All sources of energy are unreliable to some extent – what matters is modelling that to understand the risk and put appropriate mitigations in place. For source

All sources of energy are unreliable to some extent – what matters is modelling that to understand the risk and put appropriate mitigations in place. For sources which have more inherent variability (such as solar or wind) the mitigation is often storage or over-provisioning. The addition of appropriate mitigations allows us to derive an energy source with the desired level of reliability. The cost of those mitigations (i.e. more storage required with erratic renewables) needs to then be traded off against other energy sources and the associated costs.