Request for input on solar proposal - Q Cells and Enphase Microinverters

[SunEagle]

I had my system installed, 20 g-6 Q-cell 340 watt panels with enphase IQ7+ inverters from a company that has been in business 30+ years. 10 year labor warranty on inverter replacement and 25 on panels. End price after tax rebate was 1.70 a watt, if you want to get technical 1.96 per watt due to inverter max output of 295 watts.

Where I live in Florida I have never gotten a quote for less than $3/watt for any micro inverter system. Even a string inverter seems to cost more than $2/watt which makes a payback of more than 12 years for me. It is hard to justify a system that will cost me more than $15k that may last longer then my life since I am now over 68 yo.

But to those that have a high electric cost or companies that will install for less then $2/watt I say go for it. Just don't be fooled with any long warranty that they state because most companies will not be around that long or end up just charging you to replace failed equipment.

[J.P.M.]

I had my system installed, 20 g-6 Q-cell 340 watt panels with enphase IQ7+ inverters from a company that has been in business 30+ years. 10 year labor warranty on inverter replacement and 25 on panels. End price after tax rebate was 1.70 a watt, if you want to get technical 1.96 per watt due to inverter max output of 295 watts.

Which is nice but anecdotal and means you'll have the additional probability of 20 optimizers to deal with when/if they fail that a simple string inverter would avoid as well as the hassle and expense of getting at them, especially the ones that aren't on the edges of the array. More stuff to fail. KISS applies.

I wouldn't feel overly confident about a company staying in business. Any company can go belly up. More anecdotal stuff: One of the most reputable and reliable companies in San Diego appears to have gone belly up after 17 years in business. They were one of 3 I considered when I designed my system and did consistently high quality work.

As for how to figure specfic, the usual and customary way to express specific price in the U.S. is total system price in $$/STC watt of the modules. Figuring specific price in ways other than that just muddies the waters and opens a path to confusing B.S. from peddlers.

[wetsu151]

I had my system installed, 20 g-6 Q-cell 340 watt panels with enphase IQ7+ inverters from a company that has been in business 30+ years. 10 year labor warranty on inverter replacement and 25 on panels. End price after tax rebate was 1.70 a watt, if you want to get technical 1.96 per watt due to inverter max output of 295 watts.

[J.P.M.]

Seems to me, after knocking around here for 8+ years, that in general, those posting on this forum who see string inverters as having advantages over micros or optimizers are those who are more knowledgeable and have more practical experience about and with PV, while those who favor micros and optimizers are less so.

If I had as much as an eyeball and a balloon knot and was in the market for residential PV, that would probably influence my choice.

[nerdralph]

Our string inverters take 5 minutes to swap out, we keep a loaner unit in stock and the manufacturer replaces that and pays us well for the truck roll. String inverters are honest about their 10 year warranties. Microinverter companies are scamming the public with their claims of 25 year reliability.

I do the same thing. I mainly sell 5, 6 & 7.6kW inverters, so I just keep a 7.6kW as a spare.

[SunEagle]

Some failures would always happen, no matter what. Enphase eliminated labor reimbursement for replaced microinverters when the company was in danger of folding. It did make sense since nobody else had the same policy.

There is some disagreement in this thread on the expected lifetime for microinverters but there is something that everyone agrees on. Some microinverters will fail within 25 years warranty window. My opinion is that percentage of failed units is so small that it is almost ignorable, I.e if I have 100 IQ7s in in my system and 1 fails after 15 years I would not even bother to replace it. Contrast it with a failure of a string inverter with common turnaround time for having replacement installed measured in weeks or even months.

I would say there are people that may or may not agree with you and they are the ones that install the equipment.

As for me the cost of installation for the micros is much more then the cost of a quality string inverter. But again to each their own business on what they want to spend or deal with.

[solarix]

I've had a couple Enphase systems where over 50% of the units have had to be replaced and quite a few SolarEdge systems where we replaced all the optimizers. (Of course, this is in Arizona) Fortunately, most of these were on tilt racked arrays where the replacement wasn't so bad. At least on the SolarEdge jobs we were paid for the labor. We had to charge the Enphase customers whose original installer would either not serve the customer or was out of business.
Our string inverters take 5 minutes to swap out, we keep a loaner unit in stock and the manufacturer replaces that and pays us well for the truck roll. String inverters are honest about their 10 year warranties. Microinverter companies are scamming the public with their claims of 25 year reliability.

[Will792]

Two. And why did they discontinue replacement labor fee ? I mean if they are good for 25 years, they'd never pay out a nickel !

Some failures would always happen, no matter what. Enphase eliminated labor reimbursement for replaced microinverters when the company was in danger of folding. It did make sense since nobody else had the same policy.

There is some disagreement in this thread on the expected lifetime for microinverters but there is something that everyone agrees on. Some microinverters will fail within 25 years warranty window. My opinion is that percentage of failed units is so small that it is almost ignorable, I.e if I have 100 IQ7s in in my system and 1 fails after 15 years I would not even bother to replace it. Contrast it with a failure of a string inverter with common turnaround time for having replacement installed measured in weeks or even months.

