<instructions>Your goal is to analyze the following comment and estimate how highly it will be upvoted by the Hacker News community.</instructions><comment><author>ZeroGravitas</author><text>I&amp;#x27;m not a fan of most reporting of these negative price events.&lt;p&gt;First, they rarely explain why the price is negative. As the article explains, solar can switch itself off, so it&amp;#x27;s nothing physical about solar that can cause negative prices, as all solar can switch itself off before it goes negative it would bottom out at zero for those reasons.&lt;p&gt;In most cases I&amp;#x27;ve seen so far, contractual agreements with gas, coal or nuclear (who struggle to switch themselves off quickly without hurting themselves) have been the reasons for negative pricing and the grid wasn&amp;#x27;t actually at 100% renewable at the time of the curtailment. In other words, solar switches itself off, while other, dirtier plants get fined (negative price!) for demanding that they be allowed to still run.&lt;p&gt;In South Australia they&amp;#x27;re doing pretty well on renewable, so it&amp;#x27;s possible they actually are at 100% renewable at these times (would be good for the stories to clarify). If that&amp;#x27;s the case then the negative price is most likely caused by subsidies to wind that are paid per generation. If the subsidies to two renewable plants are different then one will bid the other off the market at that point since the price can go down to the opposite of the subsidy before they make an actual loss.&lt;p&gt;All in all, these negative prices are useful market signals. I wish the weren&amp;#x27;t covered by journalists who seem to think negative numbers are taboo for some reason.&lt;p&gt;The fact that it&amp;#x27;s the same plant that gets switched off repeatedly (rather than all solar reducing output) makes me think this is either a contractual thing that only affects its owner or a regional transmission thing that only affects its geographic location. Again, would be nice for stories to find out which.</text><parent_chain></parent_chain></comment><story><title>Solar farm has to switch off every second day due to negative prices</title><url>https://reneweconomy.com.au/this-solar-farm-has-to-switch-off-every-second-day-due-to-negative-prices-63529/</url></story>
<instructions>Your goal is to analyze the following comment and estimate how highly it will be upvoted by the Hacker News community.</instructions><comment><author>nabla9</author><text>EXPLANATION: Some power sources can’t be shut down and restarted quickly and cost-efficiently. If the cost of stopping and restarting  plant is higher than the cost of selling energy at a negative price for some time, prices go negative.&lt;p&gt;This kind of price fluctuation can increase the overall cost of energy production. We need cost effective power storage solutions and better electric grids to make renewable more effective.&lt;p&gt;&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Duck_curve&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Duck_curve&lt;/a&gt;</text><parent_chain></parent_chain></comment><story><title>Solar farm has to switch off every second day due to negative prices</title><url>https://reneweconomy.com.au/this-solar-farm-has-to-switch-off-every-second-day-due-to-negative-prices-63529/</url></story>