How To Beat The Solar Oversize Rule With Solar And Batteries

Breaking the well-known ‘133% Photo voltaic Oversize Rule’ will not get you into hassle in the event you add a battery. Or can it?

Relying on who you ask…

However earlier than we get to that, a short historical past of the rule.

The Australian Photo voltaic Panel Array Oversize Rule

Why are photo voltaic firms all over the place providing 6.6 kW photo voltaic as their customary provide?

That is due to the foundations. Or, to be extra particular, the “Clear Vitality Council Pointers For Grid-Related Photo voltaic PV Programs (With out Storage)”. It is a set of pointers that must be adopted when designing and putting in solar energy techniques.

In case your photo voltaic designer doesn’t observe them, you’ll not be eligible for STCs on the system. In different phrases, you will not get the ‘photo voltaic rebate’, and your system can be hundreds of {dollars} costlier.¹.

We’re particularly speaking about “Guideline 4.4: Array peak energy – inverter sizing”:

4.4.1 To facilitate the environment friendly design of the PV system, the inverter nominal AC energy output will not be lower than 75 % of the array peak energy and it isn’t outdoors the utmost allowable array measurement specs of the inverter.

The primary a part of this rule is vital right here: “the inverter nominal AC energy output not doable lower than 75 % of array peak energy”.

Or, to place it one other, extra intuitive approach…

The photo voltaic panel array doesn’t exceed 133%² of inverter measurement in kW.

Historical past of ‘The Oversize Rule’

Again within the previous days of photo voltaic, shortly after the Renewable Vitality Goal was conceived, the Small Know-how Certificates (STC) scheme was invented as a technique to separate monetary incentives for giant (100 kW +) and small photo voltaic techniques based mostly on their theoretical. carbon discount. It was really a carbon tax launched by John Howard, however fortunately the troglodytes had been by no means shiny sufficient to comprehend it or silly sufficient to politicize it.

If you happen to set up a photo voltaic thermal scorching water unit, warmth pump scorching water or photo voltaic PV, there’s a worth connected to the discount of greenhouse air pollution. You receives a commission upfront for the coal and gasoline you will not burn from now till 2030.

STCs for photo voltaic are based mostly partially on what number of watts of photo voltaic panels are put in. However what in the event you set up extra kilowatts of panels than the inverter is nominally rated for? That can lead to fewer kWh of power per kW of panels put in than a photo voltaic array equal to the output of the inverter.

Bureaucrats hate anomalies like that, so it was determined to restrict something over 133%. By their judgment, 133% will use the {hardware} effectively and supply the very best effectivity when it comes to cash spent for carbon abated.

The factor is that photo voltaic inverter producers all the time rated their machines for greater than 133%. You’ll be able to wire 150% and even 200% of the inverter’s nameplate capability, and it’ll function nearer to its most throughput for a lot of its life.

After all, there are intervals of fine insolation when the inverter will not be capable of deal with all of the out there power, it’ll clip the output, which is able to run for an hour or two in the course of the day. However for a lot of the day the inverter will go extra helpful power than a non-large system.

‘The Rule’ Is Previous Its Promote-By Date

Earlier than CEC, SEIA was the native business physique. It’s a union of like-minded professionals who put collectively a regular, coaching and analysis panel, which in flip wrote a doc entitled “Recommendation on Finest Apply”. It is a well-meaning ‘code of conduct’, circa 2007 tweaked by 5% and adopted by the CEC as a tough rule with out additional scrutiny.

The CEC members web site hyperlinks to a doc that explains the rationale behind the rule. The newest model is dated February 2013.

Justifying the rule, it says:

“We consider this restrict will enable the absolute best design for many instances whereas nonetheless permitting flexibility.

At this worth, techniques put in in the very best orientation and tilt angle is not going to undergo yield loss and in addition enable some extra to compensate for losses because of poor areas to put in. “

Sadly, this rule informs from a time that:

• There are 10 x small rooftop photo voltaic put in in Australia.
• The price of photo voltaic is 2-3 instances increased than at this time.

And virtually each drop of candy photo voltaic power put in up to now has instantly offset fossil fuel-based electrical energy technology.

