Mambo
Good job on getting solar array design to cover power needs. A few questions:
-- Is your current vessel's genset and charging system sufficient to keep the batteries topped up if solar slows for a day or two?
-- What is your gensets fuel burn?
-- How big are your loads for hot water, water maker, refrigerators and cooking?
Thanks
I had 2 x 12 V 90 A alternators on the boat plus 4 x 150 Wp solar panels. That set up could not keep the house bank charged if we had a few days of bad weather. The genset is a 6 Kva Cummins Onan, which needed to be used for the heavy load equipment (washing machine, dishwasher, water maker, cooking stove etc), so that was not what I wanted.
The house bank at the time was 12 V 600 Ah.
Also had a Victron Multiplus 12 / 3000 and a Fraron 5 in 1 12 V 3000 inverter charger, but they could not communicate at all. All the battery switches were bypassed, so that you could not isolate a single battery if that would be necessary.
The genset uses about 3 ltr per hour at full load and if I would have to run the generator 24 hours per day I calculated (did not measure it) it would use about 30 ltr per day. Over a 30 day period that would be 900 ltr and with 3200 ltr on board I would use, in a 2 month period, more than half the available fuel for the generator instead of for cruising.
I was unhappy with that whole set up, it was inefficient, dangerous (all the by passes) and when I found battery cables (and other cables) of which the insulation was cracking up it became an easy decision. Everything had to come out, organize it and redo most of the wiring. The electricians then suggested to go up to 24 V, so as to lower the Amps and prepare for the lithium batteries.
My boiler is a combined electrical and cooling water system. When the engines are running the hot cooling water goes through the boiler and the electrical heater is not used. When the engines are off it uses only electricity and that is 5 A at 220 V. Since it is a relatively small boiler, it heats up real quick (appr 20 min from cold to warm, which is 60 degrees Celsius), so total of 1.7 Amp at 220 V, which will be about 17 A at 24 V (roughly) and it is heavily insulated, so does not lose temperature. that quick.
The water maker uses 2500 W at 220 V so that is 11 A or 110 A at 24 V and does 150 ltr per hour. Since you should not use it in a port / marina or close to shore we only use it while underway and then it gets powered via the alternators and inverter. We have 2 x 600 ltr fresh water tanks on board and fill up every time we have the chance in a marina or port. Once the tanks are full we don't need to fill them up for about 15 days. Our water usage is minimal, that is something we learned in the Caribbean, where water is at a premium. So that comes in handy and 2 hours water making while underway gives us 300 liters, which will give us about 3 to 4 days easily.
The washing machine uses 4.5 A at 220 V in a cold water program or 9 A at 220 V during a warm water program. The latter we hardly use, 60 degrees Celsius is max, that is enough to get the sweat out of the sheets and salt out of towels. No need to go to a 90 degree Celsius program.
The cooking plate was 6 Kw at 220 V, was electric, but changed it into a 3500 W at 220 V induction plate, which is 16 A or 160 A at 24 V if used at max. Since I can read the amps while cooking I know we use about 4 A at 220 for about 20 min, which is about 40 A at 24 V.
Instead of the induction plate we do use a 2000 W at 220 V grill plate for cooking most of the time, so that is about 9 A or 90 A at 24 V. Grill plate is on for about 30 min max, which means 45 A. This is the only equipment for which we would be willing to start up the genset.
There was brand new 5 Kw electric oven in the boat, I threw it out and replaced it with a combination microwave. That one uses 900 W at 220 V or 4.5 A, which is 45 A at 24 V. Actual use is perhaps a few minutes each time, so about 2.5 A at 24 V.
Our espresso machine is 1500 W at 220 V or 7 A which is 70 A at 24 V, but is only used about 2 min each time (at 3 times per day), which is 6 min so 7 A.
Fridge 1 is 100 W at 220 V or 0.5 A which is 5 A at 24 V.
Fridge 2 is 300 W at 220 V or 1.5 A which is 15 A at 24 V
Freezer is 70 W at 220 V or 0.3 A which is 3 A at 24 V.
If you leave the doors closed, have them stocked up to capacity (cold bank) the compressor will work about 10 min each hour (actually timed it), so that makes a total of 4 - 5 A at 24 V per hour or about 100 A each day.
The dishwasher uses 900 W at 220 V and 6 ltr of warm water from the boiler for a 20 min program. So that is 4 A or 40 A at 24 V, which is 8 A for a 20 min program. Only use it when the dish washer is full, so no unnecessary use for just a few kitchen utensils.
TV is 100 w at 220 V which is 0.5 A or 5 A at 24 V. Basically only in use during Formula 1 races and bad weather
Stereo is a normal 12 V car radio as well as a 300 W dolby home theatre system, which is 1.5 A at 220 V so 15 A at 24 V. Again, that is only on during Formula 1 races.
We do have 3 air conditioners on board, each of them Dometic, use 1200 W at 220 V, so about 6 A or 60 A at 24 V, but we have never used them. We like the heat, have been living in the Caribbean for many many years and don't use an air conditioner there. So am actually thinking about throwing them out of the boat and getting our storage space back.
That is about the main equipment we have on board. There is some smaller stuff, but nothing major, only in use when we are underway or in very rare situations.
Of course we do change our behavior a bit when bad weather arrives. If we know there won't be a lot of solar energy we will not start up the washing machine, nor any of the other heavy users. We will get to a max of 200 A at 24 V per day, so with 1000 Ah in the batteries we can go 2.5 to 3 days. If necessary we can start up the genset for cooking to save the batteries, but since it does not make sense to remain in a bay during bad weather the engines will be started up anyway during those days to bring us to shelter and then they will recharge the batteries as well. The moment the sun comes back the solar array will take over. At 50 % efficiency they will charge with about 80 A and that means that in 3 hours they have supplied our full daily use and in about 10 hours they can charge the batteries again. Normal sun hours in the Med in season are between 12 and 14 and usually there are hardly any clouds. Shading to the panels is minimal and the panels are divided in 4 groups, each group has a Victron MPPT controller. Each panel is divided in 3 sections, so that if one section is shaded the other 2 will still deliver at max output.
Long answer, but I hope I touched all the subjects.
