Advice on deep cycle setup?

pianotuna wrote:
Higher voltage means less line loss (less voltage drop), but to get the full benefit a good MPPT controller must be used.

Charging may start earlier in the day and run later in the evening with MPPT. Losses from heat are slightly worse with MPPT.

PWM may be used with a 24 volt panel but since PWM operates at slightly above the battery volt lots of energy will be dissipated as heat inside the controller. Electronics hate heat. They tend to hate over voltage as well--but some controllers can tolerate that. Personally, over 21 volts I would consider MPPT to be a better choice.

If you want every last erg of power and have deep pockets, then go MPPT.

For a 200 to 400 watt system I would go with the Grape 40 amp controller because it is fully featured, easily available at Home Depot, and inexpensive. With an initial 200 watts it leaves considerable room to add more panels in the future.

I do not know of an MPPT controller that is inexpensive AND fully featured. When panel costs were $5.50 per watt MPPT made a lot of sense even for small systems. But with panel prices under a buck--not so much.

Once 85% state of charge is reached, the acceptance rate of a flooded lead acid battery bank may cause an MPPT controller to operate in PWM mode. That percentage will be higher with high quality AGM--perhaps as high as 95%, but I have not found any documentation for that number.

JohnnyGood wrote:
If anyone has some wisdom on why/how to go with 24 volt panels instead of 12 volt panels, I'd be interested to hear it.

Thanks,

L