Cost. Useful life. I thought about an off grid system. Batteries are expensive. Also, unless you live in a dry place in the equator, You'll need to account for things like winter, long rainy spells, so either you add more batteries to account for multiple days (weeks? months?) of low generation, or you'll need a diesel/gas generator, or have a hybrid system instead, which basically means you're using the utilities gas generator instead.

Then, subsides are drying up. Systems have a useful life, your panels can be damaged by storms, for maximizing battery life you need to ensure you don't discharge it below 20%, and neither charge it over 100%.

So, in the end, the grid needs to be there anyway, but as most grid costs are fixed, whenever you use it now, it is going to be more expensive.

Generating your own power does not necessarily mean cutting ties with the grid. I think for most people in most places being off-grid would be a real challenge. I’m not sure how Australia does it but in my neck of the woods (northeast US) staying grid-tied is the norm.

I have a relatively big battery (12kWh) which is enough to see me through the evening during the summer months. We do not get quite enough sunshine where I live to be off-grid during the winter, but I can use the battery to hedge against grid outages which are common here in the winter due to storms (eg heavy ice taking down power lines).

The battery in the winter could be used to charge during low cost time periods, assuming your have time of use energy prices. I see people in the UK doing that all the time because the peak prices are very high. I think California is the same.

Batteries have come down a lot in cost, at least the raw ones:

https://youtu.be/3mAx_KE8gz0

Without the tariffs it would be even cheaper I guess.

We do the same in Pennsylvania - I have about 10 kwh of battery. I can't put solar on my roof, so I only have a very small 800w array on top of my garden. I run it as an off grid system that can recharge from shore power, so I have to use all of the energy it produces or it goes to waste. But it saves some money and is enough battery to let me time shift to take advantage of time of use power rates, and it gives me very good run time for refrigerators and internet during outages.

There seem to be a few sweet spots in solar - a tiny array that you use all of without having to grid tie it is really cost effective. (The cost of grid tied solar adds 5-10k to the system cost). Otherwise go big. :)

From what I’ve been reading, sodium ion batteries are about to land later this year and look set to drop costs upwards of 60%.

That and they can be cold booted and stand much more temperature diversity bitter and into frozen temps too.

Just saying, the tech and solar expansion is at run away global growth right now, despite American centric machinations.

There was an article that described that in UK one needs 1 megawhat-hour battery over the winter to be grid independent. Judging by current trends in few years that will be below 40K USD. While this is indeed very expensive in most of US due to much more sun available the required battery would cost below 20k. One can also have a backup generator that can run constantly at maximum efficiency to replenish the battery. Then the whole system can already be below 20K. While expensive, it provides true independence and I suspect grid cost and centralized power is more expensive for society.

These studies tend to always rely on a perfectly balanced grid without any extra capacity to find these massive seasonal differences.

Add a bit of extra capacity to the wind/solar installations and the battery figures usually plummet.

This is for a single home off-grid, meaning solar over-production is already implied. You need enough solar available to charge that 1MW battery in time for it to be useful during those seasonal differences which is going to be multiples of your peak summer generation.

No need to go off grid. You getting solar and battery already positions you to be able to ‘exit the grid’. The experience in Australia has been that the major retailers keep charging infrastructure costs to those who still rely on them. The mass of solar adoption grid and off-grid shifts the playing field.

> their centralised options become redundant

This is not the problem. The problem is that everyone moves to solar for most of the year not using or paying for the infrastructure, then in cold winter nights everyone expects the grid to be able to supply as normal.

Weirdly in the UK it seems to be best to charge battery overnight from the grid and sell back during the day alongside any solar generated.

That appears to be true in places in the US that have time-of-use rates. Sadly where I live, there are no time-of-use rates for residential customers, otherwise I would absolutely do this.

Wouldn’t it be better to fill any shortfall from solar before selling back to the grid?

> I'd expect most tech people will value the distributed nature of solar over equivilents, that by design require centralisation and commerical/state ownership and control.

I do, but I do not find value in rich folks who can afford solar wanting their cake and eating it too.

If you get a solar setup, get batteries. Then disconnect from the grid entirely. You should not be able to use the grid as a free backup energy source for the last 5% of the time you'll need it. Those last digits of reliability are the expensive hard problem to solve. That, or be charged appropriately for adding your potential usage to the capacity market. I understand that this is not legal in many places, and that folks disconnecting from the grid also cause the grid to collapse at some point as well. But at least there would be less of an individual perverse incentive involved.

Home solar folks seem to love their free battery though. Or even worse - getting paid to dump power to the grid when it's value is the smallest. Net metering is not the way to go - home solar should be being paid something around instantaneous wholesale pricing at best, plus fees to manage the more complex management of the grid they cause via being thousands of kilowatt-scale install vs. a single 50MW solar farm.

So far in the US at least, many solar programs have simply been a handout to relatively rich folks subsidized by poorer grid consumers. It's really put a sour taste on something that should be for the greater good. I don't mind that those subsidies were used to jump-start the industry, but that time has long since passed.

tldr; if your total system cost to be fully off-grid and never have to worry about a power outage is not substantially more expensive than being grid-connected, you are likely being highly subsidized by other electricity consumers.

While many rich are benefiting, they are still driving demand, that is funding continuous improvements that funding further efficiencies innovation and driving down the cost per kWh. In a very really way this makes solar cheaper and cheaper, the benefits of this one, unlike the debunked economic namesake do infact trickle down.

I think this was the case when solar panels were much more expensive. But home solar in the US has long ceased to be a useful driver of funding efficiencies and innovation. The cost of panels is now tiny and you are mostly paying for extremely overpriced installation and permitting. The 30% federal subsidy alone is enough to pay for an equivalent amount of utility scale solar outright. Australia has similar labor costs to the US but home solar is 1/3rd the cost to install.