Food for thought. I do not know how production is calculated down under but here in Mexico it is calculated based on the world solar day rating for the area which is 4.5 hours. We have a number of systems installed with Enphase IQ7+ and JA Solar 375-watt Mono panels. Our average production (base on 60 day billing from the electric company) is 2 kilowatts per panel per day. This is substantially higher than the area rating for the panels ( 375 x 4.5 = 1.687 kilowatts) and we have seen production as high as 2.25 kilowatts on many days. In fact, our testing and the information from Enphase lists the perfect panel size for the IQ7+ at between 360 and 385 given our solar day.
I am constantly having to teach people that they should look at average daily system production - not peak performance when deciding on a system. Clipping is an issue, however, if you get a longer and more consistent production day then you will have higher total average production. Given the two choices - 370-watt panel and 345-watt panel, I would go with the 370. My only rider on that is to check with the studies done by Enphase and match their real world results to your climate conditions. They have done testing in many locations and have all the stats based on micro-inverter size and panel size.
Thanks @mexicansolarguy for the explanations, I like the 370w panels as well, but from the guys that giving me the quote, he mentions there are not much benefits to got with the NeON R 370 (18 panels) compared to the NeON 2 350 (19 panels) with enphase iq7+, cause it will give the same 295w output per panel.
For 20w differences, is that worth the money?
Our system comps. show a difference of about 1 kw per day on average with 9 - 12 panel systems when using IQ7+ and 340-watt panels vs IQ7+ and 365-watt panels. Given you system size, you could see between 1.5 and 2 additional kilowatts per day. The question for you is - Does the additional cost per panel justify an additional 500 - 700+ kilowatts per year? Here is one other point to consider, and this is for anyone considering micro vs string and different panel sizes, as panels age they lose productivity. This productivity is lost at the top end of the panel wattage. A 400 watt panel in 10 years will be maxed at 380. So when you buy the micro-inverter you do not have to worry about the top end loss of production, your system will maintain max production for years to come based on the throughput of the micro-inverter. String inverters depend on getting to their max as much as possible to get their total daily output and as the panels age the production diminishes. Micro inverters depend on getting to their max power output sooner and staying there longer through the day - so with a 370 watt panel you will get to max sooner that with a 350 watt panel and you will achieve the same or better results with 1 less panel and one less micro-inverter and a little less labor for the install.
Sorry reread your post and saw you re looking at 18 of the 370 and 19 of the 340. The production will be about the same, however, you will use more roof space, more racking, and additional panel and micro-inverter with more labor for the install. I am always looking to condense a system, not expand the system (for the same power output). While the micro’s are really dependable,18 is one less to have a chance of a problem. I do not know what pricing is like down your way but, I know it would be less expensive here to pay the additional cost for the bigger panels vs all the add in costs of one more smaller panel and the micro and the racking and the cable and the labor for the install.
Hi guys, late to the party but wanted to add that going for a system above 5kW for inverter rating on a single phase is still possible and may not have such a big impact on your savings.
From our experience in Sydney, Endeavour has always limited single phase connections to 5kw export but Ausgrid have most often approved more than 5kw export.
Using IQ7+ micros, export limitation is built in when commissioning the system without additional costs.
Coming back to your savings, if you’re expecting to have high solar self consumption you may very rarely actually have above 5kWh to export and this is the best case for going for a bigger system on a single phase. In the case that your solar self consumption is low, you risk losing some savings during the summer months from your lost solar exports (clipping).
To put it in perspective, on a 21c feed in tariff, lets say you lose 6kWh of export each day for 3 months (This would be typical for a 10kW system by panel rating). This adds up to around $115 in lost savings each year. BUT you will also have more generation in the morning and evenings, around 6kWh for a 10kW system compared to a 6.6kW system. If you’re able to self consume that extra solar during that same 3 month period, using a flat rate of 29c for electricity, you stand to save around $158. When you include the extra generation for the other 9 months of the year, it seems a good choice to go for the bigger system with export limitation.
I hope that makes sense - keen to hear what others think.
Some more questions about the Maxeon 395w and the Enphase IQ 7x. I’m about to buy 12 Sunpowers 395w preferable with Enphase. I’m aware the panel is out of spec for the IQ 7X. But an installer here in the Netherlands suggests it works fine together, just one thing that’s out of spec. The IQ 7X max input DC voltage is 79,5 V, Sunpower 395w maximum Open Circuit Voltage (Voc) is 75.4 V. But this is at 25 degrees Celsius test-conditions. Let’s say at 0 degrees Celcius (cold sunny day) it is 4.4 volt higher (25x176mv (voltage temp Coef.)=4,4 volt) together makes 79.8 V so out of spec. This means when for some reason the panels are switched off at that moment they will not restart. This is more of a theoretical thing since the panels start in the morning when the output is way less. The installer claims he has several projects done this way without any problems. Is there anything else to consider? I’m not technical (electricity wise) at all so I find it hard to judge. What are your thoughts? Thanks in advance and sunny greetings from the other side of the World.
Can I get an insight from pairing the High wattage panels with the IQ7+ enphase micro-inverters. What is the maximum power output per hour per panel through them?
Thanks for the reference @Marty. Greatly appreciate the insight. I was quoted by a few companies on a 10.08kw system (28 X 360w LG Neon 2) by most but the latest and best company have 34 LG Neon 2 panels with IQ7+ micro-inverters.
Glad to have quality installers out there who do sight inspections etc.
