Hi Sauntress,
just some info that I beleive you require to answer your question. I totally understand that you wish to operate a very simple
electrical system BUT regardless of this it is my opinion that you cannot estimate your solar requirements or for that matter your
battery requirements until you actually know what your exact
power requirements are. Yes there has been some excellent information given here in relatioint to
solar panels and batteries but neither address the actural issue of how much power do you use or actually require.
For example if you are going to use nav lights and are changing them to LED. My nav lights on a 12 metre boat consume approximatley 0.25 Amps per hour (0.25 amp/hours) If we base darkness as being approximatley 9 hours then during that time you would consume 2.25 Amphours (current multiplied by time). If your
compass light is only using 0.1 amps when used we then multiply this by the 9 hours of use and come up with a figure of 0.9 Amp/hrs consumed. If this is your only
consumption then add them together IE 2.25 plus 0.9 = 3.15 amp/hrs use. It can than be expected that your solar panel will be required to imput at least this amount of power during daylight hours but also the battery must be large enough to accept the loss and then be able to be charged during that time to replace what has been consumed.
I then read that you were talking of installing a Short wave
radio, BIG power drain. When on but not transmitting you cosume power. You MUST be aware of your radios power
consumption when on and also when transmitting to
work out how much power in total you have used. An
inverter also will consume power when in standby mode and have a drastic effect on your power source if not monitored.
Working out a boats power consumption is pretty straight forward and tables can be found on the
internet to assist you. Before you do to much more Please
work out not only your boat
current power consumtion over a 24 hr period but also what it may be with the
installation of a
radio etc in the future. It will assist you greatly determining exactly what you require. On our boat I worked out our
electrical demand was approximatley 120 Amp/hrs per day. This calculation was based on the use of the boat with auto
helm, fridges, chartplotters, radios etc during a 24 hour period.
Sorry to be so long winded but it is very important. Also remember that solar is dependant on the sun, yes I know sound silly
but cloudy days on end will have a huge impact on the ability of your
solar panels to charge at full capacity so allow for days when you cannot get full charge in..
I hope far more elequent and more knowledgable speakers can explain this in easier terms than I have.
Greg H