Technical Steca Solsum 6.6X control panel

[Robert56]

I found a blown fuse on my Steca Solsum 6.6X' solar panel control unit. I replaced that and it is now charging the leisure battery in my Fiat Ducati camper van. However the charging voltage across the battery terminals is 15.3V which I believe is excessive. When I removed the feed fuse between the 6.6X and the leisure battery, the battery feed voltage rises to 19.75V as measured at terminals on the 6.6X.

Does anyone have experience of this solar power controller and can advise whether the unit may be faulty?

 

[NeilDD]

Whilst I do know much about the Steca range of solar controllers a quick google shows that depending upon setup the same controller can be used for both 12 and 24V.

It is not unusual for the output of the solar panel (Voc) to be up to 25V, and the controller regulates this down to your nominal 13.2 V for lead acid batteries and 14.7 for Lithium LiFePo4 types.

If you are confident with electrics, I would look at putting in a modern MPPT controller from someone like Victron which is almost plug and play.

If you can provide a little more info on;
1/ Solar panel size
2/ Make and capacity of your habitation battery
I can make a better recommendation

Cheers
Neil

 

[Robert56]

Thanks Neil
I bought the van with the Solar already installed but I’ll have a hunt and see if I can find any info on the solar panel.
I have just fitted a new habitation battery which is a Varta LED95 so 95Ah.

The 6.6X is rated at a maximum current output of around 6A

 

[Robert56]

I can't find any spec for the actual solar panel but my local caravan place said I should be fine with a 10A controller.. Any recommendations?

 

[NeilDD]

Hi Robert,
The gold standard would be Victron and Renogy, but their around 60-80 quid
As long as you buy an MPPT controller you should be fine, such as your caravan place.

Personal preference would be a Victron 75/15 (upto 75V input at a max 15A) on eBay item number 303000125827
Also gives you the ability to monitor the controller via Bluetooth and the Victron App

Neil

 

[Robert56]

Thanks for your advice. My local dealer fits the less efficient EpEver 10A PWM Controller - VS1024AU. They are cheap but do you think I should avoid this model?

 

[NeilDD]

Hi Robert,
Just had look, and that model is a PWM controller, which means that you will get a slightly lower output compared with an MPPT controller.
But for only £24 on Amazon it will keep you going for a few years, until you need to upgrade.

I'm currently upgrading my system to 500W of panels and a combined battery to battery system and MPPT 50A controller for more off grid use.

Neil

 

[Robert56]

Thanks Neil
Does any excess power on the PWM controller get dumped as heat? I ask because the old controller is in a cupboard and not easy to change without a major rewire.

Robert

 

[Robert56]

Ah! And I just noticed that the Epever unit is positive ground controller. Can I use this in my camper van where battery negative terminals are connected to chassis?

 

[NeilDD]

Hi Robert,
Yes excess power is dumped as heat, hence the large heatsink on the rear.
Don't worry about the term common positive, its nothing for you to worry about in this application, and should work fine

 

[Robert56]

I bought the 10A version of the Victron.