Tired of pumping energy into the grid

[mcart117]

First of all, hello to the forum and thank you for having me on board. I don’t think I’m a typical member. I am not a DIYer. I did physics at school so I understand Ohm’s law, but I am not practical. I am here to overcome the ridiculous constraints of Australian regulations and the profiteering of local solar contractors, and Tesla.

There are lots of things I don’t like about my current setup. First of all I have 6.5 kw on the roof but Australian regulations only allow me to pump in 5kva, so on a sunny day that’s 1.5kw of power going to waste. Second, in the summer, even with the 5kva choke, I am pumping over 20kwh a day into the grid for 7c/kwh, but when the sun goes down I pay 55c/kwh to get it back. Third, when the power goes out, the inverter turn right off, and I am left without power, even if the sun is shining.

So I’d like to store my surplus power, I’d like the battery in the circuit before the inverter so it can suck in the full 6.5kw from the roof, I’d like the battery to absorb power from the panels and power the house during a power cut, and I’d like to spend less than the AUD1000/kwh quoted by local contractors for a Tesla powerwall.

I’ve noticed from EV enthusiast websites that new EV batteries sell for under AUD200/kwh. Some people are powering their houses with 2nd hand EV’s; they seem to be mainly in the US, but it’s an option I’d like to explore. And Alibaba sell 3.2V 280aH “solar storage system” cells for around USD120-200/kwh.

So I’ll read what other people are posting, and then I’ll fire out some questions.

 

[robby]

Yeah I have had the bitter taste of finding out that the utility company would pay almost nothing for my power and yet it will power the houses of my neighbors and they will charge them full price from it!
I am making them richer on my equipment so I abandoned the idea of selling them power and added more batteries.

Building your own battery packs is not all that hard but considering the price of pre built rack mounted packs it might be easier to just buy those than play around with the slow shipping from China and the guess work involved in getting good cells. Also those cells will have no real warranty while the typical battery pack will have a 5-10 year warranty.

What model Inverter do you have? Only a few select models have full micro grid capabilities that allow it to stay on during a power outage. I wish I could help you with finding battery packs but I have no idea what is available in Australia.

At .55c/Kwh you would see a really quick payback on your system. Just some rough calculations tell me that in just about 3 years you would start seeing a profit on your investment.

 

[mcart117]

I have Fronius Primo 5.0-1-I and it just shuts down. I also have a smaller Growatt inverter ripped out of the previous system, but that is also designed to shut down when the grid is off, so unless someone knows how to hack it, it can't be used off-grid.

 

[Nobodybusiness]

I have Fronius Primo 5.0-1-I and it just shuts down. I also have a smaller Growatt inverter ripped out of the previous system, but that is also designed to shut down when the grid is off, so unless someone knows how to hack it, it can't be used off-grid.

You need to talk with some who knows Australian Law. We can tell you how but I have heard it’s no joke to mess with that stuff there.

 

[robby]

You need to talk with some who knows Australian Law. We can tell you how but I have heard it’s no joke to mess with that stuff there.

I have Fronius Primo 5.0-1-I and it just shuts down. I also have a smaller Growatt inverter ripped out of the previous system, but that is also designed to shut down when the grid is off, so unless someone knows how to hack it, it can't be used off-grid.

Yes I agree with @Biasjo. You guys have some of the most developed PV laws in the world with California and Hawaii being a close second. There are workarounds but you do not want to use them unless it's legal.
Power companies use algorithms in their billing systems that detect when your usage has dropped by more than xx% in three consecutive months. That automatically triggers an on-sight inspection.
If they find something that should not be there they will cut the power going to your house and deem it as unsafe for Linemen.

You might have to sell the Fronius which btw is a very good Inverter and get something on their approved list of all in one inverters.

 

[circus]

Maybe it'd be easier just to come up with a scheme to use power when producing and conserve when purchasing. Is power outages a problem? I purchased a $200 gas generator from the grocery store 15 years ago and had to use it once for an hour. Always starts if stored dry.

 

[mcart117]

OK, thanks for the replies. Here’s the thing.

