a typical 120WATT SOLAR PANEL will only produce 5-6 AMPS DC Current when in high sun. This then is even more dropped by the PWN Controller when it produces the smart mode DC Voltages of 14.4-13.6-13.2... This is not alot of DC Charging current coming from a single panel in high sun. You parasitic drains associated with your trailer battery setup is usually higher then 2-3 AMPS DC current. Then just leaving one lamp on all night does you in...
A typical deep cycle battery requires the correct sequence of smart mode DC charging voltage and have the capacity of 17-20AMPS DC current if you want the battery to recharge from its 50% charge state to its 90% charge state. This is based on the smart mode DC Voltages listed above. A lower DC Current will still work but it will take much much longer.
You need to look at the Lance provided solar panel and tell us what its WATTAGE is and model number so we can tell how much DC VOLTAGE and DC Current it will produce when in high sun.
Then you will want to know what your battery load is so that you don't draw more current then the solar panel is producing.
Solar panels are not the great thing alot of folks make them out to be. For us they would only be used to keep a battery bank topped off with no or very low parasitic current drain.
You will need several panels in parallel to come up with the 17Amps-20Amps of DC Current for each battery in your battery bank if you want to get recharged in a typical three hour time frame.
Typically the solar panels put out the higher DC current in a six hour high sun time... The rest of the time is low DC current and of course after the high sun goes down you will get zero DC current from them...
This is somewhat different for each install but basically correct on what to expect...
I am still learning how to live off my battery bank and haven't got to the solar panels yet to keep them topped off... My first goal was to beef up my battery bank and make my trailer as GREEN as possible then go for the solar panels. Since we have a pretty high DC current usage our biggest solar panel bank would not produce enough DC current based on the roof size area. This requires me to run a 2KW generator doing the first initial high current demand until it starts its normal tapering off. Then the solar panels would complete my charging during the rest of the available high sun day.
Kinda depends on where you camp on the east side of the US or the West side. slightly different rules apply...
Its all a learning process...
Typically two wires from the solar panel feeds the solar controller and then two DC OUTPUT wires feeds the battery bank. The controller takes the generated solar DC OUTPUT and sends smart mode DC charging voltages to the battery bank. Using the lower DC Voltages from the solar panels will eat into the output current when developing the correct charging volages from the controll... You will find solar panels are not as efficient as one might expect. using a PWN controller I think the 120WATT panels only really give you around 80WATTs of smart mode control voltages when in the high sun.
Hope some of this helps...
Lots of info on GOOGLE SEARCH on how all of this is suppose to work - also lots of diagrams as well...
Roy Ken
My Posts are IMHO based on my experiences - Words in CAPS does not mean I am shouting
Roy - Carolyn
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