Typically a sailboat in Europe sails from one marina to the next, where you can plug into shore power to top up the batteries. In the Caribbean we often sail for six month or more without ever entering a marina. Therefore we need to be completely self-sufficient in terms of power generation.
Our energy consumption is about 120 Ah a day at 12V, or 1.4 kWh per day (compare that to your consumption at home!). Some 80 Ah per day go to the fridge and freezer. The water cooled condensers on the fridge and freezer significantly increase the efficiency of these units. Without them, our energy consumption would have been more. Once every third day we run the water maker to top up the tank. On those days we use an additional 50 Ah of electrical power.
We did not order a separate diesel generator as part of the optional extra's from Hallberg Rassy. This was based on advice from John Neal. Mahina Tiare sails around the world, usually with 8 persons on board, and they don't have a diesel generator. Instead, they have a very powerful second alternator mounted on the main engine.
I don't regret not having a diesel generator. The generator in Hallberg Rassy's options list is a Fisher Panda. From talking to other cruisers we gather that they have more failures than any other piece of equipment on board a sailboat. Besides, generators are expensive and they are just one more item to maintain.
We wanted to order a powerful second alternator with an external voltage regulator as an optional extra from Hallberg Rassy. However, they did not offer this option, because it would void the Volvo Penta warrantee. We settled for a second internally regulated alternator from Volvo. So now we had two 60A, 12 V alternators charging both the starting battery and the house battery.
Two times 60A is 120A. We should be able to replace the 120 Ah we use in a day in about 1 hour right? No! Some 5 minutes after the engine is started the charging current reduces to 40 A. We found this out on the way from Sweden to Holland. The reason is that the internal regulator doesn't force the alternator to maintain its rated output until the batteries reach 14.2 V. And if you would install an external regulator, these standard alternators would soon burn up, because they are not built to generate maximum power for long periods of time. With a charging current of only 40 A we would have to run the engine for 3 hours every day, and more than 4 hours on those days when we run the water maker. This is not really an acceptable solution.
In Holland we replaced the second Volvo alternator with a 90 A rated Bosch alternator and an external regulator from Mastervolt. This increased the charging current at fast idle (typical for charging the batteries at anchor) to about 60 A.
On our trip to the Canaries we were mainly staying in marinas and during the Atlantic crossing we were using our towing generator, which helped to reduce our daily engine running time.
Once in the Caribbean we realised that running the engine for two hours a day is still quite uncomfortable. Besides, it is bad for a diesel engine to be running at light load for long periods of time, especially for a turbo diesel such as the one we have. We needed an additional source of energy.
Wind generator or solar panel. That was the question. Wind generators are capable of making power 24 hours a day. By contrast, a 5 A solar panel makes about 30 Ah per day (i.e. 5 A times 6 hours). In order to make sufficient power, we would need at least 2.5 square meters. The output of solar panels is severely reduced by even a small amount of shading. It would not be easy to locate 2.5 square meters of solar panels where it would not be shaded by the mast or rigging.
I decided for a wind generator. With hindsight this was the wrong decision. Air marine is a very popular brand of wind generator in the Caribbean, although a bit controversial because they are noisy. Just at this time a new model, the AirX was coming on the market which was claimed to be 80% less noisy than the previous model. This is what we bought. With hindsight one of the worst decisions I ever made. We suffered the noise for about 6 months, meanwhile trying everything to reduce the noise. At night we switched off the wind generator, so we could sleep.
Finally we decided to bite the bullet and replace the AirX with a KISS wind generator. This unit is indeed a lot quieter. However, we still switch it off at night because the vibrations from the mounting pole on the aft deck are very audible in the aft cabin where we sleep.
Because we switch off the wind generator at night, and also because anchorages tend to be in the lee of an island where it is less windy, the power from the wind generator is still very disappointing. Of course it all depends on the wind conditions in the anchorage, but typically, we make perhaps 40 Ah per day.
On our way from the Dominican Republic to Bonaire our 90 A Bosch alternator burnt out. Both the stator coil and the diodes were destroyed. It was better to replace it rather than repair it. I bought a 150 A Balmar alternator, together with a new external regulator. The latter has a temperature sensor which is meant to protect the alternator against overheating. The new Balmar alternator generates about 90 A at fast idle.
Despite the temperature sensor, the Balmar alternator has burnt out as well. This time only the diodes were destroyed. They were replaced under warrantee.
Despite the wind generator and the bigger alternator, we were still running the engine too much. Meanwhile I had modified the bimini so that it was a lot sturdier, and also so that it could stay up whilst sailing. Now it presented an ideal surface to mount the solar panels. I installed 3 Siemens solar panels of 110 W each. They are connected to the batteries through a Solar Boost 2000E regulator with Maximum Power Point Tracking. The latter increases the daily power output by some 10%.
Together the solar panels typically generate about 100 Ah per day (more if it is sunny all day). They are quiet, reliable and simply wonderful. Typically we run the engine half an hour to an hour every third day when we also run the water maker. At the same time the cooling water from the engine heats the water in our hot water boiler.
Solar panels and wind generator