[Mike90250]

I do not agree with this opinion. It is a fact that many conventional inverters would not last 25 years but most Enphase microinverters will stay functional for 25 years based on modeled MTBF and components they use. At the same time Enphase no longer pays replacement labor fee, when failed units are replaced. I think it used to be $70 for each replaced unit.
Models starting from M215 have been extremely reliable. I would be more worried about SE power optimizers.

I don't buy your statement
One, I did MTBF failures for spacecraft for +30 years. I highly doubt any roof top microinverters will be functional after 25 years. Using the VERY BEST space certified gear, it's difficult to get more than 15 years at operational specs. Things may continue to work but in a degraded condition. Power handling equipment is ever less reliable. And I can play in SPICE and make nearly anything come up at 25 years. I honestly suspect they "fudged it" to get 25 years.
Space environment is actually much more controlled with all the thermal control on the spacecraft buss, but roof tops can go from below freezing to over 140F daily

Two. And why did they discontinue replacement labor fee ? I mean if they are good for 25 years, they'd never pay out a nickel !

[J.P.M.]

That's a false dichotomy. I think the most reliable option is a string inverter. Even in jurisdictions that require module-level rapid shutdown, something like the RSD-S-PLC is a simple and low parts count module compared to optimizers or microinverters.

FWIW, +1. fewer parts, less stressful environment, KISS applies.

[nerdralph]

Models starting from M215 have been extremely reliable. I would be more worried about SE power optimizers.

That's a false dichotomy. I think the most reliable option is a string inverter. Even in jurisdictions that require module-level rapid shutdown, something like the RSD-S-PLC is a simple and low parts count module compared to optimizers or microinverters.

[Will792]

Realize that microinverters will not last the 25 years they are warrantied for. The manufacturers do this warranty as a ploy to match the 25 year warranty of the PV panels (which will last 50 years) They will replace the microinverters under warranty but you need to be clear about who is going to do the replacement as that is not covered under warranty. Enphase already offered a couple years ago to replace all their early generation product for free - so you can figure how good their reliability promises are....

I do not agree with this opinion. It is a fact that many conventional inverters would not last 25 years but most Enphase microinverters will stay functional for 25 years based on modeled MTBF and components they use. At the same time Enphase no longer pays replacement labor fee, when failed units are replaced. I think it used to be $70 for each replaced unit.

Models starting from M215 have been extremely reliable. I would be more worried about SE power optimizers.

[ajonestx]

Realize that microinverters will not last the 25 years they are warrantied for. The manufacturers do this warranty as a ploy to match the 25 year warranty of the PV panels (which will last 50 years) They will replace the microinverters under warranty but you need to be clear about who is going to do the replacement as that is not covered under warranty. Enphase already offered a couple years ago to replace all their early generation product for free - so you can figure how good their reliability promises are....

do you know how SunPower processes warranty claims?

[nerdralph]

Compared to some places in the U.S, your rates seem cheap especially taking the exchange rate into consideration.
Too bad about the gouge and screw tax - I hear a lot about that from my many Canadian friends who visit me in So. CA in the winter - but take some solace in the idea that your health care is a whole lot cheaper.

Alberta actually has lower sales taxes (5% total) than a lot of US state and local sales taxes. In Nova Scotia I think it's higher than anywhere in the US at 15%. But for solar we don't have the 25% duties on Chinese imports. The US-based Solis rep I spoke to told me the $895(CAD) wholesale price I pay for a 1P6K-4G-US from Guillevin-Greentech is less than their landed import cost from China after the duties are added.

[J.P.M.]

1 US dollar = C$1.24, so C$2 is about US$1.60. I've never quoted more than C$10,000 for a 5kW system installed on a residential roof. Those prices are before any subsidies, and before sales taxes. I primarily install string systems and avoid MLPE as much as possible. I was using Solis inverters, but I may switch to Growatt's new hybrid inverters if my testing on a 6000TL-HX-US goes well.

Solar subsidy programs have changed frequently since they first became available a few years ago. Currently there is $1/W available under the Greener Homes program, to a maximum of C$5000, or 60c/W from the province to a maximum of C$6000. The two subsidies cannot be combined on the same system, but they could be used for two different systems such as on a house and garage.

Local energy costs are close to the highest in Canada at 17c/kWh including GST. Nova Scotia has full net metering, so it is one of the better provinces for PV despite having relatively low insolation (around the same as most of the New England states). A typical system will produce 1100kWh/yr/kWp.

http://solarns.ca/sites/solarns.ca/files/2018-10/NS_Solar_Price_report_2018.pdf

My confusion was that I took the antecedent subject to your "about US 160c/W" from your post as being the amount of subsidy per STC W, not your installed price per/STC W in U.S. D.

Thank you for the other information.
Compared to some places in the U.S, your rates seem cheap especially taking the exchange rate into consideration.
Too bad about the gouge and screw tax - I hear a lot about that from my many Canadian friends who visit me in So. CA in the winter - but take some solace in the idea that your health care is a whole lot cheaper.