Charge On Solar Australia

[bradtem]

Do you have net metering? If so, there is not much merit it working too hard on making sure your car only charges when the solar panels have a surplus. In the future, there might be, when we get to having so much solar on the grid that the grid refuses to take more, but that's not now.

If you don't have net metering, then this can be a financial win, though there's no emissions difference. If you are grid tied, your solar panels are just part of the grid's generation ability, and your car part of its load. There's a very minor increase in efficiency if you time it in this way.

The bad news is this. No matter how much solar you have, every mile you drive in your car causes the grid to burn more dirty fuel. Even if you generate 10x as much power from your panels, when you charge your car you send less power to the grid, and so the grid now needs to burn more fossil. Drive your car less, and your panels send more power to the grid, and it burns less fossil. Almost exactly the same as if you had no panels at all!

The best you can do (and I do it) is contract so that your money for grid electricity only comes from renewable providers. I do that, not all places allow it. In that case, the money you send to the grid will encourage the addition of renewable sources more.

This is just the hard math. Putting in panels is good, and improves the grid. The pairing with your car is unrelated. If you don't have net metering, there's a big financial gain to using your own generated energy though.

 

[EcoCloudIT]

I

A slight change to EcoCloudIT's advice (and thanks) if you have a Powerwall:

Have the latest Tesla app on phone (my iPhone has 4.30.5).
Logout and log back in.
New feature will now be there.
The app will subsequently pair the phone to your Powerwall (this is the only deviation - it was automatic for me).

Also worthy of note is that you can't add a Tesla wall charger to the app unless it's the Gen 3 (Gen 1 and 2 not supported)

Interesting, I am on Gen 2 wall chargers (2x of them)…..all working for me it would seem…

 

[EcoCloudIT]

[Edit]
The Home screen displays the wall charger regardless of generation, so unclear why you need to add it manually.

It appears that you can't give battery charging priority. By default, the Gateway (or app?) seems to give excess solar (what the house doesn't need) to charge the car, then the battery will be charged, and then the excess will go to the grid. I'd rather have the battery charged first, then the car, and then out to the grid. ChargeHQ can do that. Have I missed something?

You are correct and I am seeing that this morning.

ChargeHQ is definitely more feature rich. I wish they had a 2x car solution that doesn’t cost $14 per month (what one needs to pay to have it work now with 2x EVs)…at the moment I’ll use my 3 off of Tesla Charge from Solar and ChargeHQ for the Model X.

 

[EcoCloudIT]

Do you have net metering? If so, there is not much merit it working too hard on making sure your car only charges when the solar panels have a surplus. In the future, there might be, when we get to having so much solar on the grid that the grid refuses to take more, but that's not now.

If you don't have net metering, then this can be a financial win, though there's no emissions difference. If you are grid tied, your solar panels are just part of the grid's generation ability, and your car part of its load. There's a very minor increase in efficiency if you time it in this way.

The bad news is this. No matter how much solar you have, every mile you drive in your car causes the grid to burn more dirty fuel. Even if you generate 10x as much power from your panels, when you charge your car you send less power to the grid, and so the grid now needs to burn more fossil. Drive your car less, and your panels send more power to the grid, and it burns less fossil. Almost exactly the same as if you had no panels at all!

The best you can do (and I do it) is contract so that your money for grid electricity only comes from renewable providers. I do that, not all places allow it. In that case, the money you send to the grid will encourage the addition of renewable sources more.

This is just the hard math. Putting in panels is good, and improves the grid. The pairing with your car is unrelated. If you don't have net metering, there's a big financial gain to using your own generated energy though.

I just look at it from a personal viewpoint.

I’ve not paid for electricity, or grid supply charge, in nearly 5 years (since the PW2 was installed).

Even with the 2x EVs charged up and household (with zoned air-con) I produce and dump in to the grid, around 5 months of the year, enough to offset any draw and supply charge for the other 7 months of the year.

 

[paulp]

That's fair. I wasn't sure whether using the wall charger would make a difference, but I guess not.
That's a shame, it would have been cool to have a charging station that only offered green energy for any EV the charge, without needing to pay for a more expensive setup. Oh well, at least my Tesla can be solar-only from now on.

The Teison solar charger can do that, and lets you reduce the amps so that you can get more solar use. It is only a few hundred more than a tesla wall charger. The zappi can also do it but is a lot more expensive.

 

[Vostok]

It appears that you can't give battery charging priority. By default, the Gateway (or app?) seems to give excess solar (what the house doesn't need) to charge the car, then the battery will be charged, and then the excess will go to the grid. I'd rather have the battery charged first, then the car, and then out to the grid.

I agree that’s dumb. Car should definitely be lowest in the hierarchy. I was just about to dump my home-brewed smart charging script to use the native Tesla solution, but not if it prioritises car charging above PW2 charging.

The default should be PW2 charges first. Else, there should be a user-toggle to select which load you want to have as priority.

Hopefully a future update will fix this.

