Solar and batteries are already cost competitive with gas when it comes to adding new, 24 hour, firm generation. Mileage does vary by location, but many cities (globally) could get to 60-99% powered by solar + battery while being just cheaper than a new gas power plant. This is using numbers from 2024, and both of these technologies are in a cost free fall* and have been for a long time.
*tariffs not included, but they are arbitrary BS
@Dippy If you examine the California dataset closely you will see battery charging happening at night sometimes. At those times they are using batteries to hedge on electricity prices not to store any surplus solar power.