Where to find energy for those who live on boat

Lets's find sourses of energy we need for mooring in tropical place with 28-30C during the day time and 24-27 at night. We had this article where there was a discution where we see 1200W per day for1 person, 1600-2000W for two and 3300W with limited AC(condicioner) per day.

Problem with boats, we have very limited space and surface area.

Reasonable installations of solar panels. I have seen three different installations: a. on top of bemini b. on the deck  c. on the side of starboard or portside.

On top of bemini or metal carcas typically there is around 1.5m by 2.5m, which is 3.75m2 could give us around 500W in ideal situation  at mid-day and 300W on different sun angles. Please see how I got this on that page (click here).

Let's assume 2 ideal hours and around 3 hours in less then ideal (60% of max power). That would give around 1300-1400Watt per day.

Deck surface area is even smaller due to dead areas, used by attachments. It is possible to have extra 1-1.5 m2 or another 100W per hou or extra 500W per day.

Sides of boat is not the best in tight marina areas. In an open mooring it could give in very ideal set up around 3m2 on each side, which is around 1000W on each side.

As you can see we could have anywhere around 3000 to 4000 Watt if ALL possible space is used and hull is equiped with side attahements to keep solar panel.

Most likely an avarage boat will be equipeed with 3m2 pannels, wih is around 1300W per day of solar panel worth of power.

But this is the raw power from panels. Then we need to feed this power to solar cotroller/charger and inverter. From Chinese specs it looks very good, but in real life it is 95% efficiency for best charger, 93% or inverter side and about 15% loss during charging battery for losses in chemstry. The real number for inverte is arround 78% efficiency,  92% for charge/loadcontrollers. Also remember the solar controller using power by itself. The lowest side of self consumption is around 0.5W/hr but with inverter connected all the tme it is 2-4W for the best. Tu summirize all said about power losses, I would say it is about 20% for just charging and storing and add 12W loss for just controller stays on. Therefore if you only use DC power and turn off inverter, you should have around 1000W with bemini area. If you add extra 1m2 area on the deck, it shouldbe enough for one person without AC. For two people you will need need extra 600-800W, which can be brought by 2 squeare meter of panel, but  you will have to find a space on the sides. Remember the panels have to be as close as possible to perpendiular angle to sun rays. Leaving panels vertical will only give you less then 40% energy. Please use this caculator to see how angle influence the energy.

Then there is a wind generator. Very cummon and probubly the only one I've seen so far is around 100W/hr in optimal wind condiion. Please do not beive 300 or 400W ratings. In small winds it will barely give you 40W. In mid wind around -100W. High speed 20-30knot will give around 150W per hour at best. So during the day you might get extra 400-1000W in good windy day. This could be wonderful extra energy source to solar. Wind could blow during night, when solar does not exist.

During winters, usage of AC power is not that esential. In summer time we need about 1500W extra per day for air conditionng.

As we can see, boat area does not alow that. The only reasonable extra source of power is gas/deasel generator. WE do not concder shore power at the moment.

3KW diesel uses around 200ml fuel per hour. Therefore to get extra energy for AC we need about 1 hour of diesel generator. Therefore this will be about 6L of fuel per month if you add solar and wind to totall energy equasion.


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