Solar panels

[newcampers]

Hi.

Looking for some help please.
I've got this panel available to me.
Would it be suitable for caravan. It'd only really be for keeping the battery charged not Looking to go off grid

 

[Mr Plodd]

Looks like it's 135w, so more than enough to keep a battery well topped up. You just need to think about
A) Some form of controller so you dont "cook" the battery on a sunny day
B) Where are you going to put it? If permanently on the roof you will need some suitable brackets/mounts. Also don't forget the weight, thats 12.5 kg off your payload , which on many caravans is 7.5-10% of the total!

 

[newcampers]

Thanks.
I'm not sure on the controller.
Amazon have some for 20 odd £.
Not sure if they would be any good. Not wanting to cook the battery or worse burn the van down.

I was thinking of having it fixed to the roof for convenience but didnt think about the weight.

First time I've looked at having a van so all new to me.

 

[newcampers]

They have some on ebay for £20
Specs below
Just needed to keep a battery charging


Output current 1600 (mA)
Battery capacity 1600 (mAH)
Load voltage: 12V
Output voltage 5V 18V (V)
Solar panel power: 200W
Operating voltage of the solar panel: 18V
Open circuit voltage of the solar panel: 21.6V
Short circuit current solar panel: 3A (maximum)
Output port: Dual USB, 5V / 2.5A
Battery panel specification: high-efficiency monocrystalline board
Size: About 11.3 x 11.3 inches
Working temperature: -35℃+60℃
Type: With 50A controller

 

[Mr Plodd]

Can't see a 200w solar panel measuring under 12" square ! 20w maybe.

 

[newcampers]

I'm hesitant to believe it's 200w either probably a typo

 

[trevormonty]

These PWM work fine and are everywhere on web, should be able to pick them up for <£10.
Buy 30A version. Not as efficient as MPPT but for your uses doesn't matter. Can always upgrade to MPPT later.

Solar Controller 20A | The Warehouse

Buy Solar Controller 20A at The Warehouse

www.thewarehouse.co.nz

 

[Guzzilazz]

MPPT is a waste of time for a single panel, the benefits are really made on multiple panels, as you connect the panels in series, so raising the voltage into the control to typically 40V , and even over 20 V on lower light conditions, meaning that the output voltage to the battery is within the charging parameters

Whichever controller you choose, make sure you set the correct battery type, as incorrect type can damage the battery.

 

[Buckman]

MPPT is a waste of time for a single panel, the benefits are really made on multiple panels, as you connect the panels in series, so raising the voltage into the control to typically 40V , and even over 20 V on lower light conditions, meaning that the output voltage to the battery is within the charging parameters

Whichever controller you choose, make sure you set the correct battery type, as incorrect type can damage the battery.

Fitting a MPPT controller to our caravan has made a big difference during the winter months and the sun is low in the sky.

 

[Anseo]

MPPT is a waste of time for a single panel, the benefits are really made on multiple panels, as you connect the panels in series, so raising the voltage into the control to typically 40V , and even over 20 V on lower light conditions, meaning that the output voltage to the battery is within the charging parameters

Whichever controller you choose, make sure you set the correct battery type, as incorrect type can damage the battery.

Hi Guzzilaz, I was thinking about this yesterday evening and it didn't quite fit with my recollection of the differences between MPPT and PWM controllers.

I thought I would check with AI, below is the response, happy to hear if you concur or otherwise.


Q: Is there any point in having an mppt solar charge controller as opposed to a pwm controller if only one solar panel is used.

ChatGPT said:​

Yes, there can still be a significant advantage to using an MPPT (Maximum Power Point Tracking) solar charge controller over a PWM (Pulse Width Modulation) controller, even if you are only using one solar panel. The key difference lies in how each controller manages the power from the solar panel, which affects overall efficiency.
Here are some reasons why an MPPT controller may still be beneficial with a single panel:

1. Higher Efficiency in Energy Harvesting​

• MPPT controllers maximize the power output by adjusting the input voltage and current to find the optimal "Maximum Power Point" of the solar panel. This can result in a 10-30% increase in energy harvesting compared to a PWM controller, especially in less-than-ideal conditions (like overcast skies or partial shading).
• PWM controllers simply match the voltage of the panel to the battery, which often results in energy loss if the panel voltage is higher than the battery voltage.

2. Handling Higher Voltage Panels​

• With an MPPT controller, you can use a panel with a higher voltage than the battery (e.g., a 24V panel with a 12V battery) because the controller will step the voltage down and convert excess voltage into additional current. This isn't possible with a PWM controller, which essentially wastes the excess voltage.

3. Better Performance in Varying Weather​

• MPPT controllers adapt better to changes in sunlight, temperature, and other environmental factors. This leads to more consistent performance, especially during the early morning, late afternoon, or on cloudy days.

4. Suitability for Future Expansion​

• Even if you only have one panel now, an MPPT controller may offer more flexibility for future system expansion, allowing you to add more panels without needing to upgrade the controller.

When a PWM Controller May Suffice:​

• If the panel's voltage is already well-matched to the battery (e.g., a 12V panel with a 12V battery).
• If the cost difference between PWM and MPPT is significant and you're operating in a sunny, consistent environment where the extra efficiency might not justify the price difference.

In conclusion, while a PWM controller may be more cost-effective for smaller setups, an MPPT controller provides better efficiency, adaptability, and potential for expansion, even with a single panel.

 

[newcampers]

MPPT is a waste of time for a single panel, the benefits are really made on multiple panels, as you connect the panels in series, so raising the voltage into the control to typically 40V , and even over 20 V on lower light conditions, meaning that the output voltage to the battery is within the charging parameters

Whichever controller you choose, make sure you set the correct battery type, as incorrect type can damage the battery.

