Power quality refers to the stability and performance of the electricity supply compared to technical standards and user requirements. Power quality problems include transient disturbances and longer interruptions that can be caused internally, externally, or by the electricity utility. Examples include transients, short interruptions, surges, sags, and distortions. Power quality incidents can result in costs such as lost data, products out of specification, or destroyed products. Solutions include dual utility supplies, backup generation, uninterruptible power supplies, power conditioners, energy storage, surge protection, installation design, and diagnosis. Power quality issues cost European businesses billions annually.