So how bad are string inverters vs microinverters?

[nomadh]

I think by parallel, he is saying that if one fails - it doesn't affect the others as opposed to a series string where one failure would affect the whole string. While I go along with that systems analysis in general, my thinking on this issue is that solar is different. Solar PV panels are incredibly reliable and a string of them in series virtually never fails. Even from a shading efficiency viewpoint, string inverters have been proven to be as good as individual optimized arrays except in special situations. Would you rather have a super reliable system with limited visibility into failure modes, or a system with a much higher risk of failures but those failures are easily identified? I'll take the high rel system any day.
I contend that putting electronics in a hostile environment like under a roof mounted array is just asking for trouble...

But thats where this thread took a turn for me. I agreed with you on the simplicity but now I hear the new regs require you to have per panel electronics for shutdown. Maybe still not as complicated as a microinverter but at this point if you must have per panel electronics and the inherent unreliability this would push me towards microinverters and the per panel info I could get from it.

[solarix]

I think by parallel, he is saying that if one fails - it doesn't affect the others as opposed to a series string where one failure would affect the whole string. While I go along with that systems analysis in general, my thinking on this issue is that solar is different. Solar PV panels are incredibly reliable and a string of them in series virtually never fails. Even from a shading efficiency viewpoint, string inverters have been proven to be as good as individual optimized arrays except in special situations. Would you rather have a super reliable system with limited visibility into failure modes, or a system with a much higher risk of failures but those failures are easily identified? I'll take the high rel system any day.
I contend that putting electronics in a hostile environment like under a roof mounted array is just asking for trouble...

[J.P.M.]

I would say microinverters are better because they function in a parallel circuit.

Can you elaborate on the thinking that led you to that opinion ?

[jflorey2]

I would say microinverters are better because they function in a parallel circuit.

In specific cases (radically different insolations/temperatures/panel types) yes. But as has been mentioned in this thread dozens of times now, there are many cases where a string inverter is just plain simpler, cheaper and more reliable.

[SunEagle]

I would say microinverters are better because they function in a parallel circuit.

There are good and bad points when to consider micros or string inverters.
Each person needs to understand what they are getting and how much it costs them. As long as the decision to go with micros is not the seller's hard push because most people don't need the micros and their system will work just fine with a string.

[Mike90250]

I would say microinverters are better because they function in a parallel circuit.

But, that parallel circuit is only @ 240VAC. If there is any appreciable cable distance, you have to use larger gauge wiring to keep the line voltage loss to a minimum.

With a 500VDC string inverter, a lot of the cable loss is done away with. Engineering trade off's everywhere.

[solardreamer]

Again a thanks! I do not know how I overlooked the 7X. Also, I believe I might be better off with the IQ7 Plus because of the Vmp of the 7X is upwards to 53-64 whereas the 7Plus is a closer match to the panels at 27-45. Making progress! I have so many things going I feel the same as one does playing whack-A-mole. Goal remains to have permits around early summer.

IQ7+ is definitely more common so it would be great if it works for you. Good luck with your system.

[Warren93nature]

I would say microinverters are better because they function in a parallel circuit.

[foggysail]

Why wouldn't Enphase iQ7X work?

Again a thanks! I do not know how I overlooked the 7X. Also, I believe I might be better off with the IQ7 Plus because of the Vmp of the 7X is upwards to 53-64 whereas the 7Plus is a closer match to the panels at 27-45. Making progress! I have so many things going I feel the same as one does playing whack-A-mole. Goal remains to have permits around early summer.

[foggysail]

Why wouldn't Enphase iQ7X work?

I thought I looked at all of the Enphase's, overlooked that one. It might work! Don't understand though why it has a limited Vmp range whereas the panel's Vmp is 10 volts lower. I am going to put more effort into this. Thanks--

[solarix]

I use APSmart rapid shutdown devices with our string inverters equipped with Sunspec. Its the best way I know of to comply with the rapid shutdown B.S. I figure these devices are way more reliable than any microinverter or optimizer as they are basically a solid state switch with some simple digital controls that can communicate to the inverter. It just burns me up to have to compromise the inherent reliability of a solar array just because two companies are pushing a code rule as a market strategy for their own benefit.

[solardreamer]

Yes, I did find stuff at Amazon, they looked similar to a regular inverter, expensive and did not appear to have weather protection. Had high hopes for Enphase only to find low Vin limits. More tomorrow, have to give htis a break tonight. Not really dead on the roof yet...... there are other panels, just would need more of them. Thank you, everybody, have to say goodnight

Why wouldn't Enphase iQ7X work?

[foggysail]

Yes, I did find stuff at Amazon, they looked similar to a regular inverter, expensive and did not appear to have weather protection. Had high hopes for Enphase only to find low Vin limits. More tomorrow, have to give htis a break tonight. Not really dead on the roof yet...... there are other panels, just would need more of them. Thank you, everybody, have to say goodnight

[solardreamer]

OK, I agree with all of you, the rapid rule is a bunch of crap, now to move onwards. So I said to Self, go the grid tie micro inverter route and be done. After complying with more fire department crap, this time the 3' pedestrian travel lane. I hoped to use Canadian Solar panels, the 450 W bifacial with a VOC of 49.1V to maximize my solar array's power density and so far..................I CANNOT FIND A grid tie micro inverter that I want to use. I don't know how much latitude experts allow for upper voltage limits, but no way will I stick an inverter into the array that has a 50VDC maximum input when the panels have 49.1 VOC.

Yes... anxious for suggestions and damn it, this could force me to a string inverter.

Thx

Which microinverter models have you looked at so far? I am pretty sure there are ones that support 60V and higher.

[foggysail]

Not sure Mike. I used grid paper (gees.......wish I had AutoCad experience) to see where my panels can fit.The only overhang would be about a foot or so on the gable end which I have plenty of space as it is. Maybe I have to re-examing my layout with lower voltage (wattage) panels. The CAnadian's that I was excited to use come with a weight penalty of 62.6#.