I have a shed with a petrol generator wired to the house for use during blackouts (which happen quite often in remote country towns, and they go on for a while because we are not a priority for the repair crews). It is quite legal, having been installed by a licensed electrician. There is a switch on the main board, and during a power cut I manually pull the switch down to use the backup power supply, leaving the grid completely isolated.

I have 8 discarded 190W (5.21A, 36.5V) solar panels previously used with the Growatt inverter. I’d like to put them on my shed, use them to charge a battery put together with help from this board and elsewhere, and use the “doctored” inverter to power the house, not only during power cuts, but also on any day after the sun goes down. It will be a bit of a chore manually throwing the switch on the main board twice a day, but I want to do it as a proof of concept on alternative battery technologies.

I'm not in a rush. I’m reading about batteries and what other people are doing. This post was really about saying hello and letting you all know where I am coming from and what my mission is. After I’ve done some more reading, I’ll post more specific questions, hopefully in the right place.

 

[mcart117]

This is the shed I was talking about. The roof facing the cam faces north, which is where the sun comes from in Australia.



These are the panels I want to put on the roof of the shed.



This is the inverter. Someone on another forum said they could help me convert it to an offgrid inverter. Not sure how easy that would be. I'd probably break it. Might be better to try and sell it on eBay and by another one.



This is my petrol generator. The cable plugs into my house circuit. When I have converted or replaced the inverter, that would plug into the same place. The petrol generator could then be sold to a Luddite.



This is the switch between the mains grid and the shed circuit. It will be a pain switching to the shed at 3:00 pm every afternoon and back to the mains at 9:00 every morning, but the idea is to test out and prove the batteries before fiddling with my existing on-grid solar setup.

 

[WolfBarn]

First of all, hello to the forum and thank you for having me on board. I don’t think I’m a typical member. I am not a DIYer. I did physics at school so I understand Ohm’s law, but I am not practical. I am here to overcome the ridiculous constraints of Australian regulations and the profiteering of local solar contractors, and Tesla.

There are lots of things I don’t like about my current setup. First of all I have 6.5 kw on the roof but Australian regulations only allow me to pump in 5kva, so on a sunny day that’s 1.5kw of power going to waste. Second, in the summer, even with the 5kva choke, I am pumping over 20kwh a day into the grid for 7c/kwh, but when the sun goes down I pay 55c/kwh to get it back. Third, when the power goes out, the inverter turn right off, and I am left without power, even if the sun is shining.

So I’d like to store my surplus power, I’d like the battery in the circuit before the inverter so it can suck in the full 6.5kw from the roof, I’d like the battery to absorb power from the panels and power the house during a power cut, and I’d like to spend less than the AUD1000/kwh quoted by local contractors for a Tesla powerwall.

I’ve noticed from EV enthusiast websites that new EV batteries sell for under AUD200/kwh. Some people are powering their houses with 2nd hand EV’s; they seem to be mainly in the US, but it’s an option I’d like to explore. And Alibaba sell 3.2V 280aH “solar storage system” cells for around USD120-200/kwh.

So I’ll read what other people are posting, and then I’ll fire out some questions.

Hi I am New to the Forum But have some Experience in Solar Off Grid
Abandon any idea of selling power I believe they wont even be taking it from you Soon & will Charge to input from solar in Australia

 

[wattmatters]

I believe they wont even be taking it from you Soon & will Charge to input from solar in Australia

That's complete nonsense.

 

[brum]

It is the same by default here in Bulgaria. If you don't sign a specific contract with the grid operator (and the process is ridiculously complex + it requires you to become a legal entity) you are staying with the default energy meter. And the default one measures the power that goes through it ignoring the direction of the power. So if you push 10kWh energy to the grid they will charge you like you have used 10kWh energy from the grid.

That's why I'm going with a limiter so no energy is being pushed to the grid. It is cheaper for me to lose part of the energy instead of selling it.

 

[WolfBarn]

That's complete nonsense.

Not arguing
Just a matter of time for them
https://www.theguardian.com/austral...ouseholds-to-send-rooftop-solar-power-to-grid

 

[wattmatters]

There are lots of things I don’t like about my current setup. First of all I have 6.5 kw on the roof but Australian regulations only allow me to pump in 5kva, so on a sunny day that’s 1.5kw of power going to waste.

