Thor Forums

[Long & Winding road]

Originally Posted by scrubjaysnest

A few things to keep in mind. A 220aH battery back discharged to 50% requires 22 amps for proper recharge; that's about 500 watts of solar.
If you don't go below say 75 to 80% discharge the 5% minimum rate of charge will get you by ok.


MPPT controllers are expensive and produce no real value for solar panel arrays below 400 watts as a minimum. They will give you a little savings in wire cost.
Check out the solar blog at Freecampsites.net
Also check out "the 20 golden rules of solar"

I think you misunderstood the "22 amps / 500 watts of solar" thing. It might need 22 amps of total input but not at one time (I have not check your facts). If its its true it would be more like 10 amps x 5 hours is 50 amps per a day (thats 200 watts at 5 amps each x 5 hours) over a normal sunny day. SO really only 2 or 3 hours should come close to filling the batteries?

Im just learning about solar stuff so I dont pretend to have the answers. But almost every website I visited as a general rule says "100 watts per 100 amp hours of battery". So 200 amp hours = 200 watts of solar.

Plenty of RVers are using only 200 watts / 200 amh and going down to 50% discharge and not having prolems with full sun. It internet if full of these blogs.

I would not waste my time with solar if I was only using 25 % or less of my power in 24 hours.

MPPT are not that expensive IMO. Plus I think they are worth it in the long run. Sure I could get by with PWM but I was going to purchase a MPPT thats large enough for 400 watts of solar that way I can add two more batteries down the road and use the same solar controler.

Plus I hate how inefficent the PWM's are... this would drive me crazy .... I would be thinking how much better it would be if I just spent a little more. Im the type person that will be looking at the data 10x a day (input, output, amps, watts, volts etc) analyzing it for my own entertainment and in preparation for my "Retirement RV" and also for my home 10 years from now.

But thanks for the input.

The only part of the equation that Im struggling with is "Flexible or Ridgid" Each has there pro's and con's. I was leaning towards Ridgid but I like some of the Flexalbe advantages. Now my head is spinning.