The basic idea of changing to solar was that we don't want to have a generator running while we are lying in a pristine bay. We don't want the noise, we don't want the fumes, nor do we want to bother anyone else with that.
On top of that I have the rule that 1 person has to be awake when the generator is running. There is no chance that everybody is asleep when the generator is running, it is not going to happen. If something would happen to the generator we would not notice it.
And lastly, not spending fuel on the generator would mean more fuel for the engines and that means more range on the boat. Here in the Med that is important, there are hundreds of islands to visit and not all of them have a fuel station.
Before I decided on the amount of panels I put all the electricity users in an Excel sheet. Figured out how many amps they would draw and how long I would use them during the day and during the night. Thus I came to the required peak amps, the amps during the day and the amps during the night.
That gave me a good indication of my power requirements and based on that I calculated how much solar I would need. I figured an efficiency of the panels of 50 % for about 8 hours per day, but now I realize we are more at 75 - 80 % efficiency which is great.
The battery bank was calculated at 3 x daily use with no solar, so that came to about 1400 Ah. The chance I won't be able to charge the batteries for 3 days is almost nil, since I can charge the batteries via the generator, shore power, alternators and solar panels.
In other words now we don't really need the generator anymore, it is just a back up and that is what we had in mind all the time.
As for the position of the panels I contacted Defever in Taiwan and they told me not to put rigid panels on the bimini. Stability would be affected negatively, so that was out of the window.
Then I realized we had the dinghy lying on the dinghy or sun deck, so taking the dinghy off and replacing that with a large frame on the stern would not make a difference in the weight and balance. It would also add shade to the sterndeck, which was perfect so had it welded in Greece. The panels fit perfectly and there is no obstruction from the sun.
The other panels were intended to be 2 on portside and 2 on starboard side, but that did not work out. So now it is 2 on port, 1 on starboard and 1 in the back of the sun deck. Deck is large enough so the loss of some space for a panel does not hurt us.
The panels on the side are hanging vertical while we are in port or underway when there is wind. But on anchor or underway in light wind we raise them to horizontal and thus we have all the panels working fine.
Here in Greece / Turkey the wind is basically always coming from the NW to NE which means the stern is always turned towards the sun and with no clouds whatsoever we have the full sun from 8 in the morning until 5 to 6 PM, so 2.5 Kw per hour. After and before that it goes a bit down, but we normally always have around 1 Kw per hour.
In all we are very happy with the result and it actually worked out better than expected, but perhaps my calculations on the efficiendy were a bit conservative. However it is better to have above expectations than below expectations.