Quick ahead 10 years, and maximizing the yield of your system in the course of an ideal day within the solar will not be that vital. There may be all the time lots of photo voltaic electrical energy generated throughout these instances when wholesale electrical energy costs are unfavourable. That is the grid’s approach of telling you there’s an excessive amount of power within the system.

When the grid actually wants your photo voltaic to pump out extra power than within the winter, on cloudy days and early and late within the day – that is precisely when glorious techniques ship.

However due to the previous 133% oversizing rule, photo voltaic homeowners are restricted to a photo voltaic array that’s 133% bigger than their DNSP (native electrical energy community) mandated most measurement of inverter. That is often a small 5 kW inverter per section.

Which fits to the purpose I have been making for 15 years now: I’ve by no means met a buyer who complained they put in an excessive amount of photo voltaic.

What Does Oversizing Photo voltaic Should Do with Batteries?

Properly, to cite Tom from Clear Vitality Council lately,

“That is an attention-grabbing one.”

You probably have a house battery linked to your photo voltaic set up, now you can exceed the 133% most rule and go to the really helpful capability of the complete inverter producer. Which means you possibly can declare the STC incentive cost for 150% or 200% of the inverter’s nameplate capability.

So the CEC Set up Pointers with the ‘133% rule’ are “For Grid-Related Photo voltaic PV Programs (No Saving)“. The suffix is ​​current.

So, a 5 kW photo voltaic inverter with battery is not restricted to six.666 kW linked photo voltaic panels. There might be 7.5 kW or 10 kW photo voltaic linked.

In case you are fortunate sufficient to have a DNSP that permits a ten kW inverter with a 5 kW export restrict, with a battery you possibly can join 15 kW and even 20 kW in a single section.

That may be a profit for photo voltaic power output within the morning, night, winter and in dangerous climate.

Feels like a winner, does not it? Sure, however it’s photo voltaic, and the foundations are sclerotic.

CEC advised us that the directions they write and monitor technically point out the inverter not exceeding 75% of the capability of the array (the reverse of 133%), and that ratio is what’s vital to them. They particularly level to the entrance web page of the doc which states that batteries should not thought-about the place photo voltaic PV capability is anxious.

So, the CEC is not going to present any assurance {that a} battery system over 133% will qualify for STCs (AKA the photo voltaic rebate).

I Swear, This: ¯_(ツ)_/¯ ..Wants A New CEC Emblem.

That is Clear Vitality Regulator which really has legislative energy. They make the determinations, and it’s at their discretion that techniques claiming greater than 133% are authorized. After I requested for an evidence from Peta at CER, she referred me to Tom at CEC which is the physique they use for technicality. I used to be advised that the CER doesn’t have sufficient technical experience.

What?

It is a query that others within the photo voltaic business ask, and I do know not less than one installer who enthusiastically pursues some clarification till he will get a “definitive” reply a few level. He happy himself that the CER would enable extra STCs to be made for hybrid battery inverters, however not for techniques that use AC-coupled batteries such because the Powerwall³.

Many installers select their expertise mixture and submit the paperwork to the STC vendor/aggregator and receives a commission when it is carried out. However they threat the system being deemed non-compliant and the complete STC payment should be returned⁴or they have to argue the purpose.

This sort of ambiguity drives individuals away from the photo voltaic business.

If you happen to assume the 133% oversize rule is ineffective, then please ship an e-mail to:

[email protected]

Feedback are open till tomorrow (December 6) however could also be accepted after that, on the discretion of the CER.

Personally, I might similar to to see them pay STCs at full inverter spec, or not less than allow you to declare 133% after which set up the additional capability you need with out shedding the all STC payment.

Giant Photo voltaic With Batteries Can Assist Ship Extra Photo voltaic When It is Wanted Most

We have to set up extra photo voltaic panels with good inverter capability to supply:

1. extra energy within the morning and night, whereas the output can be lower or throttled at midday.
2. extra energy as much as the DNSP export restrict for a lot of hours of the day.
3. extra energy extra worth to you, the shopper.
4. extra energy, greater than the DNSP export restrict, to cost the battery (relying in your design).

So let’s hope that CEC and CER lose the 133% oversize bond of the previous. A couple of hundred emails from you’d assist loads.

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