Mppt

Jules62

Full Member

Messages
6
Hi I have 2 x 250watt mono solar panels I am hoping to get 2x 230ah agm batteries. Can anybody help me with the correct size charge controller? I am going the Victron way and I’m not sure which one to get I was thinking either 150/35 or 100/50. I haven’t a clue so looking forward to your valuable input.
 

wildebus

Full Member

Messages
3,300
the 100/30 will support 440W
the 100/50 will support upto 700W. I wouldn't bother considering the 150/35 for your panels - no benefit for your setup.

the 100/50 is around £90 more than the 100/30. I am mentioning the 100/30 as you rarely get close to 80% of the rating so that controller would do just as good a job for the majority of the time if you were budget-limited.
 

Jules62

Full Member

Messages
6
Thanks very much I’ll get the 100/30 I just thought 500w would have been too much.
 

Full Member

Full Member

Messages
4,382
Thanks very much I’ll get the 100/30 I just thought 500w would have been too much.

It might be worth checking the maximum output voltage of your panels, Jules. The 100/30 is rated at 100V maximum, so you may need to think through whether to connect your panels in parallel or series in order that the controller isn't over loaded. For instance, my panel has an output of 65V so if I had two such panels I'd have to connect them in parallel (65V maximum output), not series (2 X 65V =.130V maximum output).
Dave (Wildebus) has posted lots of information on this topic and you may want to look back through his posts.

Colin 🙂🙂🙂
 

Full Member

Full Member

Messages
4,382
Above is the label on the back of the panels do you think 2of them would be ok with the 100/30 mppt.

The Victron 100/30 can cope with two of the panels you've indicated, whether you connect them in series and have a maximum output of about 28V and maximum current of 13.2A or connect them in parallel and have a maximum output of about 14V and a maximum current of about 26.4A.
But David (Wildebus) will hopefully be along presently and complete the picture.

Colin 🙂🙂🙂
 

wildebus

Full Member

Messages
3,300
Those panels will be fine whichever way they are connected, as Colin has said.
I would be inclined to cable up in parallel and use 6mm2 solar cable for best effect.

What will happen if they were to put out more than 440W (the nominal maximum of the controller) is that the output current just gets capped. you would find on days lucky enough to get good harvesting is that the controller will really be able to put out a bit more than quoted anyway :)
 

Jules62

Full Member

Messages
6
Thanks very much for all your help I think as I’ve already got 4mm2 pv cable I’m gonna bite the bullet and get the 100/50 controller and wire the panels in series and I hope I will be within all parameters then. Thanks again all you kind knowledgeable people.
 

wildebus

Full Member

Messages
3,300
Thanks very much for all your help I think as I’ve already got 4mm2 pv cable I’m gonna bite the bullet and get the 100/50 controller and wire the panels in series and I hope I will be within all parameters then. Thanks again all you kind knowledgeable people.
4mm2 will still be fine either way (y)

Remember to shop around for the controller. As a full member you get discount off the OnboardEnergy price for these as well as money off the Alpha Battery Victron kit.
 

SquirrellCook

Full Member

Messages
426
How the laws of sod mess with your efforts.

Brilliant sunshine and your batteries are charged.
You’ed spent all day minimising your consumption due to poor weather, then as it finally goes into absorb the sun comes out and you can’t use the current.
Solar harvesting can be fun! If the weather doesn’t do as you’d like.
I think if you can manage it, 5 days of safe battery capacity should stop you spoiling your family’s holiday.
And remember even on dull days you can still harvest a little.
 
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