What size Victron MTTP should I get?

[Pezz]

So you clever lot can someone help me work out what size mttp to get? In my van I've currently got a Ctek D250se that the solar side has failed. I think the failure has come from the solar panel being 23.7 VOC and the Ctek will only accept 23. Panel is a 200w. I'm not sure this is the exact model but its pretty close 12V solar panels charging kits for caravans, motorhomes, boats, yachts, marine

The alternator is still charging the leisure battery which is a Lifos 68. So whilst that still works from the alternator I am thinking just get a solar only charger with the view that at some point I'll get a new stand alone DC-DC only charger. Anyway I've been looking at getting a Victron MTTP but not 100% sure about the codes on them and which would be the right size with the panel I already have - the 100-30 seems big and possibly excessive - do I need more than a 20 so a 100-20 or would a smaller 75-15 work?

My leisure set up is pretty standard with the main draw being the fridge other than that its led lights and charging mainly phones - no inverter or anything like that. Solar required to keep the leisure battery topped up to keep the fridge cool whilst parked up and not plugged into a campsite. Just in case that helps guide the advice

Any help greatly appreciated

 

[TallPaul_S]

First number is the max voltage of the panel it can handle, which for your 23voc panel is fine for pretty much any Victron MPPT.

Second number is the maximum charging amps - take this and multiply by the charging voltage (let's say 13.5v for LiFePO4) and a 15a MPPT will let you use 202w of power from your panel.

So, anything above a 75/15 will be fine for you. You can go bigger - the 75/15, up to the 100/20 have the same footprint but just different heights with bigger heatsinks. The 100/30 is the next size up but that's complete overkill.

You could go for a 100/20 like I have, in case you upped your panel size at any point.

I'm actually using a 305w panel and the 100/20 can only use about 270w max, that's called over panelling and it means the panel will hit the max wattage during peak times but I'll have more solar, earlier and for longer whenever it's not peak sunshine (which is 90% of the time!).

 

[Pezz]

First number is the max voltage of the panel it can handle, which for your 23voc panel is fine for pretty much any Victron MPPT.

Second number is the maximum charging amps - take this and multiply by the charging voltage (let's say 13.5v for LiFePO4) and a 15a MPPT will let you use 202w of power from your panel.

So, anything above a 75/15 will be fine for you. You can go bigger - the 75/15, up to the 100/20 have the same footprint but just different heights with bigger heatsinks. The 100/30 is the next size up but that's complete overkill.

You could go for a 100/20 like I have, in case you upped your panel size at any point.

I'm actually using a 305w panel and the 100/20 can only use about 270w max, that's called over panelling and it means the panel will hit the max wattage during peak times but I'll have more solar, earlier and for longer whenever it's not peak sunshine (which is 90% of the time!).

Thanks for that - perfectly explained and now I know - I think I'll go 75-15. Amazon here I come