{"id":75181,"date":"2023-12-13T07:08:53","date_gmt":"2023-12-12T21:38:53","guid":{"rendered":"https:\/\/www.solarquotes.com.au\/blog\/?p=75181"},"modified":"2023-12-28T08:57:35","modified_gmt":"2023-12-27T23:27:35","slug":"solar-inverter-current-dilemma","status":"publish","type":"post","link":"https:\/\/www.solarquotes.com.au\/blog\/solar-inverter-current-dilemma\/","title":{"rendered":"The Solar Inverter Dilemma: Struggling to Match Modern Panel Output"},"content":{"rendered":"

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Solar panel technology has made incredible strides in recent years, significantly boosting rooftop energy production. Solar panel manufacturers have achieved this mostly by optimising their panels to push out more current than ever before.<\/p>\n

But this progress has given rise to a challenging situation: the world of solar inverters<\/a> is struggling to keep pace. Finding inverters capable of effectively managing the increased current output of modern solar panel arrays has become increasingly difficult.<\/p>\n

Read on, and I’ll explain the challenges posed by high DC string currents and discuss the urgency for inverter manufacturers to catch up on current specifications or push back on panel makers to turn their ever-increasing wattage into more voltage.<\/p>\n

This post is technical. If you are reading this as a lay person – you may want to skim the more technical stuff and just get a feel for how much can go wrong in solar system design and why a good installer matters – especially with modern, high-power solar panels.<\/p>\n

The Challenge of High DC String Currents<\/h2>\n

Making solar inverters handle higher currents is difficult and expensive because heat increases with the square of the current: P=I\u00b2R.<\/p>\n

Fronius inverters<\/a>, with their active temperature control fan, blow off heat, run cooler, yield more power, and have a higher current-handling capacity. In contrast, a random competitor like SoFar<\/a> addresses heat issues by incorporating a large alloy heat sink and attaching a warning sticker about the unit being hot to the touch!<\/p>\n

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Here you can see the Fronius is running cooler than the passive inverter next to it because the heat is streaming out of the top, actively driven off by a fan.<\/p><\/div>\n

So, while I think it would be helpful for panel makers to revert to higher voltage, lower current solar panels<\/a>, at the end of the day, it’s the solar inverter manufacturers who are going to have to catch up if we’re to avoid problems with panels that are currently on the table.<\/p>\n

Many Inverters Now Can’t Handle A Parallel Array<\/h2>\n

Many roof designs require two strings of solar panels<\/a> connected in parallel. When you parallel two strings, you double the current from the solar panel array.<\/p>\n

Right now, unless you specify a commercial-sized 3-phase inverter in the 15-30 kW range, few domestic inverters can effectively handle the current from parallel arrays.<\/p>\n

This leaves designers hamstrung when they try to get big systems built using high-current panels. If you want a maximum-effort power system, you must buy two inverters.<\/p>\n

As the solar industry progresses, inverter manufacturers must rise to the challenge.<\/p>\n

Hurrah For Enphase IQ8<\/h3>\n

At least Enphase microinverters<\/a> finally have a solution with the release of IQ8 series<\/a>. Rated for 360 or 384VA they can handle 37% more current… and that directly equates to yield.<\/p>\n

When you’re comparing 360VA IQ8ac at 14 amps,\u00a0 and 366VA IQ7a<\/a> at 10.2 amps, the similar VA (wattage) ratings are shown up as a bit misleading and that has caught out some less than observant installers.<\/p>\n

REC Panels Allow More Design Flexibility<\/h2>\n

As we outlined recently, REC<\/a> has now released the latest iteration of the Alpha Pure<\/a> range. The new RS variant is a whacking 470-watt panel (with an enormous 1205 mm width), but the best part is the voltage. REC has made their new model with 88 cells instead of 54, allowing for better shade tolerance and more voltage.<\/p>\n

Solar panels like this tip the scale back into your favour because if we take an average 6.6 kW system, the panels can be more flexibly deployed on a challenging roof or simply run at higher efficiency if the space allows a simple layout.<\/p>\n

Take the high current\/low voltage Jinko<\/a> Tiger Neo JKM470N-60HL4 with the following specifications:<\/p>\n