Something that works only during certain times of day and weather is not reliable from the perspective of generating electricity.
The fact that your solar installation is in good working condition means it works reliably but that doesn't make it a reliable source of electricity.
Whether or not something is a reliable source of electricity or works reliably are two separate things and OP is talking about the latter. Can I flip a light switch at any time and reasonably expect solar to provide me electricity? No. Then it's not reliable source of electricity.
The fact that your solar installation is in good working condition means it works reliably but that doesn't make it a reliable source of electricity.
Whether or not something is a reliable source of electricity or works reliably are two separate things and OP is talking about the latter. Can I flip a light switch at any time and reasonably expect solar to provide me electricity? No. Then it's not reliable source of electricity.