Feedback on this solar kit?
Hello, I see Harbor Freight has this kit on sale for $140. Yes, I know it's probably the cheapest cheesiest thing I could probably buy because it's from HF, but it's my first endeavor into solar charg...
Forum Discussion
Just to clarify.
75W/17V=4.4A. So 75W panel without MPPT controller is equivalent to 4.4A charger - or whatever the working current of the panel is, equivalent to 5.0-5.5 hours of charging on a sunny day.. This is not a 4.4A charger working 24 hours, and on some days you won't get anything at all.
Battery doesn't need more than 14.8V, so PWM controller will taper those extra few volts off, they are simply lost.
MPPT controller would convert the excessive volts into amps, and you would get 75/14.8 minus 7% controller losses = 14.7A.
The difference between 14.7A and 14.4A is called "MPPT boost" - 6% is not very impressive,so using MPPT controllers with a single small 17V panel (called 12V nominal) is not worth the extra expense of MPPT. Normally, people use MPPT with 30V panels (called 24V nominal), or a few 17V panels in series.
The cost of a fairly good 5A-8A PWM controller like this one is $40-50 and it makes a lot of sense having it with 75-80W panel.
75W/17V=4.4A. So 75W panel without MPPT controller is equivalent to 4.4A charger - or whatever the working current of the panel is, equivalent to 5.0-5.5 hours of charging on a sunny day.. This is not a 4.4A charger working 24 hours, and on some days you won't get anything at all.
Battery doesn't need more than 14.8V, so PWM controller will taper those extra few volts off, they are simply lost.
MPPT controller would convert the excessive volts into amps, and you would get 75/14.8 minus 7% controller losses = 14.7A.
The difference between 14.7A and 14.4A is called "MPPT boost" - 6% is not very impressive,so using MPPT controllers with a single small 17V panel (called 12V nominal) is not worth the extra expense of MPPT. Normally, people use MPPT with 30V panels (called 24V nominal), or a few 17V panels in series.
The cost of a fairly good 5A-8A PWM controller like this one is $40-50 and it makes a lot of sense having it with 75-80W panel.