I got a cheap controller from amazon.
The battery type just shows B1 B2 3
How do I know what's what the instructions are pretty useless in detail

 

[trevormonty]

I got a cheap controller from amazon.
The battery type just shows B1 B2 3
How do I know what's what the instructions are pretty useless in detail

Without product details can't help.

 

[newcampers]

Without product details can't help.

Am I ok to post links the them

 

[otherclive]

Yes

 

[newcampers]

Sorted it now thanks, YouTube helped

 

[Hutch]

I be.ieve the new "Stick on type panels. Are lighter, any one know ?

 

[Guzzilazz]

So, the types of panel are rigid, semi-flexible and flexible. The latter are poor, the "sticky panels" are semi-flexible and yes they are usually stuck with sealant - BUT not with a bead all the way around which is the obvious way. The heat generated under the panel isn't insignificant (my boat had two150 W panels secured to 1.5" marine ply, and on a good day the inside of that ply was warm to the touch.

The semi flex are much lighter but can only accept a limited bend, in some respects the rigid on a frame with a gap underneath is a pretty good solution. The rigid panels are more efficient than Semis which are more efficient than flexible

 

[Guzzilazz]

Hi Guzzilaz, I was thinking about this yesterday evening and it didn't quite fit with my recollection of the differences between MPPT and PWM controllers.

I thought I would check with AI, below is the response, happy to hear if you concur or otherwise.


Q: Is there any point in having an mppt solar charge controller as opposed to a pwm controller if only one solar panel is used.

ChatGPT said:​

Yes, there can still be a significant advantage to using an MPPT (Maximum Power Point Tracking) solar charge controller over a PWM (Pulse Width Modulation) controller, even if you are only using one solar panel. The key difference lies in how each controller manages the power from the solar panel, which affects overall efficiency.
Here are some reasons why an MPPT controller may still be beneficial with a single panel:

1. Higher Efficiency in Energy Harvesting​

• MPPT controllers maximize the power output by adjusting the input voltage and current to find the optimal "Maximum Power Point" of the solar panel. This can result in a 10-30% increase in energy harvesting compared to a PWM controller, especially in less-than-ideal conditions (like overcast skies or partial shading).
• PWM controllers simply match the voltage of the panel to the battery, which often results in energy loss if the panel voltage is higher than the battery voltage.

2. Handling Higher Voltage Panels​

• With an MPPT controller, you can use a panel with a higher voltage than the battery (e.g., a 24V panel with a 12V battery) because the controller will step the voltage down and convert excess voltage into additional current. This isn't possible with a PWM controller, which essentially wastes the excess voltage.

3. Better Performance in Varying Weather​

• MPPT controllers adapt better to changes in sunlight, temperature, and other environmental factors. This leads to more consistent performance, especially during the early morning, late afternoon, or on cloudy days.

4. Suitability for Future Expansion​

• Even if you only have one panel now, an MPPT controller may offer more flexibility for future system expansion, allowing you to add more panels without needing to upgrade the controller.

When a PWM Controller May Suffice:​

• If the panel's voltage is already well-matched to the battery (e.g., a 12V panel with a 12V battery).
• If the cost difference between PWM and MPPT is significant and you're operating in a sunny, consistent environment where the extra efficiency might not justify the price difference.

In conclusion, while a PWM controller may be more cost-effective for smaller setups, an MPPT controller provides better efficiency, adaptability, and potential for expansion, even with a single panel.

A single panel produces on open circuit about 22V max. This reduces quite quickly on current draw (charging) to about 19V. Charging voltages for batteries are in the 14.4-15 ish range depending on battery type. Two panels in series raise the input voltage to the controller from 19V to 38V, and that results in a huge gain from MPPT, the advantage over a PWM on a single panel is much less.

 

[Buckman]

So, the types of panel are rigid, semi-flexible and flexible. The latter are poor, the "sticky panels" are semi-flexible and yes they are usually stuck with sealant - BUT not with a bead all the way around which is the obvious way. The heat generated under the panel isn't insignificant (my boat had two150 W panels secured to 1.5" marine ply, and on a good day the inside of that ply was warm to the touch.

The semi flex are much lighter but can only accept a limited bend, in some respects the rigid on a frame with a gap underneath is a pretty good solution. The rigid panels are more efficient than Semis which are more efficient than flexible

I think one of the big issues was that if the flexible one went faulty, it was impossible to remove due to the type of glue used. Also you could not put the replacement panel on top of the old one. However this was a few years go when we had a rigid one fitted as also looked at the flexible ones.

 

[trevormonty]

Installer I talked stopped doing flexible ones as they failed after couple years. Only does heavier rigid ones now.

 

[Guzzilazz]

I think one of the big issues was that if the flexible one went faulty, it was impossible to remove due to the type of glue used. Also you could not put the replacement panel on top of the old one. However this was a few years go when we had a rigid one fitted as also looked at the flexible ones.

The stuff used in the marine environment is Sikaflex 291. When you use that, the secret is to put thickish washers under the corners; stripe the glue across the panel and not around the outside. To remove, cheese wire under the panel in the spaces mentioned...

I changed 2x 45 W semi flexible panels (originally installed 2008) for 2x150W panels in 2016. The original 2 panels were sold on to friends and are still ably charging batteries. Don't know about the 150's because the boat was sold in 2021, but at that point they were shoving out power hand over fist. Semi Flex are extensively used on sailing boats because of the rope tangling factor.