Recently there is a wave of ads/posts on my facebook about solar energy, ranging from installations to solar tax.
I did a quick calculation from https://www.energywise.govt.nz/tools/solar-calculator/, using all the standard attributes and costs, it worked out that I will save a HUGE(not) $1100 in 22 years, that is without any issues within 22 years. I don't really think it's worth installing right now, but if you are so concerned about the environment, it doesn't hurt to go ahead I guess.
So what is the bottleneck for us to save money from? The solar panels seems they are reasonably efficient, so that shouldn't be the problem. If it's not the panels then must be the batteries! After some research on the batteries offered with the solar package, they don't store enough energy to last the whole night, especially if you rely electricity for heating. Based on the following battery specs, the biggest one is 9kwh, if you use heatpump + fridge + hot shower + watch some TV + do some cooking, the battery will prob only last 3-4 hours.
I guess right now it's not the best time (cost effective) to install solar panels, until there is a breakthrough/revolution on battery technology.