My original system consisted of 30 amp shore power hookup, Onan 9.5 kilowatt generator, 30 amp power converter from 110v to 12v with battery charger, and two deep-cycle marine/RV batteries.
First thing I discovered was that my batteries were not holding a charge long enough, barely one day. Upon inspection I discovered that one of the two batteries was completely dry. I added water but it was shot. I found that it was time to replace the batteries and proceed with my plan to upgrade the electrical system.
My master plan is to have a completely self contained system and not have to rely on shore power. The generator is noisy, vibrates, produces exhaust, and is down right unpleasant. My solution is to build a solar power system for my rig. Some of the items I need to put into the system include the solar panels, storage batteries, charge controller (to regulate the current flowing into the system and batteries so I don't over charge the batteries) and a power inverter (to convert the 12 volts direct current into 110 volts of alternating current in order to run my computer, TV, breadmaker and various other household appliances.
The storage batteries were the first thing to add to my system. After a bunch of research I found that the best type of battery for this type of system are true deep-cycle golf cart batteries. The manufacturer most recommended was Trojan. I decided to go with the Trojan T-105 it is a very popular and available battery. These batteries are a bit taller than regular RV batteries but hold a lot of juice and last twice as long.
My next decision was to figure how many batteries I would need. A number of factors go into this decision such as how much electricity will I need between charges, how they are going to be charged, etc. In order to start calculating my electricity usage, I needed to convert everything to a common unit of measurement. Most appliances are rated in amps, but then you have to figure in the voltage, since there is a big difference between 1 amp/hr 12volts and 1 amp/hr at 110 volts. So from here on in I will break everything down to Watts/hr which is basically Volts times Amps. The Trojan T-105 batteries are rated in amps; they hold 220 amps each and are 6 volts. I would need to buy them in pairs and wire them up in series in order to connect to my 12 volt system.
I decided to go with 4 batteries to start of with. That calculates out to 880 amps at 6 volts or 440 amps at 12 volts. When you multiply them you get 5280 watts/hr. Now in order to get the greatest life out of deep cycle batteries you do not want to discharge them lower than 50% so the usable watts between charges would be 2640 (but I do have more available in an emergency). That seems to be a reasonable amount but I have to measure my energy use to see how well that works. I also chose that number of batteries due to the number of solar panels I plan to use. This first system will consist of two 120 watt panels. There is a rule some solar designers go by to calculate battery capacity to solar panel output. It is said to have 1 amp of storage for every watt of panel output…. There we go with mixing units of measurement. The conservative approach is 1 amp of storage for every watt of output, this guarantees full charging when the weather isn't so clear and there is reduced output. The way I figure it is 2 panels will have an output of 240 watts in one hour, if there are 8 hours of good light then the total output will be 240 * 8 = 1920 Watts. This means I need to try and keep my daily usage down to 1920 Watts per day or I will have a deficit in my charge for the day.
I will start with this and see how it goes; I can always add more panels and batteries later in the future.
My next step will be to add an inverter so that I can use all of my 110 volt appliances.