No, electricity is not likely to become a deflationary product. It hasn't been in my lifetime and I don't see that changing. Products which do that are weird and they don't tend to do it for very long.
There was a period (last century, more than fifty years ago) when Oil was deflationary in the US, as the very easily extracted Saudi Oil came online and US import bans ended - you'd pay the same dollar price to fill a car with gasoline in one year as the next and of course wages continued to grow so that oil is getting cheaper in real terms. But that's a long time ago, a time when gasoline was 30 cents per gallon.
Solar PV is just straight up cheaper than any fossil power. Solar Farms the UK agreed to subsidise in 2022 came online early last year and even in those more normal times (before Trump started a war in the Middle East) the "subsidy" amounts they were paying us totalled a few million quid a year because the fossil power was so expensive. Once Trump got into it, we were being paid like £3-4M per month in "subsidy" because of course the fossil fuel costs more now but sunlight is still free.
But that does not translate into lower prices for consumers, at most it means their prices might not rise as quickly.