Jean-Luc Hamot avatar image

Priority to solar on a boat where ESS is not possible, using MPPT and keep batteries 100%


I have a system with 2 MPPTs, Quattro 5000 24V 50/70 and Color Control GX.

When I connect to the shore, I want to use energy from the solar panels in priority, and complement with the grid. I do not want the batteries to be used at all, i.e. no discharge of the batteries.

Using the Keep Batteries charged mode would be great, but ESS is not possible on a boat (why?) and I've no anti-islanding material. Using hub-1 v2 assistant only use battery voltage and will permit batterie use. Virtual switch is not enought intelligent. Etc...

If you have a solution for a boat, it would be welcome !
Thanks in advance,


ESSDVCCvirtual switch
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What type of batteries are you using?

12 batteries Victron GEL AGM 12V/220Ah. System in 24 V.

2 Answers
JohnC avatar image
JohnC answered ·

Hi Jean-Luc. The portal access does help, thanks for that. And I asked for your batt type, just to ensure no exotic bms is in place..

I like the 'kiss principle'. If no need to complicate it, don't. Consider this...

Set your Quatro charger to (say) 25.6V, both Absorb and Float settings. So your batts won't discharge lower than that, and the shore not charge higher. A 'neutral' level (that you could experiment with, especially if your bmv is tuned in correctly).

Set your mppt's higher than that, so they'll have priority while the sun is up. But not too aggressively. You're not daily-cycling your batts, so no need for that 28.8V Absorb. Maybe even as low as 27.0V for an hour in Absorb, then to a 'maintenance level' Float of 26.4V.

Any ac loads while the sun is up, the pv should step up to cover them, and after dark the shore will maintain at least a 'standing V' on your batts.

ESS, especially with no anti-islanding, isn't welcome on the exposed male pins of a shore plug, where ac voltage can feedback, even if only for seconds.

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Thanks for your response!

In fact, solar panels are already used to charge batteries when sun is up (default behavior). So I don't know if it will be suffisient.

You said "Any ac loads while the sun is up, the pv should step up to cover them", but I don't inderstand why? There is no policy here to tell not tu use the shore but the inverter...

May-be I would prefer an "official" solution with an assistant or someting like that, because I don't know if I'm capable of modification like this (voltages) without making errors.

Understood concerning the shore plug!

PS : I've a BMV-700 in addition to the Color Control GX
PPS : Function DVCC is activated

Yeh, the 'policy' is within the V settings. Let's say we use my V suggestions (the levels of which I never intended to be cast-in-stone) as an example. The shore cannot charge above 25.6V, but when the sun is up, the mppt's can, and will, up to their higher V setpoints. A load coming on that may (try to) lower Vbat, will wind up the pv until that V is either satisfied or the pv runs out of steam.

But the shore charge won't come on until Vbat is < 25.6V. Your 'keep batts charged rule'.

And yes, I've seen you've a GX and a BMV. All good, but if you want to use (say) SOC, the setup of something more sophisticated will be much more onerous than changing V's.

The V's in your Quattro's charger are easily changed via VRM's Remote VEConfigure. The mppt's maybe by extra (bluetooth?) kit, but you should lower those anyway with non-cycling batts, where I think you're pushing them too hard..

But come back, happy to continue the discussion..

In fact, I think I expected a solution which will not use the battery at all. Say, transfert solar energy "directly" to the inverter, and complement with the grid if needed, without waiting for the V to decrease.

Now the behavior is reverse, grid is used, if needed the inverter is used (poor shore current or PowerAssist), and batteries are charged by solar at day and grid at night.

However, one day I'll probably try your solution. Except if you find another way from now ;-)

Concerning the float and absorption voltage, they are between the preconisations of Victron (Absorption 14,2 - 14,6 and Float 13,5 - 13,8).
I have those settings :
Stop after excessive bulk checked
Storage mode checked
Use equalization (tubular plate traction battery curve) unchecked
Charge curve Adaptive + BatterySafe
Absorption voltage 28.80 V
Float voltage 27.60 V
Charge current 90 A
Repeated absorption time 1.00 Hr
Repeated absorption interval 7.00 Days
Maximum absorption time 8 Hr

May be I could lower Absorption to 28,40 V and Float to 27,00 V ?

Have a good week!


JohnC avatar image
JohnC answered ·

Aaah, ok. I've misinterpreted you a little. Apologies.

You could look to Virtual Switch (ignore ac). There's a thread here on it (link too):

You *may* find your batts get a little 'light exercise', but if set up carefully should only be at the very top end, and probably better for them anyway. Take a look-see.

My other offerings still stand though. Use as you will..

Re the 'aggressive' charge algorithm, Victron actually have certain kit that can determine when 'storage mode' is warranted and apply it as needed:

Worth reading the (brief) reasoning for that feature. Both your chargers should be configurable to do much the same.

Take care 'overdoing' your batts, they'll last longer if you're gentle with them.

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No problem. My "french" english does not help!

I can't use VirtualSwitch as I have assistants to cut AC-out-2 below 50% SOC. Anyway I think this is not exactly what I want ...

I fact I don't want to drive a relay. I want to have AC-in as PowerAssist to the solar panels, instead of batteries as PowerAssist to the AC-in ! But this is ESS, and I can't use it ...

Thanks for the links. I will check MPPT configuration to follow the instructions.