 

[Vostok]

@meloccom - we have a bifurcated discussion on this topic in 2 threads now - here and in Tesla Software Updates. There’s a valid case for this discussion to be in one or other thread, but it’s not great to have it in both, stuff is repeated or missed.

Given Charge on Solar is a specific new feature of the Tesla App and not a more generic software update, I suggest all the posts on this topic be moved here, and the thread title be changed to “Charge on Solar - Australia” since that is the specific name of the feature.

Just a suggestion, others may disagree

 

[meloccom]

Like Vostoks post if you agree.
If there are a lot of likes I will move the posts.
However you should be aware it will sometimes make the threads hard to follow as posts are inserted chronologically.

 

[tyrotex]

A slight change to EcoCloudIT's advice (and thanks) if you have a Powerwall:

Have the latest Tesla app on phone (my iPhone has 4.30.5).
Logout and log back in.
New feature will now be there.

I had to log out of the app, then completely restart my iPhone before the CoS option appeared.
I had previously done the logout, then login dance, with no effect.

The app will subsequently pair the phone to your Powerwall (this is the only deviation - it was automatic for me).

My phone was already paired to my PW, but the process seemed to either do it again or it accepted the existing pairing.

 

[paulp]

[Edit]
The Home screen displays the wall charger regardless of generation, so unclear why you need to add it manually.

It appears that you can't give battery charging priority. By default, the Gateway (or app?) seems to give excess solar (what the house doesn't need) to charge the car, then the battery will be charged, and then the excess will go to the grid. I'd rather have the battery charged first, then the car, and then out to the grid. ChargeHQ can do that. Have I missed something?

Tesla have that wrong. The battery generally has to be charged daily, the car is a larger capacity and can wait. Some people (suggest they are a minority) may use their full range daily so the choice would make sense for them

 

[Vostok]

The bad news is this. No matter how much solar you have, every mile you drive in your car causes the grid to burn more dirty fuel. Even if you generate 10x as much power from your panels, when you charge your car you send less power to the grid, and so the grid now needs to burn more fossil. Drive your car less, and your panels send more power to the grid, and it burns less fossil. Almost exactly the same as if you had no panels at all!

I don’t think that is quite right. Every state in Australia except TAS has relatively high and growing VRE (variable renewable energy). VRE is frequently curtailed because lumbering fossil plants cannot respond quickly to demand changes and so VRE is the sacrificial lamb if the power can’t be sent anywhere.

Exporting less to the grid will mean less VRE curtailment, and so the renewable power you don’t export is replaced by grid renewable power that is not curtailed. Therefore the percentage of renewable energy in the grid will remain unchanged whether you export or not.

 

[moa999]

Video from Lee on setup and it working

 

[EcoCloudIT]

I agree that’s dumb. Car should definitely be lowest in the hierarchy. I was just about to dump my home-brewed smart charging script to use the native Tesla solution, but not if it prioritises car charging above PW2 charging.

The default should be PW2 charges first. Else, there should be a user-toggle to select which load you want to have as priority.

Hopefully a future update will fix this.

Actually, with ChargeHQ you can priorities your battery or car....I believe you can even say things like when the car gets to 50% put the rest in to the home battery....when it is full continue on the car...etc.

 

[noddy@teamterm]

The log out & back in worked for me. Interestingly it is working currently with my UMC as we gave our wall charger away to a friend who has 3 phase. The UMC is plugged into a 5 pin 32a plug.

As we no longer have the wall charger, on the display it shows as offline. Power going to the UMC is shown as going to home. On the car display it is showing as charging, and the rate is varying (currently 24a) as expected and nothing is being pulled from the batteries.

It is a shame we can't prioritise the charging house batteries first, but I assume that will become available sometime down the track. In the meantime I will probably stay with ChargeHq for now. Still it is a welcome new feature.

 

[jamesgo]

TBH I mainly charge these days when the wholesale price goes negative (it's nice to get paid to charge the car), that said I enabled charge on solar yesterday.

 

[cafz]

Do you have net metering? If so, there is not much merit it working too hard on making sure your car only charges when the solar panels have a surplus. In the future, there might be, when we get to having so much solar on the grid that the grid refuses to take more, but that's not now.

If you don't have net metering, then this can be a financial win, though there's no emissions difference. If you are grid tied, your solar panels are just part of the grid's generation ability, and your car part of its load. There's a very minor increase in efficiency if you time it in this way.

The bad news is this. No matter how much solar you have, every mile you drive in your car causes the grid to burn more dirty fuel. Even if you generate 10x as much power from your panels, when you charge your car you send less power to the grid, and so the grid now needs to burn more fossil. Drive your car less, and your panels send more power to the grid, and it burns less fossil. Almost exactly the same as if you had no panels at all!

Note this thread is in the Australia forum.

Here net metering is done based on net instantaneous power flow. So your instantaneous production is netted against your instantaneous consumption, and the resulting net power flow either accumulates grid import energy or grid export energy depending on overall flow direction. You then pay grid import charges on the net imported energy and get paid solar feed-in tariff on the net exported energy.

