if you have a problem with shade on the coachroof, I would suggest looking at 2-3 smaller panels instead of one larger panel.
Thanks, that's a good idea. The whole issue of where to site the panels is a tricky one. The boat has no pushpit to hang them off as lots of people do. The mooring is on a tidal river that runs pretty much north-south and, owing to its latitude, the sun is always to the south. As the boat swings with the current, the existing solar panel on the forward hatch is either in good sun or shaded by the mast. A panel on the coach roof is almost always going to be in some shade from the boom, and I think even splitting it and having 2 panels, neither would be in full sun for much of the time (there are hills both sides of the river).
I'm therefore wondering if it would not be better to spend the money on the smart regulator for the alternator (instead of the additional solar panel(s) and regulator(s)). I would prefer something a bit more environmentally friendly than running the engine, but if an almost constantly shaded panel would not contribute much power anyway, perhaps it would be better to try to maximise the contribution of the alternator.
That would make the setup:
- batteries as per original post
- existing small solar panel but perhaps with mppt controller
- alternator with smart regulator
- both the above connected to house batteries
- echo charger to keep crank battery topped up