MPPT Solar Controller Rating

[Ammonite]

I'm in the process of installing 1 x Eco-worthy 100W rigid and 2 x Renogy 100W rigid solar panels. These will be installed in parallel due to potential shading issues. The Eco-worthy is about 20% smaller than Renogy and the various reviews I've read suggest 100W is optimistic although it's the ideal physical size, so I've probably got a max of 280/290W in perfect conditions which I suspect is unlikely given I'm based on the South Coast. My existing Victron Smartsolar 100/20 12v is rated to 290W. Is this OK? I'm hoping that in the unlikely event the panels were to deliver 300W the Victron would clip the input given the in-built protections?

 

[Bobc]

It'll be fine

 

[Sea Change]

Yes you'll be fine, you can oversize the MPPT to a certain degree (it's in the region of 50% but don't rely on my memory for that).
And in practice as you say you'll never actually achieve 300w from those panels.

 

[Baggywrinkle]

How to wire mismatched panels and the effect on output.

 

[PaulRainbow]

It will be fine. In the unlikely event that the 290w is exceeded the controller will only process 290w.

It's worth noting (although it doesn't apply in this case) that if you exceed the rated voltage the controller will shut down.

 

[Ammonite]

How to wire mismatched panels and the effect on output.

Thanks for sharing this, although in this instance the voltages of the panels are within 0.2v of each other so the mismatch will be negligible.

For the other posters. Thanks for the reassurance. I thought this would be the case but didn't want to risk cooking the controller.

One more question. Two of the panels are going to be rail mounted but the rail is going to be mid way between the middle and top guard wire. I'm going with NOA adjustable mounts which will allow me to extend the panel beyond the top wire, and I'm also fitting a pelican hook to the top wire so this can be removed in port if needed, but what would be the likely impact of having a 4mm guard wire running the length of the panel approximately 150mm above the face? Fitting the rail to the top wire isn't a practical option in this case as it would mean replacing the gates on each side.

 

[TSB240]

Thanks for sharing this, although in this instance the voltages of the panels are within 0.2v of each other so the mismatch with be negligible.

For the other posters. Thanks for the reassurance. I thought this would be the case but didn't want to risk cooking the controller.

One more question. Two of the panels are going to be rail mounted but the rail is going to be mid way between the middle and top guard wire. I'm going with NOA adjustable mounts which will allow me to extend the panel beyond the top wire, and I'm also fitting a pelican hook to the top wire so this can be removed in port if needed, but what would be the likely impact of having a 4mm guard wire running the length of the panel approximately 150mm above the face? Fitting the rail to the top wire isn't a practical option in this case as it would mean replacing the gates on each side.

We have ours mid mounted. I tested the shading effect of the top guard wire with a mid day sun. It was less than 2 percent loss of output. Being mid mounted you can also angle them inboard or outboard without need for extending stays just using a saddle clamp onto the mid mounting tube.

 

[noelex]

Thanks for sharing this, although in this instance the voltages of the panels are within 0.2v of each other so the mismatch with be negligible.

As others have said, you should be fine with the 100/20. Make sure you provide plenty of ventilation, as this controller runs relatively hot and it will be working close to its limit in your installation.

The only online specifications I can find suggest that the Eco-Worthy is a relatively low voltage panel with a Vmp of 18 V and a Voc of 21.6 V. The Renogy is more typical of a "12v" panel with a Vmp of 20.4 V and a Voc of 24.3 V. The companies may have changed their design/specifications recently, but it is worth checking the voltages again to check the compatibility, as it is easy confuse Vmp and Voc. You need to compare like with like (preferably temperature adjusted Vmp).

 

[Ammonite]

Thanks. The Vmp and Voc for the panels I've purchased are 20.4v, 24.3v (Renogy) and 20.2v, 24.5v (Eco-worthy)

 

[noelex]

Thanks. The Vmp and Voc for the panels I've purchased are 20.4v, 24.3v (Renogy) and 20.2v, 24.5v (Eco-worthy)

That will work fine .