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jfrohoff asked

Is it OK to put more thann 30 amps into SmartSolar 100/30 from panels?

Hello all, I have 4 100 watt Renogy 12v panels setup as 2S, 2P into a 100A Lithium (will upsize to two later this year). I want to purchase a 100/30 Smart Solar MPPT. due to very low radiance during winters up here in Seattle I will only harvest .5 KWh/day based on the Victron Calculator, but three times that, or more during summer (about 28A if full power, which will likely never happen). Can I add another 200 watts (2S) to boost winter output even even if full power into the controller exceeds the 30 amp max output current during summer? or do I need to buy another MPPT? With two MPPT I could exceed max 30A recharge C rate, so not preferable. Thx.

@jfrohoff

MPPT Controllers
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seb71 answered ·

What's the Isc for those 100W panels?

Can't be very high, so 3 strings (of two panels each) in parallel should be OK.


Also what's the Voc? If you get 6 of those panels, you might be able to put 3 in series, so only 2 strings in parallel.


In both cases make sure that the new panels are identical with the old panels.


Also take a look at your price difference between SmartSolar 100/30 and a SmartSolar 150/35. The 150V limit of the second one allows more flexibility if you want to upgrade to bigger panels.


Note:

You can limit the charging current from the MPPT settings.

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jfrohoff avatar image jfrohoff commented ·

Whoops! First time on forum and I accidentally posted my reply as another answer - didn’t initially notice the comment icon.


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jfrohoff answered ·

Thanks. Isc is 6.1A. Voc is 21.7v.

I wanted to add more panels due to minimal winter radiance, yet don’t want to overpoer the controller during summer. I’ll be ok with the voc since I need to go with 2S strings based on the panels I have so as to not mis-match. But if I exceed 15 amps input on the 75/15 on a very sunny day will it safely handle it? From what I read in the manual the “15” in 75/15 means the max battery charge output current, but does that also apply as a never-to-exceed value in the panels input to the controller? thx

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seb71 avatar image seb71 commented ·

In your first post you said you want to get a SmartSolar100/30.

Now it's a 75/15?


Maximum input current (max Isc of the PV array) is listed in the MPPT datasheet.


Do not put different PV panels on the same MPPT charger.


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jfrohoff avatar image jfrohoff seb71 commented ·

Thx @Seb71. Sorry for being confusing. I already own a 75/15. After more research I thought I will need to switch to a 100/30 for a larger array. I think you answered my question and it tells me the solution … “ Do not put different PV panels on the same MPPT charger.”. I’ll go ahead and purchase a 100/30 or 150/35 for my second string (2 x 100 watt glass Renogy panels) leaving room for some expansion and keep the first 200 watt 2S string (2 x Renogy flexible 100 watt) on the 75/15. Though I will still need to limit max charger output amps if using both strings until I can buy a second battery. I know the flexible panels will have a short lifespan. Portability is critical for at least one string due to the application. I’ll read the data sheet again for max MPPT input current limits; missed it on first read. Thx.

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jfrohoff avatar image jfrohoff seb71 commented ·

The isc and voc I gave you are for the 100 watt flexible panels.

I read the controller spec sheet again as recommended. The footnotes contain the info I was asking about.

“1a) If more PV power is connected, the controller will limit input power.” (Obviously wasting power, not good)

“2) A PV array with a higher short circuit current may damage the controller.”

@Seb71 Your answer of putting different panel model strings on different controllers appears to be the best solution.

i obviously need to do more research on handling strings of panels with different specs.

Thx.

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