Chief Electrical Engineer Titley bought this book on our little detour to Lymington en route from Aubeterre. It's an excellent book from Fernhurst, my own publisher: https://www.amazon.co.uk/Skippers-Practical-Handbook-Richard-Crooks/dp/0470059710/ref=cm_cr_arp_d_product_top?ie=UTF8
We have been reading it together and have tried to come up with our expected daily electric budget in Ah. We will have a 60Ah engine battery and an upgrade to 4 no. 100Ah AGM batterries, giving us a 400Ah service bank.
We are assuming that the Yanmar 45hp (4JH45) engine's alternator (125A rating) has a 'smart regulator' to charge the batteries efficiently; if not we will need one fitted. We need to know what ampage the alternator will deliver at normal cruising revs (say 2000 rpm). If it delivers say 90A at that speed, then a full bank charge from 50% would take just over 2 hours of motoring, which feels about right?
For days at anchor, we will need an alternate power source, as we are loathe to run the engine in a quiet cove. Given we will be in sunny climes and sheltered (hopefully) from strong winds, solar panels seem to be the obvious choice. We could have flexible panels integrated into the bimini and portable ones to move around if the bimini is shaded. Say, we use 100Ah in a day at anchor (conservative estimate?), we would need to replace that with solar power of 100A x 12v = 1,200W over say an 8 hour sunny day; i.e. an 150W solar panel!
We also need to find out if we can plug these into the same 'smart regulator', but assume we require a separate, specific controller such as an MPPT. We would need flexible panels and need to determine whether 'silicon polycrystalline' or 'monocrystalline' are the way to go.
Maybe: SunPower Flexible Monocrystalline High Efficiency Solar Panel