It's not going to waste, it's just not produced. There is only a limited time on good solar days that an array can produce anything close to its rated maximal output capacity.

Secondly, your inverter can only output 5kW. "Over panelling" a solar PV inverter is a normal, sensible and deliberate strategy and represents good solar PV system design.

It so happens that in Australia the most common over panelling ratio of DC:AC is close to 133% as that is the upper limit set for the solar panels to qualify for the federal government's Small scale Technology Credits (STCs), which significantly lower the price of installing the system in the first place. In effect the PV panels from 5kW to 6.6kW are free, and then some.

They enable the system to produce more overall, in lower light conditions and in seasons where the solar PV output is reduced. Clipping is relatively rare and "lost production" for such a DC:AC ratio is pretty small overall. It might be a few % at best.

In most parts of Australia, there is a limit on the amount of grid tied solar PV which can be connected per phase, and also a limit on the maximum power which may be exported per phase. This is a sensible and reasonable restriction to ensure the grid can manage to accept all that distributed energy resource. We do have a solar PV system on nearly 30% of all homes and the grid needs to be able to manage all that energy excess.

Count yourself lucky to have a 5kVA limit while being in a rural area. My limit is 3kVA/phase.

Second, in the summer, even with the 5kva choke, I am pumping over 20kwh a day into the grid for 7c/kwh, but when the sun goes down I pay 55c/kwh to get it back.

Where in Australia are you? It would be pretty unusual to be forced to have a tariff regime like that. Do you know which electricity distributor (the poles and wires company) services your area?

Third, when the power goes out, the inverter turn right off, and I am left without power, even if the sun is shining.

Yes, that's correct - it's not only the law, the immediate isolation of such systems is for the safety of everyone working to resolve the problem with the grid supply. If you mess with this, you may kill someone. It's REALLY important not to have live power output connected to the grid during grid outages.

The manual transfer switch you have performs the function of ensuring your generator supply can never energise the grid. Any alternative off-grid supply will also need the same sort of isolation. It could as you point out be the exact same power inlet and transfer switch.

I built a small solar PV and battery off-grid system which I use for grid outage backup. It supplies power to the home via the same sort of transfer switch you have.

What sort of system you go with may depend somewhat on your energy and power needs, and also your budget. Yep, commercially installed batteries such as the Tesla are very expensive, and in Australia unlikely to be financially rational.

I have Fronius Primo 5.0-1-I and it just shuts down.

As it should. My Fronius grid tied system also goes offline during outages.

The Fronius is a dedicated grid tied inverter, it is not designed for off-grid operation.

It is possible however to have them operate off-grid but they need to be controlled by another grid-forming inverter which uses frequency control to manage the output of the Fronius. No matter which way you cut it, that is not cheap. It's the same process the Tesla Powerwall uses to enable such PV systems to operate off-grid during outages.

There are many solution options, some which are not that expensive if you know what you are doing. Which option(s) is(are) suitable depends on what your energy and power demands are, budget and knowledge of how to make it all safety operate.

The first thing to do is to perform an energy audit. Be clear about what it is your need to supply power to, what their power and total energy demands are and when that energy needs to be supplied, and what sort of duration of grid outage you are seeking to cover for.

Then some options might become somewhat clearer.

One option for instance is to add an off-grid hybrid inverter with its own solar PV array on your shed and a battery. It can also accept an AC input which can be the grid but also your generator as an alternate supply. Such a system can be made to pass through power from the grid or to supply from its own solar PV and battery - and flipping between each can be automated to some extent.

 

[wattmatters]

Not arguing
Just a matter of time for them

Rather than read that stuff, how about reading the actual proposal?

When you do you'll see that:
- none of the tariff structures which include such export charges will be compulsory. Everyone may opt out. Opting in however comes with significant benefits
- they require the networks to improve infrastructure to support the addition of more solar PV and to remove or raise solar PV connection and export power limits
- they also require an equivalent reduction in charges for importing energy (all such proposals are required to be revenue neutral)
- they are also required to be assessed and passed by the national regulator after extensive consultation with various groups including end consumers

 

[wattmatters]

It is the same by default here in Bulgaria.

