I've about decided to ditch the useless Rutland
914i wind generator
, which I have not been able to get to make useful power.
I can fit a solar
panel (or two) on a frame over my davits
. I have wanted to avoid this, but nowadays I am starting to not see any alternative.
The primary mission is this: boat lives on a mid-river mooring
with no shore power
. When I cruise
, I don't stay in marinas
very often. So we are largely autonomous with power. I have a low-speed, heavy-duty Kohler 6.5kW generator
driving a Victron Multiplus 70 amp (by 24v) charger
; plus the main engine
has a jumbo Leece-Neville school
putting out 110 amps at 24 volts. All this charges 420 amp/hours (x 24 volts) of Trojan batts.
I leave the boat for a month at a time on her mooring
, as I live in a different country from my boat. As a result, the batts live their lives in a partially charged state, which is not good for them (for lead acid, anyway).
So if I have solar
putting out usable power (unlike the pathetic Rutland wind
turbine), I will come back to my boat to find fully charged and happy batts, unlike today's situation. Besides that, I will cover some of my consumption
on the mooring and on the hook, and while sailing.
Sounds like a good deal. However, I am having some trouble thinking through the sizing. I need 72 cell panels
for a 24v system. I have been looking at the Panasonic monocrystalline ones -- 240 watts each. I could theoretically put two of them on my davits
, as two would roughly equal the beam of my dinghy
, but this would be quite a bit uglier (I mean still
uglier) than a single
panel, I think. On the plus side, they would be wired in parallel, so this will give useful diversity in terms of shading.
But according to midsummerenergy.co.uk, I can only expect a little less than one kw/hour a day from one of these 240 watt panels
on a typical sunny summer day in the UK, which is only about 10% of my battery
bank capacity, and only what my diesel
genset can put into the batts in 40 minutes or so.
So doubling this to 480 watts and 2kW/hours per day doesn't seem like it will really change my generator
runs all that much -- we use quite a bit of power on my boat.
So maybe on the contrary I should find a smaller panel and not expect that much contribution to consumption
, just keeping my batts topped off when away?
What do you solar wizards think?