Home solar/batteries revisited in 2019

[Halcyon]

Just over two years ago I looked into battery storage for my home. At the time, over the 10 year life of a good quality system, I calculated that it would be double the cost of simply buying energy from the grid.

Having just received a AUD$1000 power bill for the last quarter, it has prompted me to look into the cost and economics of battery storage again. It's currently winter in Australia and all the heating in my home comes from a 3-phase ducted air conditioning system. I also have a server rack running 24/7 so these two items are by far the biggest consumers. During the winter and summer months, I'm consuming between 35-45 kWh/day on average, dropping to about 20 kWh/day during autumn and spring.

I currently have a 5 kilowatt solar array on the roof, which doesn't help in the evenings when everyone is home. According to the last bill, in the last 90 days I generated an excess of 459 kWh (a little over 5 kWh/day) which was fed back into the grid. I would rather put that unused energy to use in my own home, rather than getting a measly 12.5c/kWh back from the energy company.

I'm looking at the products available from my energy provider (yet to receive a formal quote). In terms of solar, they supply Trina or Q Cell branded panels with Zever, SMA or Enphase inverters. For their battery systems, it's either Tesla or Redback inverter with Pylontech batteries. Does anyone have any experience or thoughts with these products? Currently I'm using LG panels connected to a Bosch inverter.

[tautech]

To make the most of it with your power consumption IMO you need a larger PV array.

My son in Perth has just days ago upgraded his system to 21 panels in a split North/West configuration for a total 6.5KW and a 5KW German inverter back into the grid. Overcast days still produce 20+ KWh into the grid.

[Halcyon]

To make the most of it with your power consumption IMO you need a larger PV array.

My son in Perth has just days ago upgraded his system to 21 panels in a split North/West configuration for a total 6.5KW and a 5KW German inverter back into the grid. Overcast days still produce 20+ KWh into the grid.

100% agree. Part of my plans are to double the size of the array and maybe add batteries. Currently all my panels are facing north but I have terrain to the west and bush to the east which shields some of the light when the sun is low in the sky. I have a significant amount of roof area facing east which would catch a lot of the morning/midday sun and potential space to add a few more panels on the north facing side.

The other issue I have is that the current inverter is only connected to one of the phases, which I assume means that the air conditioning is drawing power from the grid on the other two. It's a huge system and unfortunately not an "inverter" type (there is a huge thud when the contactors close and the compressor starts up).

[digsys]

One of the groups I've been part of for many years is - https://renew.org.au/   (originally ATA - Alternate Technology Association)
It is a huge group, with work groups all over the world, mainly solar power installations. There is a LOT of information at that site, including dozens of past publications - renew and sanctuary. Many of our members do solar installations of every sort, and are honest to deal with. Members will also help with any questions people have. If there is an issue of the publications that you can't access, I can pass it on to you. It is worth at least having a "flick through" all of the links / info on that site.
Two things I will say, don't bother with expensive / over-priced batteries. Many members pick up 2nds or "cheaper" types for $1-2K or up to $5K for really big storage. They can last easily 5 yrs+ if treated properly. Others have been buying 2nd hand Tesla car packs and using them - but there is a huge demand for that route :-)
2nd - A very efficient method of use (battery packs) is to only use them during peak charge time - select a plan that is extreme between peak / off peak. That way you can end up with a much smaller pack. Also, count on 1-2 days redundancy, for a bad cloud period.
If you have any specific questions, feel free to ask.

[tautech]

To make the most of it with your power consumption IMO you need a larger PV array.

My son in Perth has just days ago upgraded his system to 21 panels in a split North/West configuration for a total 6.5KW and a 5KW German inverter back into the grid. Overcast days still produce 20+ KWh into the grid.

Been running for just over a week now and I got this phone screenshot of the last few days performance.

[NiHaoMike]

Look into thermal storage, way cheaper than batteries and very long lifetime.

[bdunham7]

If you are heating with your aircon (we call that a heat pump) then you actually use a lot of power at night, so storing your daytime production for use then seems tempting.  I think it is still a bit beyond economic reach though--perhaps you can post some actual numbers when you get quotes?  How cold does it get there and what are your electric rates (and feed-in tariff, if separate)?

If you have three-phase, I'd consider using the Enphase system and perhaps even converting your existing arrays.  You can have multiple arrays and as long as they are in groups of 3 (or close to it for larger arrays) they'll feed into your three phase system evenly and efficiently.  Actually, I'm surprised you can get a system approved the way  you have it--is your three phase on a separate service and meter from the single-phase?

[nctnico]

If you are heating with your aircon (we call that a heat pump) then you actually use a lot of power at night, so storing your daytime production for use then seems tempting.  I think it is still a bit beyond economic reach though--perhaps you can post some actual numbers when you get quotes?  How cold does it get there and what are your electric rates (and feed-in tariff, if separate)?

I vaguely recall reading an article saying that it makes more sense to store heat as heat in the ground compared to feeding electricity back & from the grid. During winter you typically have much less solar power input so if you have a system which offers storage which can effectively bridge several months then it will solve a lot of problems. Batteries are nice for day to day fluctuations but they don't solve seasonal energy requirements.

[NiHaoMike]

Probably would be cheaper to make storage tanks (using water as the storage medium) than installing geothermal loops. That said, DIY geothermal is very well possible.
https://ecorenovator.org/forum/showthread.php?t=484

[nctnico]

Probably would be cheaper to make storage tanks (using water as the storage medium) than installing geothermal loops. That said, DIY geothermal is very well possible.
https://ecorenovator.org/forum/showthread.php?t=484

Be aware that you'll probably need permits to drill holes in the ground. One of the dangers is that you penetrate layers of ground water which then leak into other layers of ground water used for drinking water and potentially contaminating your area's drinking water supply. Needless to say it will cost you dearly.

[Ice-Tea]

Waiting for the delivery of a Solax Hybrid inverter and Battery pack. Not having installed it yet, can't really help you much.

Another idea, as you seem to use a lot in your AC: set your AC a few degrees colder during the day, turn it up (or off) at night.Uses your house a s thermal battery (as others have suggested )