Advantages of installing higher power dual-module microinverters

APsystems

APsystems is now shipping the DS3 microinverter, which they tell us is the most powerful dual-module microinverter on the market. On this episode of The Pitch, Jason Higginson, senior director of marketing for APsystems, walks us through the spec sheet and some install scenarios for the highest power DS3 as well as the lower power DS3-S, DS3-L. We get into:

  • Specs of the three DS3 series microinverters
  • Comparing power with single solar module microinverters
  • Does it matter when I’m installing lower wattage modules?
  • Doing the math on component savings
  • Achieving better margins on each project
  • The new cooling topology

Watch the 15-min conversation right here. Part of the transcript is below.

How does the power of a dual module microinverter compare apples to apples to a single module micro inverter?

Higginson: With the DS3, we’re setting this record of 440 W output per channel, and what’s interesting is our development team was like, ‘hey with this new architecture and [the new] cool topology, we can go up to 960 with this thing,’ which is ridiculous. In the U.S., we don’t need that at this time, but we were able to do it, and they did it, so it sets this tremendous record.

The only thing we’re talking about here in the U.S. really is going to be that that 880 Watt version. … the DS3-S is 640 W, so per channel that comes out to 320, which is really for the installers that are used to using our YC600 where they have a lot of panels that they use that are lower than 400 watts. For the DS3-L, it comes in at 768 W, and then the DS3 is at 880, which we really see that more for commercial systems.

Does having ‘the most powerful’ dual module microinverter in the residential space make an impact even? Residential modules are much lower wattage than that, at least right now.

Higginson: When we first came up with this potential with this new architecture, we talked to many of our friendly installers and distribution partners about that, and they essentially told us it’s too powerful. Like, there is such a thing as too much power, and the market’s just not ready for that. So we dialed it back, and we came up with the DS3-L for lower power and the DS3-S.

But when we looked at the DS3-L, we found something interesting. On your typical residential system, on a 200 amp panel, many homeowner customers have 40 amps free or 20 for solar before they have to upgrade their panel, which is expensive. So if you have 40 amps available, most commonly, according to NEC code, you can only load 16 amps on this thing. So, we discovered that no matter how much dc you have on the roof, you have this output throttle which is limiting how much you can put onto each breaker. … so we worked the math backwards from that 16 amps to determine how much we can put onto each string and really maximize that.

That’s why we came up with that 768 W (for the DS3-L). It’s 384 per channel, and many installers like to use a 1.2 or 1.25 dc to ac ratio.

Am I gaining any advantages by going with the dual-module approach? Any other installation efficiencies that add up here?

Higginson: It’s worth noting that you have fewer inverters to purchase and fewer inverters that you need to stock, but most importantly fewer inverters to install on the roof. Think about that in terms of not just labor and reliability but also cost. When we look at using fewer inverters, if you look at the fourth line down, inverters per 20 amp circuit, we have five on ours.

APsystems DS3 L

But when we compare it to a traditional microinverter system like the very popular Enphase, it’s significantly more inverters. It’s three times as many components on the roof. Three times as many parts.

When you’re looking at the total output, they’re all fairly equivalent with the IQ+ versions that can hit those higher wattage modules. But if you look at the max PV module STC rating at the bottom, with the DS3-L, you can pair it with up to 480 W.

In terms of the actual cost all-in then, you’re paying for fewer microinverters and fewer modules but they are the higher efficiency, higher priced panels versus maybe the cheaper panels. So, what’s the sticker price comparison?

Higginson: That’s exactly what we’ve been looking at, and the higher wattage PV modules aren’t so significantly more expensive. The curve tends to flatten out at the higher end when we compare the same system output because of the sheer number of panels you have to put on the roof, the math comes out to significantly more. [there’s a slide showing this in the video].

Because you’re also paying less, you have a lower embedded cost, and you can either pass that on to the homeowner, or you can simply offer them what you were charging before and pocket that. That’s all profit.

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Our longer running side project is The Pitch -- in which we have awkward discussions with solar manufacturers and suppliers about their new technology and ideas so that you don't have to. We discuss everything from residential rail-less deck attaching and home solar financing to large-scale energy storage value stacking and utility-driven new home solar + storage microgrids.

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