New house build with 6.6kw EnergyBuild Smart Solar - how much to add a battery?

[morh]

As per title, I have a new build that was optioned with this solar system:

EnergyBuild Smart Solar package including 6.6kW (nom.) PV solar electricity system with 5kW single phase SolaX inverter, In-wall inverter enclosure, Tier 1 Jinko solar panels, 10 year warranty on solar components, Level 2 7.2kW max. electric vehicle (EV) charger and Smart Energy App.

I was wondering if anyone has quoted on how much to add a battery. I've found the Solax TRIPLE POWER 5.8kWh HV LFP Solar Battery – T58 MASTER for 4.5k, but not sure if my inverter would be compatible with that. And even if it is, would I still need any other component? If not, the installation costs shouldn't be too much as I have the inverter already, right? Nah?

Also wondering if adding a battery makes any financial sense. Thanks

 

[somethingon]

@morh Re financial sense try this site

https://www.solarquotes.com.au/

 

[theyearofthelady]

@morh I am in process of having battery installed (actually have one in and waiting on second)

In general terms it seems that roughly $1 per watt hour (or $1,000 per kwh) of storage is the sort of typical cost, which your Solax quote is in that rough ballpark, and makes it look quite competitive actually.

I don't know the specifics of your setup so not gonna reply on that question, I had an existing setup and my inverter is not battery capable (not a hybrid inverter) and I wanted some coverage in a blackout scenario (I am in regional VIC and have experienced blackouts due to storms) so rather than replacing the inverter I looked at AC coupled batteries that can keep at least the basics (fridge etc) going, and also keep the solar panels working in a blackout which is big for us. The most obvious one is the Tesla powerwall 2 but that is on the pricy side, I ended up going for a FranklinWH battery system which is relatively new to the market and not well known (a risk for sure) so far it's been good and looking forward to the 2nd battery.

From a straight financial sense, batteries still don't stack up sadly. With the small FIT now, financials work best when you can avoid drawing from the grid and use your battery in peak periods, and charge the battery via solar and the grid in offpeak, obviously if you can charge the battery fully from solar each day and never use the grid that is the best, but in winter that is pretty unrealistic unless you have a huge solar system. We were prepared to pay more to cover blackouts so there was more than a strict financials at stake for us.

Have a look at your usage pattern during a day. Your peak is probably 3-9pm (check yours) and see if you can identify what your typical usage is in that period.. in simplest terms you could look at your bill and see how much peak you used in total and divide that by the number of days in the billing period. if you can get a battery big enough to cover that daily peak usage (plus a bit extra if you averaged) then it is going to be not too bad.

A 5.8kwh battery is also not a lot of storage realistically, maybe for you its big enough to get through the peak which would be ok. Its something battery sellers don't like to be up front about I have noticed, I found an installer that was a bit more upfront and he admitted a lot of his work is actually fitting extra batteries to existing, people get a small battery to start with and realise it isn't really big enough and buy more...

 

[morh]

@theyearofthelady Thanks for the reply mate. I have a similar goal, living in semi-rural QLD I also want to be prepared for blackouts which are not rare around here. With my new build getting solar I was wondering if adding a small battery was a better idea than getting a 2500W petrol generator + switchboard (about 1.8k installed). Everywhere I look says about 10k installed for a 5-6kw battery... which sounds a lot considering what I have and how much that Solax costs by itself... but perhaps my inverter isn't hybrid like you said and more gear is required...

Our energy usage is low (300$ per quarter), so that size of battery would likely be enough between 5-11PM with some planning... which would help pay for it, but the main goal again was in case of a blackout.

I guess I will have to wait and see, grab the inverter model after it's installed and check online if it's compatible with a battery, then get some quotes.

 

[theyearofthelady]

@morh yer we are heavy users, no gas or water supply, so all cooking & heating and basically everything is done via electric (aside from wood heater we fire up on the really cold days) even water requires power for the pump to run. You know when you are in an extended blackout when you can't flush the toilets or wash your hands without carrying buckets lol

a typical usage for use is around 28-35kwhrs each day, and I should have written it down but I think I worked out we used around 12-15kwhr in the peak periods, sometimes more (it's hard to avoid using things like the oven in peak periods).

Part of the reason I chose the franklinwh batteries.. is you can also hook up a generator to it. We can charge the batteries via a portable generator for example in a blackout and low sun days, which should mean we can go then overnight on the battery ok.

 

[mike84761]

@theyearofthelady The only way to make a battery worthwhile at the moment, assuming you are motivated - is to join amber electric and expose yourself to wholesale pricing.

For example you would maximise daytime usage during solar excess and fill battery from the grid where possible during periods of negative FiT (when other people are exporting too much, you get paid to fill your battery).

You just discharge your battery during the periods of high demand (for example, 5-8 on a hot or cold afternoon means a lot of cooling or heating, so wholesale FiT skyrockets. Putting aside for example the really high spikes e.g. $15/kw FiT, you can be exporting 80% of your battery during peak demand for 60c/kwh FiT (I see regular days so far where I make $100 for one discharge, biggest was $360). You have to fine tune it if you use smartshift to automate it. You'll have to consider all your energy use at night and consider conserving power during peak demand so you can sell your stored power for profit. It's not really profit but it's your ROI. The more you can make your battery generate a return for you, the better.

The powerwall and sungrow batteries are both designed for full discharge once a day for 10 years essentially. Most of the time you won't be discharging more than one full cycle per day anyway so wear and tear on the battery is going to be about the same as normal use. Plus with the powerwall 2, they degrade with time anyway so ultimately you want to get your ROI asap so you can either upgrade or add additional batteries / panels to expand on your sustainability.

My ROI is about 5.5 years based on my returns so far. That's for a tesla powerwall 2 and my solar system. I'm considering another powerwall in November when the nsw subsidies kick in.

Prior electricity bill was $2000+ per year.