HI,
I went through all the DC2703A and LT8491, LT8705 datasheets and there are still un-answer questions regarding input and output protections.
For the input, there is a LTC4359 that I really like (it is pricey though!) as an input protection. It protects against revese polarity on the input. It protects the DC supply in case there is a solar panel with higher voltage.
1) However, it does not protects the solar panel and it does not seems to protect agains reverse solar panel polarity.
I am still unsure if the solar panel needs protecting at all. In my application, the DC voltage is 24V, the solar panel will usually output 17V so the solar panel would see higher voltage, but it does not seems to be a problem.
2) But what if I plug the solar panel in reverse polarity... it seems I would need another LTC4359CMS8#PBF for the solar panel? Or maybe a simpler (cost effective) solution for this would be a single FET with resistor like this if the panel can endure the higher voltages.
3) Finally, there is a 3rd problem: the reverse battery protection. I would use a schematic like this on the output, but there might be more to it.
Can't wait to get your opinions on all that. Like they say, we have to use protection! 
