rin67630
Solar Enthusiast
I am currently experimenting with powering an unattended off grid networked instrument that continuously draws 500mA (6W) in 50° latitude maritime climate.
The requirements are quite different from providing grid power or even providing off grid home power.
The challenge is to have a panel that is not too large (which would have been difficult to mount on a street lamp pole and would attract vandals) and a battery that does not mind freezing.
The problem is that you get far too much power form the panel in summer and absolutely not enough in winter.
A 100W panel is not sufficient: i will only provide 5W for 6 hours on cloudy days, you need at least 25W for 6 hours to balance the 500mA permanent consumption. More, if the battery needs to catch up a series of cloudy days.
The battery must last for a week or more if fully charged, which happens only rarely in winter.
Of course, two or three hours sunshine are a game changer.
I am just now wondering if having two 100W panels oriented SE and SW will not be better?
On a cloudy day the orientation is almost irrelevant, but if you get two hours sunshine (whenever it comes) having at least one panel oriented well makes a difference, isn't it?
Tracking is not a solution either: too hard to maintain, does not work on cloudy days, the whole thing should be unattended.
What is your opinion?
The requirements are quite different from providing grid power or even providing off grid home power.
The challenge is to have a panel that is not too large (which would have been difficult to mount on a street lamp pole and would attract vandals) and a battery that does not mind freezing.
The problem is that you get far too much power form the panel in summer and absolutely not enough in winter.
A 100W panel is not sufficient: i will only provide 5W for 6 hours on cloudy days, you need at least 25W for 6 hours to balance the 500mA permanent consumption. More, if the battery needs to catch up a series of cloudy days.
The battery must last for a week or more if fully charged, which happens only rarely in winter.
Of course, two or three hours sunshine are a game changer.
I am just now wondering if having two 100W panels oriented SE and SW will not be better?
On a cloudy day the orientation is almost irrelevant, but if you get two hours sunshine (whenever it comes) having at least one panel oriented well makes a difference, isn't it?
Tracking is not a solution either: too hard to maintain, does not work on cloudy days, the whole thing should be unattended.
What is your opinion?
