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mvader (Victron Energy) avatar image
mvader (Victron Energy) asked

New: Matching PV Array to Solar charger calculator on our website

Hello all!

After asking for your input in our new Wiring Unlimited book, today I have something else: an online calculator for PV Panels & MPPTs.

Since a long time we have the excellent excel sheet as made by Bob Hopman, one of our German sales managers, and his accompanying blog post that explains all the details.

Now the we have the same feature on our website. On top of what the excel sheet already did; this page also suggests the matching MPPT Solar Chargers and it has a graph of expected energy yield.

To try it out, go to our Solar Charger MPPT Charge Controller overview page, and click this link:


Here is a preview of the page:

MPPT Controllers
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Jay Kote avatar image
Jay Kote answered ·

I like web version. I could not get excel to accept anything other than 12v. I think it must have something to do with my older version of Excel, as Im sure others would have raised this point.


  1. One down side of spread sheet is it has predefined 12, 24, 36, 48v setting. It would be nice to be able to input non-standard voltage levels for none standard battery voltages.
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mvader (Victron Energy) avatar image mvader (Victron Energy) ♦♦ commented ·

Hi, you mean 36V ?


36 V is already a bit of an edge case (quite uncommon); and for anything else its really so uncommon that I don’t see the benefit of further adding features for that to the calculator.

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Jay Kote avatar image Jay Kote mvader (Victron Energy) ♦♦ commented ·

Actually, I saw another post saying they are using 22v Tesla battery and more and more people are doing it. My customer is using a custom battery that is rated for 18v - 22v as well. I could use it for that. And you never know what other size batteries people will use -- not because of nominal, but what low voltage cut-off a particular chemistry will allow.


It's not much of a feature creep to add a button for custom number. The midnight solar product does the same for their product line.


Just making a suggestion. The site is pretty nice, if you don't want to fix it.

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Gary Pacey avatar image
Gary Pacey answered ·

Great tool. It would be good to have a variable of the tilt angle, in particular, to derate for horizontal panels on RV's and boats.

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mvader (Victron Energy) avatar image mvader (Victron Energy) ♦♦ commented ·

Hi; yes thats a good idea. In derating; you also do that for selecting the mppt; so opt for a smaller one?


Or do you mean for the graph of expected yield?

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Stefanie (Victron Energy Staff) avatar image
Stefanie (Victron Energy Staff) answered ·

Nice! Thank you.

Cosmetic issue: It is missing the unit (Wh or kWh) for "Forecasted Yield per day per month.

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mvader (Victron Energy) avatar image mvader (Victron Energy) ♦♦ commented ·

Hi; yes thank you Stefanie! To be fixed.

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Mark avatar image
Mark answered ·

In terms of the 'recommended' MPPT option list - sometimes I think that some 'variations' of the same size MPPT may be missing.

As you know many sizes come in 4 'variant' options - BlueSolar TR, BlueSolar MC4, SmartSolar TR & SmartSolar MC4.

It may be 'neater' to present all variants of the same size/general type in a single section/block rather than separately & then give the 4 'variant' options & PN's in the same section/block.

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