Solar and Battery advice please

I am just going through the same exercise.
I have bought a genuine mppt controller from photonics universe to replace a blown cheap chinese PWM unit.

12V solar panels charging kits for caravans, motorhomes, boats, yachts, marine.

It only diverts a small trickle charge to your engine battery. It can be used as for either a single or dual battery set up.
They are only a little more expensive than pwm controllers. Be very careful many chinese ones are sold as MPPT but just use PWM internals.

Any controller cheaper than this is likely to be a PWM unit and will not have the benefits of MPPT.
I intend to put my 20v SPs in series.
 
Your battery choice may be constrained by available space, but I'd go for a smaller engine start battery - whatever can deliver enough CCA to crank engine. Spend the difference on the biggest house battery you can fit in. Look at Yuasa Commercial YBX3640 and others in that range. Or Exide ER350/ER450.
 
Parallel is better unless you can guarentee the panels won't get any shade at all, i.e. mounted on a frame above the pushpit etc. Other wise if one panel gets some shade it will negate the other panels output and you lose the benefit of them being connected in series.
It takes very little shade to half the output of a panel unfortunately. Not much you can do about that for the average family 25ft boat unless you have the space to mount them as mentioned high up on a frame. The big full time cruisers do this.
 
Not sure if that should the case if your using an MPPT , we did a few test while lock down on a friends boat and found shading part of a panel while connected in Series did very little ,
It didn't matter if we shaded the end of the middle of the panel .
 
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