15a v 30a Victron SCC?

[Mike & Rebecca]

This question is specific to the SCC, unless I've left something really obvious out of the question. You've all been great to provide additional comments to my questions and I hate to see you repeat those. I've been keeping notes!

I just want confirmation of the recommendation from Connected Current that I purchase the 75/15 SmartSolar MPPT instead of the 100/30 model. I like the 75/15 as it's about 1/2 the cost. But I'm ok with spending the extra if there's a significant benefit.

We have 1 x 165W Furrion panel and unlikely to add more panels anytime soon. We rarely dry camp, are under shade in most locations where we would, and have a Honda 2200i as back up. No, I don't need to run the AC with the Honda. According to the Furrion manual Howard provided in the reference library, the max open circuit volt of this one panel is 23.12V - so theoretically the 75/15 would handle up to 3 x 165W panels by my math.

According to the AmSolar video on selecting the right SCC (from the Reference Library) the 1 x 165W panel does almost fully utilize the SCC's max wattage output, but the video also said that if the solar array exceeds that nothing will be damaged. Just not as efficient.

Early in my posting about our new trailer someone mentioned not overspending and over building until you've used the trailer enough to really understand the needs. Given the fact we're unlikely to expand on the solar array anytime in the next 1-2 years, and may never, is it worth moving to the 100/30 model, or just stick with the 75/15? I'm just looking for any really obvious (but not to me) objections with going with the smaller SCC.

Thanks!

[acoleman43]

I think you should be OK with the 75/15 with just the single 165W panel. The 75/15 solar array capacity is rated at a max 220W at 12V so you really can't add another panel with this solar charge controller. The voltage and amperage look fine.

Solar Charge Controller






165W Panel:





Keep in mind, the colder it is, the more energy the panel produces. the voltage/current shown in panel specs could increase a few percentages if temp is freezing or less.

[Mike & Rebecca]

I think you should be OK with the 75/15 with just the single 165W panel. The 75/15 solar array capacity is rated at a max 220W at 12V so you really can't add another panel with this solar charge controller. The voltage and amperage look fine.

Solar Charge Controller






165W Panel:





Keep in mind, the colder it is, the more energy the panel produces. the voltage/current shown in panel specs could increase a few percentages if temp is freezing or less.

I must have missed something in the AmSolar video, or just misunderstood. You're thinking an additional 1 panel would cause harm? Or the 75/15 SCC just wouldn't be optimal?

What's the limiting factor? I appreciate the specs you circled.

[howson]

In the Array Wattage Calculation portion of Garret's video he uses (W x .9) / Battery Voltage = Amperage In your case (165W * .9)/12 = 12.375A If you double the wattage of the panels (two 165W panels) that's (330 * .9) / 12 = 24.75A Obviously that exceeds the spec'd capability of the controller.

However.

In the next segment (Too Much Solar) Garret explains that what that means is you'll lose some of the peak sun hours (controller won't be able to output all the power available). This starts at about 4:14 of the video. You referenced this section in your first post.

If you did get two 165W panels and wired them in series, the maximum short circuit current is still 9.49A but now the maximum open voltage is 46.24V. Both are within specs of the 75-15 controller. Where you would get into trouble is wiring the two 165W panels in parallel. Short circuit current in this case is just under 19A (see the "Current Considerations" portion of the video around the 3:00 minute mark).

Also note that Garret says in the video that a 30A controller is their nominal recommendation for a 450W system. That's a long way to say I agree with Allen--if you get the 15 controller stick with one panel.

You know by now I'm an unabashed Victron fan--their stuff is just way too interesting for this self-identified geek. But I must admit to thinking that spending the $$ for a Victron for a single 165W panel is already overkill...so my .02 is to get the larger controller so you're ready to upgrade.

An option that's less expensive (and stuff you should have anyway): wire in a disconnect between the panels and the Furrion, and wire in a disconnect between the battery bank and the Furrion. Only turn on the controller when you know you want it to charge the battery. (This will eliminate any concern over the component--if it's off it can't hurt anything.) It will also give you an idea of how often you turn on the controller--if it's frequent maybe you do want to go big. If you never turn on the controller...why mess with solar at all?

[Mike & Rebecca]

In the Array Wattage Calculation portion of Garret's video he uses (W x .9) / Battery Voltage = Amperage In your case (165W * .9)/12 = 12.375A If you double the wattage of the panels (two 165W panels) that's (330 * .9) / 12 = 24.75A Obviously that exceeds the spec'd capability of the controller.

However.

In the next segment (Too Much Solar) Garret explains that what that means is you'll lose some of the peak sun hours (controller won't be able to output all the power available). This starts at about 4:14 of the video. You referenced this section in your first post.

If you did get two 165W panels and wired them in series, the maximum short circuit current is still 9.49A but now the maximum open voltage is 46.24V. Both are within specs of the 75-15 controller. Where you would get into trouble is wiring the two 165W panels in parallel. Short circuit current in this case is just under 19A (see the "Current Considerations" portion of the video around the 3:00 minute mark).

Also note that Garret says in the video that a 30A controller is their nominal recommendation for a 450W system. That's a long way to say I agree with Allen--if you get the 15 controller stick with one panel.

You know by now I'm an unabashed Victron fan--their stuff is just way too interesting for this self-identified geek. But I must admit to thinking that spending the $$ for a Victron for a single 165W panel is already overkill...so my .02 is to get the larger controller so you're ready to upgrade.

An option that's less expensive (and stuff you should have anyway): wire in a disconnect between the panels and the Furrion, and wire in a disconnect between the battery bank and the Furrion. Only turn on the controller when you know you want it to charge the battery. (This will eliminate any concern over the component--if it's off it can't hurt anything.) It will also give you an idea of how often you turn on the controller--if it's frequent maybe you do want to go big. If you never turn on the controller...why mess with solar at all?

Ditch the solar all together (install disconnect for the solar array and just leave it off?) I love that Howard! Given the other parameters of my typical uses that would actually work.

The worst that happens is I decide to add in the Victron SCC later. In the meantime I have effectively cut the Furrion SCC (and my concerns) out of the system. And I'm not really using the solar anyway.

Genius!