My friend Ken Mardle (not a PICList member) makes the following good points=
..


A decent MPPT unit probably needs to be electrically "quieter" than
many other SMPS units around the home because it will often have a
long "aerial" on its input or output or both (depending on where it is
sited relative to the PV panels and batteries).

For a buck converter the input is generally noiser than the output  -
so there is greater potential for radiated noise if the MPPT unit is
located remotely from the panels.  In that case a properly designed
EMI filter located at the input to the MPPT should help mitigate any
problems.

The output can also be noisy though  - especially if the flywheel
diode is poorly chosen (and the problem can be made much worse by poor
PCB layout).  Again, a properly designed EMI filter should help
mitigate the problem.

Problems can also occur with inadvertent ground loops  - such as can
occur if the panels are say grounded to a roof structure and the
output of the MMPT is grounded to some other point.  Ideally there
should only be a single ground point in the system.


 Russell
--=20
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