Author: Perth Solar Force | Perth Solar Force
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East West Facing Solar Panels On A Single Inverter Input Can Work Well

Most Australian solar installations use string inverters where solar panels are connected in series with an electrical cable. Each group of panels in series is called a string. Each string is connected into a separate input on the inverter.

In the configuration above, each string can have a different numbers of panels and each string can face different directions. You could even have a different type of panel for each string. This is because each inverter input is connected to a separate Maximum Power Point Tracker (MPPT). The MPPTs optimise each input separately.

Sometimes multiple strings are connected in parallel, into one inverter input. To do this each string must have the same number of panels and they must be identical brands and models.

Generally speaking all the panels in the configuration above need to be facing the same direction, or the MPPT struggles to optimise the array efficiently.
If an east/west split of solar panels is desired, where some panels are facing east and some facing west, then normally those panels would be placed on separate strings and a two-input inverter would be used.

I Didn’t Believe It Myself At First

When I was told it was possible to put both east and west-facing panels on the same inverter input without a serious decline in performance, I was very sceptical. I was all, “Nah! That’ll never work!

When the sun isn’t directly overhead the two sets of panels will receive different amounts of light and, since they’re on the same input, the mismatch will cripple the MPPT’s optimisation and pull down the performance of the others. It’s not a good combination. Putting east and west-facing panels on a single input is like putting chalk and cheese together in a sandwich and hoping the contrast of flavours will result in a taste sensation.”
But I looked it up and it turned out to actually be correct, but only under the right circumstances.

Dietmar Is The Dude With The Dirt On Single String Shenanigans

When it comes to getting the low down on east/west splitting on a single inverter input, Dietmar Staudacher is the man to turn to. Or at least I assume he is a man. Very few women are called Dietmar. But I’m sure those women who are called that are quite impressive.

Dietmar wrote, Ost/West-Ausgerichtete PV-Anlagen Mit Nur Einem MPP-Tracker, and you can read a PDF of that paper in its original German here. Fortunately, I am extremely talented at reading German… after it has been translated into English. And you can read a translated PDF by clicking on its English title, Efficient East-West Orientated PV Systems With One MPP Tracker.

Now note that Deitmar’s paper was published 7 years ago, which is like 7 years in solar years. There have been a lot of developments since then. But his basic conclusions are still sound.

July Solar Feed-In Tariff Increase Roundup

Other electricity retailers have announced solar feed in tariff increases since AGL’s recent announcement – find out how much you could be getting for your solar power from July 2017.

Last week, AGL set the ball rolling by announcing it would be boosting feed in tariffs by up to 140%, stating the increases reflected rising wholesale electricity prices.

Here’s how the situation looks across Australia from the beginning of next month. We’ll update this post with information as it becomes available – Origin is expected to announce its new incentives in the next couple of days.

Solar Even More Financially Attractive

The changes will help absorb some of the brunt of increases to electricity costs from July; which affect both solar power system owners and those without. Between electricity price and FiT hikes, installing solar panels has become an even better investment. However, rising feed in tariffs don’t improve the economics of solar battery storage; an issue SQ blogger Ronald will discuss in more detail soon.


  • AGL : 10.6c (+77%)
  • Energy Australia: 11c (+83%)
  • Origin: TBA
  • Ergon Energy : 10.102c (+36%)
  • Diamond: currently 12c

New South Wales

  • AGL : 11.1c (+82%)
  • EnergyAustralia : 12.5c (+105%)
  • Origin: TBA
  • Diamond: currently 12c

On the 23rd of June, IPART announced its benchmark range for solar feed in tariffs in 2017-18 is 11.9c to 15c per kilowatt hour. It says the increase was mainly due to higher forecast wholesale electricity prices in 2017-18. The benchmark is a guideline, not mandatory.


  • No changes announced at this stage


  • AGL: 11.3c (+126%)
  • Origin: TBA
  • Diamond: currently 12c


  • On June 23, Tasmania’s Economic Regulator determined a solar feed in tariff rate of 8.929c per kilowatt hour for 2017/18 – an increase of 34% compared to 2016/17.

South Australia

  • AGL: 16.3c (+140%)
  • Energy Australia : 15c (+82%)
  • Origin: TBA
  • Diamond: currently 12c

Western Australia

  • No change at this stage

Northern Territory

  • No change – but the NT’s solar feed in tariff remains a the most generous in the country.

ABB UNO-DM-PLUS Inverter Available In Australia Next Month

It’s been a long time between drinks, but ABB’s new single-phase solar inverter – the UNO-DM-PLUS – will be available in Australia from mid-July.

Available in six power ratings from 1.2 to 5.0 kW, ABB says the UNO-DM-PLUS string inverter provides higher performance and all DM-PLUS models are the same compact size (553 x 418 x 175 mm). The new units, all of which weigh 15kg, offer a maximum efficiency of between 94.8% and 97.4%; depending on model.

UNO-DM-PLUS features plug-and-play connectors; so the cover doesn’t need to be removed. Combined with a commissioning wizard, these features lower installation time says the company, saving money.

An in-built user interface enables access to advanced inverter configuration settings, dynamic feed-in control and load manager; which can also be accessed through wireless communication.

Calling it “future-proof”, ABB says the UNO-DM-PLUS also features remote Over The Air (OTA) firmware upgrade functionality.

The new design wraps ABB’s quality and engineering into a lightweight and compact package, which thanks to intelligent technological choices means we have created an inverter solution which is optimized for domestic solar installations said ABB’s Giovanni Frassineti earlier this month.

ABB’s Aruba Microgrid Project

In other recent news from ABB, the company announced last week it will provide an advanced microgrid solution to the main power utility serving the Dutch Caribbean island of Aruba.

With a population of approximately 103,000 and a popular tourist destination, Aruba sources its electricity through a mix of thermal, wind and solar PV generation.

ABB’s solution will enable WEB Aruba N.V. to integrate more renewable energy capacity, while maintaining reliability and efficiency of power supplies – and meeting increasing demand for electricity

“The embedded software, automation and control technologies will also facilitate 24 hour forecasts and enable a stronger, smarter and greener grid,” said Massimo Danieli, head of ABB’s Grid Automation business.

Aruba is looking to free itself from the clutches of fossil fuel based power generation entirely and has set an interim goal of sourcing half its annual average electricity requirements from renewables by 2020. Currently, nearly 40 percent of the island’s electricity is sourced from clean power technologies.
Aruba’s largest solar power installation is a 3.5MW facility at Reina Beatrix International Airport, which consists of 14.000 solar panels.

Last November, Tesla signed a Memorandum of Understanding with WEB to supply Aruba with energy storage systems.