Thread: Big storm and no power in SA

For those of us on the original good feed in tariffs, it is better to feed into the grid during the day and use the power companies cheaper electricity at night.

Originally Posted by DiscoMick

Smart inverters are already making a big difference to maximising the potential of battery storage. Premises can meet their own needs, export the surplus and, if the grid fails, draw down their own batteries to keep operating. What's not to like about that? You'd be negligent not to take advantage of this opportunity.

currently inverters are tripping when there is a disturbance. sometimes this adds loads to the grid making things worse.

Originally Posted by vnx205

Is it true that with the changes in what you are paid for electricity you feed back into the grid from your solar panels, you are better off running appliances during the day so that you are using your own free electricity instead of having to buy it at night?

thats what I do. i'm only getting 6cents FIT now, so it's more worthwhile for me to use it.

Originally Posted by Homestar

This is also why battery banks make so much sense now - you can store what you make during the day to offset having to buy too much at night.

depends. yesterday my solar made 16MWh but my load was 35MWh. yesterday i would consider to be a typical winters day.
batteries are no good to me unless i double the size of my solar system, which would cost money.

Originally Posted by Eevo

depends. yesterday my solar made 16MWh but my load was 35MWh. yesterday i would consider to be a typical winters day.
batteries are no good to me unless i double the size of my solar system, which would cost money.

In Vic., for the average winters day you would have about three hours of energy production. Worst case, I would estimate the possibility of three days straight of no energy production. My home uses about 15kWh each day (more on weekends). So, that is around 45kWh useable of battery units (probably around $60,000 worth) and around 10kW of solar panels (probably around $10,000 worth). That would be around 35 years of power bills. Bear in mind the batteries will only last around seven years and the solar panels twenty years so that's about $260,000 (and I haven't included the cost of maintenance) for off grid power compared to $70,000 (35 years) thermal grid power.

That is ball park figures. Post up your own. if you disagree.

Originally Posted by Mick_Marsh

In Vic., for the average winters day you would have about three hours of energy production. Worst case, I would estimate the possibility of three days straight of no energy production. My home uses about 15kWh each day (more on weekends). So, that is around 45kWh useable of battery units (probably around $60,000 worth) and around 10kW of solar panels (probably around $10,000 worth). That would be around 35 years of power bills. Bear in mind the batteries will only last around seven years and the solar panels twenty years so that's about $260,000 (and I haven't included the cost of maintenance) for off grid power compared to $70,000 (35 years) thermal grid power.

That is ball park figures. Post up your own. if you disagree.

i agree. i would need 10-15KW of solar and 30KWh of batteries


my biggest load is heating.
when i dont use the AC, i'm looking at 5-10 KWh per day.


you can see my solar production and house load here for anyone interested.
Eevo Home 4.995kW | Live Output

Currently the cost of batteries is too high to economically cover every normal period of consumption, so making up a cost based on being off grid is a little strange. Daily cycling of one battery will give a higher return on investment than occasional draining a multiple bank. Despite all that, batteries are already well below the cost estimated by Mr Marsh and have 10 year warranties to boot. Two 14kWh PW2's fully installed come in at around $18K and $60K would give you 98kWh of batteries, fully installed. Derate them for age at whatever rate makes you feel better. Lithium batteries charged and discharged at relatively low rates will last much longer than at high current rates. Tesla car batteries that have been frequently fast charged are showing bigger capacity loss than the same ones only home charged in 5kW or less chargers. PW2s seem to be rated at around 0.4C at the highest to achieve long lives.

Powerwall | The Tesla Home Battery

And battery prices are expected to continue dropping as economies of scale kick in. No-one would buy a 100% system right now based on price alone but in 5 years time it is likely to be much more attractive.

Originally Posted by bee utey

in 5 years time it is likely to be much more attractive.

as well as solar coming down, i look forward to it.

the labor will be the biggest cost as usual.