Bat-droppings(Pipistrelle?),warm roost by river.

Bat-droppings(Pipistrelle?),warm roost by river.

Observation - Bat-droppings(Pipistrelle?),warm roost by river.. Description: Very small droppings in huge numbers; dry and crumbly, about 3 or 4mm in length. Found in lovre ledge of working (thus warm inside) generator building(water driven).In mixed woodland along quiet river banks.3rd photo shows thick layer of droppings at foot

Very small droppings in huge numbers; dry and crumbly, about 3 or 4mm in length. Found in lovre ledge of working (thus warm inside) generator building(water driven).In mixed woodland along quiet river banks.3rd photo shows thick layer of droppings at foot of the wall beneath access louvre.
I have been shown Pipistrelle droppings on window ledges, by a bat expert (with bat-detector).These are certainly similar.