How to add another solar panel? (1 Viewer)

[TheMachMan]

Have a 115W on the roof connected to Victron MPPT 75/10 but want to add another 100W on the roof, and also use a portable panel. Any tips?
If possible could I wire the extra panel in parallel on the roof as it’s not easy to run a separate cable into the van.

 

[jollyrodger]

Usually as you suggested wire in Parallel.
Don't forget to disconnect panel(s) from regulator.
Then
When restarting system batteries connected first before bringing panels online.

Is how I was taught.

 

[Guigsy]

If you run panels in parallel, the panel that's giving the lowest voltage will drag down the other panels to the same level. So you should try to get panels with similar voltage profiles.

With a 75/15, you're limited to a maximum of 15 amps to the battery, which will be roughly 200 watts. So you'll collect all the rays early on in the day, but when the sun gets higher, the controller will hit it's limit. This isn't an issue, other than you'll hit maximum supply pretty quickly during the summer.

 

[Carpmart]

If you run panels in parallel, the panel that's giving the lowest voltage will drag down the other panels to the same level. So you should try to get panels with similar voltage profiles.

With a 75/15, you're limited to a maximum of 15 amps to the battery, which will be roughly 200 watts. So you'll collect all the rays early on in the day, but when the sun gets higher, the controller will hit it's limit. This isn't an issue, other than you'll hit maximum supply pretty quickly during the summer.

You saved me replying except to say the OP has a 75/10 controller, so will likely be over panelled!

 

[Guigsy]

You saved me replying except to say the OP has a 75/10 controller, so will likely be over panelled!

Yep, misread.

So peak power won't actually be much more than they're getting now. On sunny summer days, total yield probably won't be much better than they're already getting. But in autumn and spring, when most of the day is below peak, it'll be a bit more useful.

Personally I don't think it's worth the effort without upgrading the controller.

Edit: if you upgrade the controller, make sure the wiring will take it!

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[TheMachMan]

Not sure how I’d know if the cable was correctly sized. I’d be using the existing one.
Would a separate foldable panel be easier? Though not sure how it would be integrated into the system?

 

[headlight]

Not sure how I’d know if the cable was correctly sized. I’d be using the existing one.
Would a separate foldable panel be easier? Though not sure how it would be integrated into the system?

Why not fit another 115 watt in parallel and change the controller to a 75/15.
The 75/15 is rated at 220 watts so you would be 10 watts over but in reality you are unlikely to max the panels out and even if you do the Victron MPPT will be fine.
BTW 2 x 115 watt panels in parallel to a Victron 75/15 MPPT is exactly what I have after I added a second 115 watt panel.

 

[Jimbohorlicks]

I doubt you would ever reach 10amps with 2 x115watt panels . Certainly not in the UK.
Personally I would add another similar panel and just try it. Are you able to measure the amps from your existing panel ?does your controller give you a reading?

 

[Jabstatt]

Put a similar panel in series.
Wiring is then ok!

Tony

 

[TheMachMan]

Thanks, unfortunately I don’t have enough space for another panel of the same output. I guess I could swap it for a 200W panel, and update the Victron MTTP. I would then have about 1.6m x .65m on the flat roof ridges, there’s a bit more around them.

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[TheMachMan]

Been up on the roof for another look. The existing panel is by Victron and has MC4 connections. So I guess the simplest way forward would be a similarly connected larger one that was as near to max output of 10A so I can keep the MPPT 10? Are there any recommendations on suitable panel manufacturers and types, I’ve seen Poly & Mono crystalline mentioned.

 

[Guigsy]

Been up on the roof for another look. The existing panel is by Victron and has MC4 connections. So I guess the simplest way forward would be a similarly connected larger one that was as near to max output of 10A so I can keep the MPPT 10? Are there any recommendations on suitable panel manufacturers and types, I’ve seen Poly & Mono crystalline mentioned.

If you go to the Victron site, you can see the specs of the panel. I've got a Victron mono and it seems to match the Renogy panels fairly well... which I got cheap.