It's not like that at all in Australia. No one is going to be forced to be charged for exporting to the grid.

If in future there are any such charges to tariff structures, they will be at the network wholesale level (distributor bills the retailer), not directly at the consumer level. All that might happen in some instances is the feed-in tariff offered by retailers is a little lower, but in return the import tariffs will also be lower.

Edit: I added a clarification in italics

 

[wattmatters]

For anyone so interested, here are the details on what is actually being proposed by the Australian Energy Regulator:

Draft decision

www.aer.gov.au

Get beyond click bait headlines and instead take some time to read and understand what's actually being proposed. Frankly it's a sensible course of action as our grid goes through a tremendous transformation away from centralised coal power supply to renewables and will support the continued growth of rooftop solar PV in Australia as well as ensure some basic consumer protections.

 

[mcart117]

Many thanks for your reply.

Where in Australia are you? It would be pretty unusual to be forced to have a tariff regime like that. Do you know which electricity distributor (the poles and wires company) services your area?

Western Australia. We have only one distributer. My package "smartpower" charges a lot for the peak time of 3-9pm but much better rates overnight, when we usually have evap air con or fans running, or inverters to heat the kids room in the winter.

I built a small solar PV and battery off-grid system which I use for grid outage backup. It supplies power to the home via the same sort of transfer switch you have.

I am interested that you have an off-grid solar backup system.

The first thing to do is to perform an energy audit. Be clear about what it is your need to supply power to, what their power and total energy demands are and when that energy needs to be supplied, and what sort of duration of grid outage you are seeking to cover for.

I have been keeping a spreadsheet of energy consumed and exported since the solar panels were intalled 3 years ago.

One option for instance is to add an off-grid hybrid inverter with its own solar PV array on your shed and a battery. It can also accept an AC input which can be the grid but also your generator as an alternate supply. Such a system can be made to pass through power from the grid or to supply from its own solar PV and battery - and flipping between each can be automated to some extent.

That sounds like an interesting end phase solution. For now I am gearing up to experiment with LifePO4 cells offgrid, just to get to know the technology better.

Thanks again for your thoughts.

 

[mcart117]

Hi I am New to the Forum But have some Experience in Solar Off Grid
Abandon any idea of selling power I believe they wont even be taking it from you Soon & will Charge to input from solar in Australia

Thanks for the reply. I may well come back to you with questions. I was in the electronics club at school and often burnt out transisters by shorting them out, so this is all well outside my comfort zone!

 

[mcart117]

Not arguing
Just a matter of time for them
https://www.theguardian.com/austral...ouseholds-to-send-rooftop-solar-power-to-grid

That's an interesting article - love the Guardian.

But if too much electricity is being pumped into the grid by domestic solar arrars, why are they still building solar farms like this one in Merredin, WA?

Panels - Merredin Solar Farm Powered by SUN Energy

Risen Energy Panels The Merredin Solar Farm consists of approximately 360,000 Risen Energy 370W high performance monocrystalline PERC module panels mounted on a single axis tracking system. 22 Inverter stations converts the power from the solar panels to alternating current (AC) before entering...

www.merredinsolar.com.au

 

[wattmatters]

Western Australia

That explains it. Not much choice over there unfortunately.

I am interested that you have an off-grid solar backup system.

I wrote about it in this thread:

Backup down under

Greetings from down under. I live in a home near the small town of Bellingen, in northern NSW, Australia. Glorious country: That's our home at left centre, and obscured by the tree and slightly off the left of the image is a secondary dwelling where my Mum lives. 12 acres, behind our home (to...

diysolarforum.com

But if too much electricity is being pumped into the grid by domestic solar arrars, why are they still building solar farms like this one in Merredin, WA?

Last year fossil fuels supplied 68% of the electrical energy demand in the WA grid. Solar PV 15%.

Utility solar is tiny in comparison to other sources of supply, which considering the fantastic solar resources in WA suggests there is a LOT of room to grow grid scale solar PV.