On 26 Aug 2019 14:22:34 +0100 (BST), Theo
wrote:

T i m wrote:
Talking to the owner of a mostly electric narrow boat the other day,
he ditched his solar panels completely (as they failed) as they were
not really able to contribute much to the solution, even on a 'good'
day.

They may have their place, but not even as a UPS on a sunny day
apparently? ;-(

Narrow boats are, well, narrow,

Yeah, but they are about as wide as a reasonable Solar Panel and often
60-70' long. ;-)

and moorings are often shaded by trees.

That is true.

That wouldn't be my first site for a solar installation.

No, but many do have quite a few panels so I'm guessing they mush have
some use, if only / mostly in the summer and for recovering *some*
charge in the Aux / Main batteries?

Better to have the
panels on land and feed in the power to the boat via a wire with a mains
plug on the end.

Again, you are right of course [1] but that sorta defeats the whole
'mobile / off grid home' thing. ;-)

In this case the boat is equipped with a 600cc twin cylinder diesel
engine that is run high up in it's efficiency curve when needed to
(only) charge the batteries.

As a spinoff of that the engine also provides underfloor heating via
it's cooling circuits.

The interesting bit is that he was saying that the LA batteries really
needed regular (fortnightly) 'balancing' and if running off grid, that
mean running the engine / generator at less than a full load for
several (~5-6) hours. If a mains power socket was available that is
much more efficient of course.

As an alternative to using the generator for the balancing /
equalisation / de-stratification stage, he was considering using some
form of Lithium battery or even SuperCapacitor, as they could use the
spare power after the end of the main battery bulk charge phase and
neither would need much balancing?

I've not read / absorbed all the tech details on his handout yet but
he was also saying the boat was too heavy and he will have to remove
some ballast. I was surprised to learn that the batteries weren't part
of that ballast (in the bilges etc) but were in the main accommodation
area as such?

So his was a 'diesel electric' (with batteries) in a similar way a
diesel electric train or ship might be, whereas some other hybrid
boats could drive the prop with electric motors or the IC engine
directly. Apparently that causes a big compromise because of the revs
/ torque available and he the size of prop required (bigger for
electric). But why couldn't they drive the big electric prop from the
IC engine via a reduction gearbox of some sort? Reduced efficient
(losses in the gearbox) possibly?

Cheers, T i m

[1] Someone was asking me about the idea of a solar powered, battery
stored, portable waterpump for allotment use. The water is delivered
to IBC tanks via some plumbing (and water butts from the rain etc) but
needs to be delivered to the plants manually. I suggested that maybe a
leisure battery and suitable low power pump (possibly submersible)
could do the job but like you, suggested the panels might be on top of
a 'docking shed' or some such?