Well working electricity on board is one of the most important factors for an enjoyable and comfortable journey, it requires a lot of thinking, planning and unfortunately a lot of investments, so it’s important to do right from the start.
Kerpa sailing between the Canary Islands
Amel SM is a rather “hungry on electricity” she is well-equipped in standard version and many things are automated; electric reef of the genoa and main, electric winches, bow thruster, autopilot etc. etc.
It is also equipped with a washing machine and AC as standard, but this is powered by 230 V from a diesel generator or shore power.
The electrical system consists of three parts
-12 volt system for navigation and communication
-24 volt system for most of the rest on board powered by low current.
-230 volt system for essentially washing machine, AC and watermaker that goes on 24 volts, but we drive it exclusively when we either go for a motor or run the diesel generator.
Set up of our 24 v system.
We have eight 110 Ah 12V Type 31 batteries. Thus, 440 Ah 24 V capacity in our battery bank.
The largest consumers are refrigerators, freezers, autopilot,computer and radar
Electric winches and the electric reefing do not pull much, as they run for a short time only. the bow thruster we only use when the engine is running and the same applies to the anchor winch.
All lighting are led so only a minor consumer.
Instruments and communications run at 12 volts and get their power through a number of 24v to 12v converters, so these draw from our 24 volt system.
At anchor we use roughly 100 Ah 24v per 24 hours
These are numbers in hot climates about 28- 30 degrees C, Fridge and freezer draw more as it gets hotter. When sailing, consumption increases to maybe just over 200 Ah 24v / day, the main consumer are autopilot computer and instruments, as well as the need for radar at night. AIS significantly reduces the need for radar, so clear nights we hardly use the radar, or run it in standby mode so it only sweeps one minute every 10 minutes, all to save power.
When we bought Kerpa, the batteries was charged either by a 60A alternator with a “dumb” regulator or by the genset who feed 220 volt to a 60 A battery charger.
As we try to avoid going below 80% charge rate, we run the genset for about 3-4 times a day for ca one hour, but that is not our “cup of tea”. Anchored in a calm and quiet cove and enjoy nature and silence, or sailing with a glass of wine or a cup of tea in my hand then I do not want the sound of a diesel engine, it fits very badly, in addition, it’s a n other items that that can break and going to need maintenance.
What to do?
We thought a lot about how to solve the issue, water generator, wind generator, or solar cells?
The choice fell on solar cells and it is something that we absolutely not have regretted, the opposite. We have installed a group of 3 solar panels of 150 w in parallel-connection in total 450 W on an arc at the stern, a very good location, as there is not much shadow on them.
Mounting of the arc, this is stainless and quite heavy, there are standard arches from the Atlantic Towers in aluminum that weight less and probably cheaper than making one. Have seen them and they look very good and the owners have been happy. The actual solar panels are quite heavy also, so it can be a lot of weight in the stern, something to think about.
But it looks good and work excellent
We also have a group of 4 times 100 W flexible solar panels in parallel, two of which are on the rail and two on the biminin work well, but not as good as those on the arc as they get less shadow on them.
Flexible solar panel fixed only with Velcro,. Has been working for about a year now even though we have encounter conditions with 40 kn upwind an waves flushing over Kerpa and the bimini. A number of Canvas makers did not want to install the panels, they said it will chafe on the cloth, you get problems with moisture etc. Finally we insisted, told the man to put an extra layer of cloth under the panel, when he was ready and we together put the panels in place he admitted this was not bad at all. Now after a year we have to change the Velcro on the panel part, a minor issue.
The Panels on the “rail” in series with them on the bimini, works well they give about 35% of the average daily production, nominally they should give 47%, but more shadow hence the lower average output.
Both groups have their own individual MPPT regulator from Victron, to whom we have connected a “clock”, which provides all the possible data needed and a little bit more, so no problem to have full control on how much going in to the batteries and the charging state of the battery bank.
We only se minor interference between the two MPPT regulators only when the batteries have a very high charge rate over 95%, then one group can go down to sometimes zero A, so no contribution at all, but otherwise, both groups will give full contributions.
On sunny days it’s not uncommon for us to get over 120 Ah 24v and we have noticed 147 Ah. Even cloudy and rainy days we can get in 60-70 Ah as the sun shines through now and then. The average is around 100 Ah / day, so we have “100%” in our batteries somewhere between 13:00 and 15:00 depending on the weather and consumption when we are at anchor.
We have noticed a little unexpected power thief, it’s our laptop, for a few weeks we had a little tighter power consumption control and discovered to our surprise that if we turned off the computer when not in need! (otherwise excellent anchor watch in the open CPN) it significantly reduced consumption, would guess we’re saving about 10 Ah a day. Now with 850W solar cells, we never need to run the genset to charge our batteries a normal sunny day
Otherwise, we have upgraded the electric system with a combined charger
/inverter from Victron, providing 70A 24v and 3 kw 230V, We kept the 60A old charger so when we running the genset we use both chargers, they give together ca 95A for about 10-15 minutes then the old 60 A go down in amp, but when running the water maker who draw 18 A, our total consumption is maybe 30 A then both charger contribute. We have a manual temperature monitoring of the batteries, a regular outdoor/indoor thermometer to see if the batteries get extra hot, but I only notice minor differences between the temperature in the battery compartment and the rest of the boat say 2-3 degrees C