17 volts solar panel

[axis11]

My job is mostly on mechanical works. I know very little about solar panels. I've learned a lot on this forum. Pls. dont get tired on helping people like me to learn.

All of the panels I see is made to have an average otput of 18v. Some charge controllers reduce this voltage and increase the output current. If I make panels with 17v or 16v output, I could use the extra cells to build more panels and increase total current output. Will there be significant voltage drop if im having 50% light intensity or a partly cloudy day up to the extent that the voltage will not be enough to charge the battery? What is the most efficient voltage for charging my 12v battery via the controller assuming the voltage entering the controller is kept constant?

By the way, my contoller is a PWM (I think).

[Sunking]

All of the panels I see is made to have an average otput of 18v.

You are talking about panels made for 12 volt battery systems. Grid tie panels are much higher voltage. As a genneral rule of thumb panels made for battery systems are 18 volts for every 12 volts of battery.

Some charge controllers reduce this voltage and increase the output current. If I make panels with 17v or 16v output, I could use the extra cells to build more panels and increase total current output. Will there be significant voltage drop if im having 50% light intensity or a partly cloudy day up to the extent that the voltage will not be enough to charge the battery? What is the most efficient voltage for charging my 12v battery via the controller assuming the voltage entering the controller is kept constant?

Ok this is where is gets somewhat complicated. There are 2 basic types of charge controller Series (PWM, and MPPT.

PWM is the most popular but very inefficient with 66% being best efficiency. There main handicap with any series typr controller is INPUT CURRENT = OUTPUT CURRENT. All they do is regulate voltage in a series fashion of a resistor using a KISS analogy

MPPT controllers is a true DC to DC buck-boost converter. The efficiency can be as high as 96% on average low 90's. With MPPT INPUT CURRENT does not equal OUTPUT CURRENT. In most case cases output current will be higher than input current assuming input voltage is higher than output voltage.

In addition to using MPPT controllers you are not locked into using lower voltage panels on battery systems like PWM controllers. You can use higher voltage panels to lower currents thus smaller less expensive wire between panels and controller.

[axis11]

You're right, im dealing with 12 volts system.Originally my purpose for buying a 12v to 220v inverter was for providing 220vac during camping trips using a car.It was just lately that I've stumbled on this solar stuff. To reduce further investment, I utilized the 12v inverter and purchased items which would match the items I have. I understand that it is needed to have a higher voltage on the panels compared to the battery in order to have charging. I will assume from what you said that 18v is the optimum charging voltage. Charging current from my 3x6 cells/panel remains 3.6 amps.pls correct me if im wrong (I always am). I can still charge the 12v battery with voltage as less as 14v. Was the extra voltage from the panels intended for voltage drop during a not very bright day,voltage drop in the wires, diodes and controllers?
Around how much voltage is lost in each component?

[Sunking]

You're right, im dealing with 12 volts system.Originally my purpose for buying a 12v to 220v inverter was for providing 220vac during camping trips using a car.

Then you have no use for solar unless you like throwing money into a fire pit.

[Mike90250]

The amount of solar panels needed to keep a battery going for a camping trip, is huge. You need to figure out what your loads are, and then we can figure how much solar you need.

There is some loss along each step of the charging path, and it takes higher voltage to charge a battery.