COMMENT:

Solar power is clearly on people's minds, and my column on the topic generated plenty of feedback.

First, am I paying too much for electricity at 37 c per kWh, and a $2.15 daily charge? A quick look through Consumer's Powerswitch site, and those of other power retailers, suggest I can save $470-$530 a year by ditching Meridian and going elsewhere.

That's a decent saving if so, but goodness me, clicking on the different Low User/Standard Power/Economy-wotsit plans from different power retailers show I could pay 47-51c/kWh if I'm not careful along with high daily fixed charges.

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And there are further complications like paying bills on time "discounts", one-off switching incentives and slightly lower prices if you agree to be locked in over one to two years.

The high pricing and convoluted plans from energy retailers are incentives enough for anyone to look at solar power generation, even without a battery.

Nevertheless, batteries are useful for other times than when the sun doesn't shine. Living in remote areas can mean more frequent power outages as trees pull down lines during storms, for instance.

Lines companies and their frontline workers are mostly amazing at restoring power, but there's only so much they can do.

When the skies go dark and the wind picks up, if the power goes off for an extended period, you could be looking at costly losses as food in the fridge and freezer spoils.

Batteries could help mitigate outages and also smooth out peak loads on the grid.

Auckland's Vector is already trialling network batteries in Glen Innes, and is working to deploy them in Warkworth and Snell's Beach.

"The batteries can help meet the peak demand needs for these growing communities, and can defer expensive and disruptive investment in long-term infrastructure assets, buying time to confirm if they are really needed," a Vector spokesperson told me.

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Saving on building expensive permanent infrastructure is obviously attractive to Vector which is staring at an estimated $5.5 billion hit to complete the remainder of its network.

It's a cost that would be passed on to consumers.

Vector said its network battery installations are portable and can be moved to other locations if needed. Battery-backed microgrids might be a way to manage rising electricity demand and improved network resilience without power prices going through the roof.

The battery portability aspect becomes even more interesting when you throw electric cars into the mix.

They're getting bigger batteries all the time to provide better range. The holy grail is 150 kilowatt hours storage which should give around 800km reach.

We're not there yet, but a Gen 2 Nissan Leaf has a 40 kWh battery, and the new model launched this year fits 60 kWh of energy storage. That's a good amount more than Tesla PowerWall 2 which has 13.5 kWh of capacity each.

Plug a Leaf into your house with Nissan's Vehicle To Home (V2H) system, and you might survive power outages lasting several hours.

Community EV parking garages that double up as charging stations and house batteries, anyone?

Vector's tested V2H since 2017 and last month said it had won co-funding from the Government's low emission vehicles contestable fund to set up a real-world trial at Piha, so we should have some actual data on how well the technology works.

Unfortunately, Nissan is alone in pushing V2H and Leaf is still in "register your interest" mode so the car-as-a-house-battery concept feels a bit like a lukewarm effort overall.

The cars are expensive (40 kWh Gen 2s start at $45,000) which puts them out of reach for most people, even when the dual-use as a house battery is taken into account.

Whether it's per-house, portable network or EV batteries that crack the practicality and affordability barriers remains to be seen.

But it's good there are trials happening because, we're going to need something sooner or later, says I, casting a nervous eye over the Cyclone Oma forecast this week.