The grid import charges tend to be significantly higher than the feed-in tariffs (the former in the 20-30c / kWh range, the latter more like 5-10 c/kWh). So this means it's always a financial win to load-shift your consumption to times when it can self-consume your generation.

Rooftop solar has also seen such take-up here that export limits have been common for a few years now - 5kW per phase being typical, so if you have a 10kW inverter with a 5kW export limit then at some times of day there might be 5kW of load you can add that won't alter your exports to the grid at all. There's also the factor @Vostok mentioned that there's frequently lots of grid-scale renewable generation that gets economically constrained, but that's hard to reason about because a lot of that generation also gets constrained by limitations in the transmission network too.

 

[bradtem]

Note this thread is in the Australia forum.

Here net metering is done based on net instantaneous power flow. So your instantaneous production is netted against your instantaneous consumption, and the resulting net power flow either accumulates grid import energy or grid export energy depending on overall flow direction. You then pay grid import charges on the net imported energy and get paid solar feed-in tariff on the net exported energy.

The grid import charges tend to be significantly higher than the feed-in tariffs (the former in the 20-30c / kWh range, the latter more like 5-10 c/kWh). So this means it's always a financial win to load-shift your consumption to times when it can self-consume your generation.

Rooftop solar has also seen such take-up here that export limits have been common for a few years now - 5kW per phase being typical, so if you have a 10kW inverter with a 5kW export limit then at some times of day there might be 5kW of load you can add that won't alter your exports to the grid at all. There's also the factor @Vostok mentioned that there's frequently lots of grid-scale renewable generation that gets economically constrained, but that's hard to reason about because a lot of that generation also gets constrained by limitations in the transmission network too.

My apologies for not properly considering the Australian context. The net metering which is common in many parts of the world pays the same rate in and out, and as such there is no financial reason to attempt to direct your loads to when you are generating. In the case you describe above, with a high price from the grid and a low price out, there is a strong financial incentive.

Whether there is a green incentive is more complex. If they will shut off other solar farms because you are putting more power onto the grid from your home, then there is a green benefit to you balancing your loads and generation. That will become a bigger problem, as I pointed out, when the mid-day solar surplus increases. It is actually forecast by some that prices for power at noon will go negative, though that's a problem that should fix itself as both storage facilities, and cars, all work to try to charge themselves on negative-price power. This is why most charging stalls should be at offices eventually, you want them in places cars are plugged in mid-day. Today, most stalls are at homes, because night is the most convenient (and currently cheapest) time to charge. Of course if your car stays home in the day, the home charging station is a great place to get that negative price power, if they offer it to residential customers.

The solar power of course is not negative priced, but if there's a glut of solar sold on a low price contract, the power sources that can't easily turn off (nuke, combined cycle, wind) will go to negative prices. Solar, hydro and peaker natural gas are so easy to turn off they can go cheap but don't need to go negative.

 

[Vostok]

That will become a bigger problem, as I pointed out, when the mid-day solar surplus increases. It is actually forecast by some that prices for power at noon will go negative, though that's a problem that should fix itself as both storage facilities, and cars, all work to try to charge themselves on negative-price power.

That already happens here frequently, at least at a wholesale level, particularly in South Australia which in 2023 achieved 71% renewable power purely on solar and wind.

During the day, there is often a massive surplus of electricity generation in SA from solar. A lot of it gets exported to Victoria, but often the wholesale price goes negative because there are no buyers.

As a result, SA has multiple offpeak windows and retail offpeak rates during the day that are lower than offpeak rates during the night. Some EV charging networks have stalls in SA where you can fast charge for free during certain hours of the day, because they get paid to take the electricity.

Solar feed-in tariffs in most markets here are also rapidly trending towards zero due to this effect. I get paid 2.5c/kWh.

 

[bradtem]

That already happens here frequently, at least at a wholesale level, particularly in South Australia which in 2023 achieved 71% renewable power purely on solar and wind.

During the day, there is often a massive surplus of electricity generation in SA from solar. A lot of it gets exported to Victoria, but often the wholesale price goes negative because there are no buyers.

As a result, SA has multiple offpeak windows and retail offpeak rates during the day that are lower than offpeak rates during the night. Some EV charging networks have stalls in SA where you can fast charge for free during certain hours of the day, because they get paid to take the electricity.

Solar feed-in tariffs in most markets here are also rapidly trending towards zero due to this effect. I get paid 2.5c/kWh.

Cool. Can you name a specific location or company where they are getting paid to take power in the day and thus give it out free. (Free charging stations are not that unusual, but mainly because they are there for other reasons that selling electricity.)

 

[Jules22]

Cool. Can you name a specific location or company where they are getting paid to take power in the day and thus give it out free. (Free charging stations are not that unusual, but mainly because they are there for other reasons that selling electricity.)

Amber, pretty much anywhere in Australia, I believe there are equivalents in the US, EU as well.