Best electricity plan for solar panels plu sbattery?

[dj4116]

I have 6.6kW PV panels, 5kW inverter and Catch relay to divert excess solar to hot water system, System working well, ten north panels and five west. No shading. I export FIT every day, average over time is more than 10kWh per day.

Some online calculators suggest I would not pay for a battery via grid use saving over 10 years. I have heard that the biggest saving amount comes from installing panels and diverting excess solar to hot water system, which I have done.

However I have also heard that the type of electricity plan in use has a big effect on the economics, eg time of use vs flat rate. I am now on the flat rate AGL Solar Savers (Qld).

Any suggestions about what plan I might adopt to improve the economics of getting a battery? I will consider time of use but not demand charge.

Thanks for any opinions.

[Lester]

DJ, probably fine to just get the battery you want, and wait on your current single rate plan if possible, let things settle in and see what you're using from the grid still.

6.6kw is about the minimum PV that gets installed now, but it seems like you're a light power users and you should be able to manage ok with a battery approx 10kwh capacity or usable.

Going to say 15kwh might give you a lot more flexibility in summer and shoulder months, but winter you might need to top off from the grid in cheaper tariff times (if you do switch to TOU tariff).

There are lots of things to consider . . .

Firstly, what's the avg bill each quarter ?

If only $250 - $300 or other low amount, then it might be a long payback, probably at a guess 10 years.

If it looks viable, next is know your usage for non solar production from your solar app and / or AGL.

See how much you need in winter, summer and the other 2 seasons which should be roughly the same.

Analyse this, or maybe get a battery company to look at it with you and advise.

If you go ahead, after you've settled in, then look at other plans that may give you more benefit, maybe some VPP offers, cheaper or free power for a few hours daily (to charge a battery in winter etc).

Some people now change plans for 2 main seasons, some even change providers and plans for the 2 x 6 monthly blocks of summer and winter weather.

[dj4116]

Thanks for your thoughts on my situation. I am a light electricity user (2 person household). I have comprehensive daily data via my Catch diverter for HWS, and Solar Analytics. I have arranged for two apparently quality installers to visit and give opinions and quotes. I have a Sungrow inverter now, so will probably ask them to quote on 5kW Sungrow hybrid inverter to replace my Sungrow sting inverter. Sungrow has a $1000 tradein program for its inverters. Plus a Sungrow 12.8kWh battery. My research so far suggests the economics of a battery here are marginal at best. Except maybe use of Amber tariff - a high risk strategy. 

[Lester]

Sounds like a good plan, assuming the panels are still producing well.

Not sure how old your string inverter is, your system is reasonably new still ?

The hybrid inverter upgrade is needed for curtailment, if / when FITs start to go negative, as they do with Amber, and might soon with anyone getting the new 'sun tax' solar soak penalty, already in some states.

Eventually I can see most people curtailing between 1000 and around 1500 / 1600, so to get the most from solar a battery is going to be required.

The battery should cover you well from your description, you just need to do the sums to see if worthwhile.

Future proofing a little is a great idea too, with battery rebate savings, this might help cover supply charge increases etc in the coming years.

Quite handy to also charge a battery from the grid in cheaper TOU hours, and use in Peak hours, if you do get onto TOU plan.

Also weigh up the benefits of blackout protection, so checking what's needed with the Sungrow inverter for that (gateway inbuilt or separate?).

Amber is interesting, been following their FB users group for some time, and yes it seems hit an miss from comments.

Comments usually show the posts from people having problems though, so my guess is Smartshift works for the majority.

Problems seem more common for people with smaller pv / and particularly small batteries, more risk of more bill volatility, and also the hardware compatibility to work fully with Amber for curtailment, good Smartshift integration.

Many micro manage, which would be a pain for busy people, but ok for some who see it as a bit of fun like paying stocks, or use Home Assistant  / Raspberry PI to control all their home automation and solar / battery etc.

That take some moderate programming skills I believe.

All the best with your progress and decision, the quotes are a good idea and most will hopefully give good advice that actually is to the benefit of the consumer . . . it's likely good companies will do that.

[dj4116]

Thanks again for your thoughts. The PV/inverter system is 18 months old and is producing well. I had 40kWh of FIT on one very good day. I have an ideal unshaded 25 degree pitch situation, with 10 panels north and 5 west.

The issues of backup, grid to battery, Dynamic Exports (Qld) and possible future FIT export limits are all on my mind. I will raise those with the visiting installers. I hear that Sungrow hardware, being popular, can be setup to cope with these issues.

I input my data into wattever and looked at the with and without 13kWh battery results. The electricity bill saving is about equal to the earning forgone on the $10k for a battery. So from several points of view, the battery looks marginal on a simple $ analysis. Amber or a VPP might make the battery viable. But I do not want a VPP wearing out my battery.

So next step is to hear what installers say.

[Lester]

Sounds like you're right on top of all that matters.

40kwh from 6.6 is great for sure. 

Best export I get in summer perfect curve from my 11.2 is 70kwh, but we have panels east, north, and west, so it's sort of flatter and longer feed in.

I'm participating in the ARENA / SAPN / AGL Solar Grid Savers trail, and from survey questions, I think that soon there will be more FIT options for many retailers being offered, and probable voluntary curtailment during solar soak, with credit offers to participate.

We already know that FITs now are almost worthless in some states / regions, here in SA 2c is the norm, down last year 33.33% 6c to 4c, and down this July another 50% to 2c.

Solar still ok if you self consume a lot, which we do, but pitiful FIT coupled with tariffs going up for peak (53c or so) 13 hours a day, inc 0600-1000 and 1500 to midnight really hurts.

So a battery is on the cards for before next winter.

Maybe consider that FITs might change more in the near future . . .

Some FIT offers are starting to be seen interstate are along the lines of zero FIT during solar soak, and decent FIT in early evening high demand.

That makes sense, retailers pay big $ for power in those high demand times sunrise time and early - mid evening, so offering solar FITs of a more reasonable levels, and saving themselves a huge grid cost, a win win.

Will they do it ?

Possibly reluctantly and begrudgingly, but I can see them coming around.

Otherwise the likes of Amber is going to take an ever increasing number of these new battery recipients, leaving retailers to pay those huge demand period costs, and losing profits.

[dj4116]

FITs are decreasing in Qld also. From 1 Jul I am getting 10c/kWh for first 10kWh and 3c for the rest (down from 5c). But many/most other plans are less generous. So the FIT situation for the future is a good if uncertain point.

There is a very active UK based youtuber called GaryDoesSolar who produces a lot of good work. Apparently in the UK FITs are increasing. I do not know why. But the current trend here is certainly down. Perhaps the idea is to encourage battery uptake, to encourage more self consumption. And rescue the authorities from the impending dark age, due to unreliable grid supply.

I await the installers' ideas and quotes with interest.

[Lester]

UK might be so starved for power it has to give people a decent amount, maybe retailers have have put in more intensive large battery storage to enable the power shifting to peak needs ?

I think we'll see those better FITs coming through for people with batteries in the coming year, so those invested in batteries can make 12c or whatever in evening peaks, for maybe 3 - 4 hours.

The massive uptake in batteries happening now must send a signal to retailers they have a great win win possible now to get very cheap feed in when they have massive peak use mwh costs.

I think that's what's really hurting retailer profits right now, and that gamble they have to take on peak pricing / costs are inflating bills for all (their hedging of charges to consumers), hurting in particular those without solar.