Nope no sun, Just indoors in the kitchen counter.
I don't advise using chicken eggs, their whites tastes like plastic when fermented. Only use duck and quail eggs for making salted eggs.
This is the brine method. Inside a container pour brine (I don't do measurements but at least 2 cups of salt ) on the eggs and cover it with a lid. Leave it for 3 weeks to 3 months. It is up to you.
as you see the eggs float so to stop them from floating put some weights like a porcelain saucer to make them sink to the bottom.
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This is the traditional mud method:
Just add some soil in the brine.
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After you are over fermenting them you either have to hard boil the eggs before eating. People use the raw one for making sauces though.
Filipino vendors dye the shells with red food color so they wont confuse them to fresh eggs.
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Filipinos uses the eggs as an ingredient for a Christmas cake known as bibingka
and this 2 ingredient salad with no name:
Just sliced tomatoes and fresh hard boiled salted eggs. You can use it as a cheese replacement for any salad recipe.
It also works well with onions and fiddlehead fern.
In Singapore they use raw salted eggs to make Salted egg shrimp.
In China they use salted egg as ingredient for mooncake desserts.
It makes great toppings for rice or oatmeal porridge.