PV panels to an existing diesel generator/battery setup

[onni]

To properly charge batteries you need to have enough amperage from the controller. Too little or too much is not good. The C/10 is the minimum ratio where C = 600Ah.

With a 600AH battery system you will need somewhere around 60 amps which requires 780 watts of panels using a MPPT type charger or 1080 watts of panels using a lower efficient type PWM type charger.

Those are basic math calculations. Depending on where you live and how much good sun you get will allow you to properly size your panel wattage.

Alright, thanks for the clarification. That means I should either aim for at least 800 W of PV panels (and MPPT controller) or reduce the amount of batteries in use.

/Anton

[ILFE]

Now you are figuring it out.

[SunEagle]

Alright, thanks for the clarification. That means I should either aim for at least 800 W of PV panels (and MPPT controller) or reduce the amount of batteries in use.

/Anton

You got it. Be careful with lowering your battery size. Based on your calculated use of 2.5kWh per day on a 12volt system that comes to 208Ah.

Even your 600Ah system is light if you discharge it 33% every day they will not last long. Going smaller will put you in the dark sooner.

[Sunking]

Onni the whole thing has to be designed up front based on your location and daily watt hour usage. Otherwise it will fail period. 99% of mistakes is too small of a system because the the user uses more power than the system can generate. The other 1% over design and spend too much money and possible fry batteries if not matched with panel wattage. When designed properly all the pieces fit and work in harmony. Get one thing wrong and you will have a expensive failure most notable trashing expensive batteries.

Once you learn what it really takes may make you think of something else less expensive.

Based on battery size of 600 AH, I can tell you what the minimum and maximum power wattage the panels have to be. For example a 12 volt FLA battery using MPPT will require a minimum of 700 watts and up to 1100 watts, but I have no idea of what you use in a day or if it will work. On paper a 12 volt 600 AH battery can give you up to 1.5 Kwh per day, and panel wattage of 700 to 1100 can generate that much power if winter isolation is 3 or more hours. If you are using more than 2 Kwh/day on those batteries with 700 watts, your batteries will fail from deficit charging.

Point is you start from Daily use requirements then work backwards. Not just get something and hope it works. Like I said 99% guess wrong, and most of those that guess wrong only have about 10 to 20% of the equipment they need. That means they have not even made a down payment on what they spent so far. Instead of the $1000 they already wasted find out they need another $10,000 they do not have to make it work. Don't be that Knuckle Head.