 10A blocking diode allows you to connect several solar panels in parallel (to common positive and common negative terminals) and run them through a single solar charge controller. It eliminates the risk of back flow of power through solar panels, particula

 

[RupertW]

Not according to the spec. This MC4-compatible adaptor with a 10A blocking diode allows you to connect several solar panels in parallel (to common positive and common negative terminals) and run them through a single solar charge controller. It eliminates the risk of back flow of power through solar panels, particula

Woops - of course are right - my panels have those internally fitted. I was thinking of bypass diodes.

 

[thinwater]

I'd move the panel on top of the dodger; the ouput will be enough more you may not need the second panel. Put the other one in front of it (don't know the space). But the idea of intentionally installing the panels in such a way that one is always 100% shaded is very strange. You should be able to get a fairly consistent 4-6 amps from a single 100W panel in a better location. I probably get more consistent amps from a single 50W panel mounted in front of the companionway (my F-24, not the boat in the avitar).

Tip: sometimes it helps to swing the boom out to one side anchor to eliminate shadows.

 

[PaulRainbow]

If you fit the panels to the top of the guard wires so they swing up and down you can have one down and one up (say the Sun is on the port side, have the port side one down and the Stb one up.

Deliberately fitting them so only one works is (as Thinwater says) a very odd choice.

A 10a controller is not good enough for 200W of solar., you need a 15A controller, or fit a 10A to each panel. The Maximum power current: 5.18A is at the Maximum power voltage: 19.3V If the controller is "converting" the 19.3V to 13V-14V the current could be 14 or so amps.

 

[cherod]

" wind hippie " the intrepid solo female youtuber has an interesting vid this week on her installation . KIS

 

[ctva]

Not according to the spec. This MC4-compatible adaptor with a 10A blocking diode allows you to connect several solar panels in parallel (to common positive and common negative terminals) and run them through a single solar charge controller. It eliminates the risk of back flow of power through solar panels, particula

I've not seen any reference to this in any of the reading I've done so far. Can you elaborate or provide a link, thanks?

If you fit the panels to the top of the guard wires so they swing up and down you can have one down and one up (say the Sun is on the port side, have the port side one down and the Stb one up.

Yes, that is what I can do at the moment when at anchor but not very convenient.

The current panel is fitted on the starboard side as that is the aspect for keeping the batteries charged in the berth, however given the usual SW/W winds then at anchor, the port side is to the sun, hence the requirement. As I said in the OP, space and options dictate that these are the only two places available to use. I will get the 20A controller but with a small set up like this in parallel to take account of the shading, is it worth the MPPT over the PWM?

 

[PaulRainbow]

With the proposed setup any potential gains from fitting MTTP are likely to be small.

 

[Jamie Dundee]

I've not seen any reference to this in any of the reading I've done so far. Can you elaborate or provide a link, thanks?

Link in post #4.

 

[William_H]

As always with solar panels it is the difficulty of mounting that determines arrangement. I would respect the OP choice of location of the panels. Though many do it differently. Yes wire in parallel. re need for isolation diodes I am doubtful so suggest just try it without. ol'will

 

[ctva]

OK so taking on board all the above info, this appears to be the setup I need.

 

[LadyInBed]

I can understand that having the panels vertical when the boat isn't being used or when in a marina, but when at anchor, you need the panels to hinge on the top rail to have them at any angle, even over horizontal for maximum benefit.

 

[ctva]

I can understand that having the panels vertical when the boat isn't being used or when in a marina, but when at anchor, you need the panels to hinge on the top rail to have them at any angle, even over horizontal for maximum benefit.

The one currently one does but as I indicated in the OP, it's the wiring requirements and MPPT v PWM that I need info on.

 

[noelex]

The cheapest option would be to stay with your existing single PWM 10A regulator with the solar panels in parallel. This will work, nothing will be damaged, and the output will be reasonable. Blocking diodes are likely to lose more than they gain, although this does depend on the panel. Ideally connect a covered panel to a battery and measure the discharge current for your particular panels. It will be very small In most cases. This is the worst case, in most situations the voltage difference and hence the current will be lower again.

A better option is to switch to MPPT controllers. In your case the solar panels will often experience different conditions with corresponding disparate maximum power points. Unfortunately, a single MPPT controller can only accept one input voltage at a time. The results will still be better than a single PWM regulator, but only slightly.

The best solution is two MPPT controllers so the input voltage of each panel is tracked separately. If you do decide this is worthwhile, stick to the better quality controllers such as the Victron range. The cheap MPPT controllers are generally poor. Whether the considerable extra cost of this solution is worthwhile is something that will depend on your power requirements and budget.

 

[PaulRainbow]

The cheapest option would be to stay with your existing single PWM 10A regulator with the solar panels in parallel. This will work, nothing will be damaged, and the output will be reasonable.

A 10A controller is not suitable for 200W of solar panels, the suppliers correctly state it is for use with a maximum 160W. 200W of solar is easily capable of providing close to 15A

 

[noelex]

A 10A controller is not suitable for 200W of solar panels, the suppliers correctly state it is for use with a maximum 160W. 200W of solar is easily capable of providing close to 15A

The two solar panels cannot produce close to 15A with a PWM controller. This is only possible with the voltage conversion incorporated into a MPPT controller.

The maximum current with a PWM controller with both panels in ideal conditions will only be slightly above the Imp which is 2x5.18= 10.36A. The absolute limit will the short circuit current, which is not listed, but will be about 2x5.6 = 11.2A for his panels. So close to 15A is not remotly possible with a PWM controller.

While this is slightly above the maximum 10A current specification of the existing controller, the controller will self limit the current to protect itself should this theoretical limitation ever be reached. (Note this protection does not apply to voltage, if you exceed the maximum voltage most controllers will be instantly damaged). Given the set up that Chris is describing, exceeding 10A with a PWM controller is very unlikely even briefly. The two solar panels will not be producing their maximum output simultaneously.

So the existing controller is a practical and safe solution, although given the constant need for more electrical power on a yacht, personally I would pay the additional price to update to two MPPT controllers. This will produce the highest output.

 

[Bobc]

The two solar panels cannot produce close to 15A with a PWM controller. This is only possible with the voltage conversion incorporated into a MPPT controller.

The maximum current with a PWM controller with both panels in ideal conditions will only be slightly above the Imp which is 2x5.18= 10.36A. The absolute limit will the short circuit current, which is not listed, but will be about 2x5.6 = 11.2A for his panels. So close to 15A is not remotly possible with a PWM controller.

While this is slightly above the maximum 10A current specification of the existing controller, the controller will self limit the current to protect itself should this theoretical limitation ever be reached. (Note this protection does not apply to voltage, if you exceed the maximum voltage most controllers will be instantly damaged). Given the set up that Chris is describing, exceeding 10A with a PWM controller is very unlikely even briefly. The two solar panels will not be producing their maximum output simultaneously.

So the existing controller is a practical and safe solution, although given the constant need for more electrical power on a yacht, personally I would pay the additional price to update to two MPPT controllers. This will produce the highest output.

You'll also get some losses through the cables, so I too reckon you'll be fine with 2 panels in parallel to your existing 10w PWM controller.