Output range on micro inverter

[MaxThisPower]

For my first PV install I'm looking at buying SolarWorld 350w panels and Enphase IQ7PLUS-72-2-US. The enphase has an input of 235W - 440W and max output of 295W. Since the output of enphase is 55 less than what panels can produce, is the 250w waste of money? Or is it better to buy a 300w panel instead?

[J.P.M.]

1.) See what the annual output of a 300 STC W system and a 350 STC W system. Also check for the annual clipping by running both with a 250 W inverter, which for the 300 STCW panel would mean a DC/AC ratio of 300/250 = 1.20, and for the 350 STC W panel a DC/AC ratio of 350/250 = 1.40.

2.) Decide/estimate how small a system you need by dividing however much annual load you want to offset by the results of step 1 above.

3.) Because of that DC/AC ratio, you'll probably need a bigger (electrical) size array if you use higher wattage panels. The annual difference won't be whole lot, maybe 2-4 %, and maybe you'll make that up on a bit less wiring/labor on fewer the 350 W panels, but that's not necessarily a good way to design. Sort of like boring/stroking an ICE and then slapping a governor on the output.

4.) Besides having fewer things to go wrong, a properly sized string inverter will avoid most/all of the clipping problems that can come with micros.

[ButchDeal]

For my first PV install I'm looking at buying SolarWorld 350w panels and Enphase IQ7PLUS-72-2-US. The enphase has an input of 235W - 440W and max output of 295W. Since the output of enphase is 55 less than what panels can produce, is the 250w waste of money? Or is it better to buy a 300w panel instead?

What do you mean your first install? Most DIY have little need for more than one system.
the IQ7plus has a sustained output of 290w with 295 being peak.
You are likely to have some but modest clipping. The pv modules are rarely going to produce at their STC rating, so dropping to 300w would drop production as well.

[MaxThisPower]

What do you mean your first install? Most DIY have little need for more than one system.
the IQ7plus has a sustained output of 290w with 295 being peak.
You are likely to have some but modest clipping. The pv modules are rarely going to produce at their STC rating, so dropping to 300w would drop production as well.

When I say first install I mean I'm a noob . Sounds like staying with 350w panels is a better idea.

[J.P.M.]

When I say first install I mean I'm a noob . Sounds like staying with 250w panels is a better idea.

That depends on your goal(s). If one of them is the best design for the least amount of hassle and probably a bit more long term cost effectiveness, if you don't have a lot of shade, a string inverter is a better idea yet. Lots more options.

[MaxThisPower]

That depends on your goal(s). If one of them is the best design for the least amount of hassle and probably a bit more long term cost effectiveness, if you don't have a lot of shade, a string inverter is a better idea yet. Lots more options.

I'll have to keep that in mind. The only reason I'm going with micro inverter is that I have a chimney that will cast a shadow on some of the panels through out the day. On my next install I'll have full sun on the roof and I plan on installing the biggest PV system all at once.

[J.P.M.]

I'll have to keep that in mind. The only reason I'm going with micro inverter is that I have a chimney that will cast a shadow on some of the panels through out the day. On my next install I'll have full sun on the roof and I plan on installing the biggest PV system all at once.

Well, if I was a noob, If I had an area that's shaded by much of anything, and my goal was to max. power, I'd be very careful about getting the economic penalties of shading nailed down as best I could before thinking about putting an array in a less than optimal area.

Reality: PV may not be the best economic way to go. In spite of what the media and peddlers would have all of us believe by helping us to infer, not every application or location is automatically as cost effective as a lot of other ways to lower an electric bill.

[ButchDeal]

I'll have to keep that in mind. The only reason I'm going with micro inverter is that I have a chimney that will cast a shadow on some of the panels through out the day. On my next install I'll have full sun on the roof and I plan on installing the biggest PV system all at once.

Well likely you have rapid shutdown to concern yourself with as well.
Have you priced out the costs of the enphase cabling and monitoring hardwate?

you might have a simpler time installing a solaredge system, though you did not mention the size of the array.

[MaxThisPower]

Well likely you have rapid shutdown to concern yourself with as well.
Have you priced out the costs of the enphase cabling and monitoring hardwate?

you might have a simpler time installing a solaredge system, though you did not mention the size of the array.

This is my rough draft. The first install is on the main roof is around 4.2kW using enphase. The red box is the chimney. Later on I'm planning on adding another 3.8kW on the garage roof.

Screen 3.PNG

[ButchDeal]

This is my rough draft. The first install is on the main roof is around 4.2kW using enphase. The red box is the chimney. Later on I'm planning on adding another 3.8kW on the garage roof.

Screen 3.PNG

So you deffinitly do have rapid shutdown to concern yourself with and a lot more shadows than just that chimney (trees, east and west ridges, etc).
you shouldbe doing micros or optimizers. At your final 8kw size you will be saving with solaredge. I would do a solaredge install with SE7600H which is more than capable of running the full 8kw and more. If yiu are thinking of an EV get the EV version. Make sure you follow the setbacks which mean you will need to leave one of the two valies clear and the ridge area.
When you put it in the garage, you should stay to the north end away from the trees and put some on east and west.

[MaxThisPower]

So you deffinitly do have rapid shutdown to concern yourself with and a lot more shadows than just that chimney (trees, east and west ridges, etc).
you shouldbe doing micros or optimizers. At your final 8kw size you will be saving with solaredge. I would do a solaredge install with SE7600H which is more than capable of running the full 8kw and more. If yiu are thinking of an EV get the EV version. Make sure you follow the setbacks which mean you will need to leave one of the two valies clear and the ridge area.
When you put it in the garage, you should stay to the north end away from the trees and put some on east and west.

I'm confused on your message. Should I or shouldn't I go with micros? If I go with solaredge then I would have to use optimizers, right?

[ButchDeal]

I'm confused on your message. Should I or shouldn't I go with micros? If I go with solaredge then I would have to use optimizers, right?

You should not go with a string inverter.
You should go with either micros or solaredge.
i would recomend solaredge over micros as a personal and professional recomendation though.

[jflorey2]

This is my rough draft. The first install is on the main roof is around 4.2kW using enphase. The red box is the chimney. Later on I'm planning on adding another 3.8kW on the garage roof.

Optimizers or microinverters on the 4.2kW, string inverter for the 3.8kW. If you can move the array away from the chimney, then a string solution might work there.

[ButchDeal]

string inverter for the 3.8kW. If you can move the array away from the chimney, then a string solution might work there.

This would be a mistake, both in that there would be multiple systems as well as multiple shadows from the other roof ridges, stand pipe, and trees as well as the chimney.

[foo1bar]

I installed the system on my house.
I used Solaredge due to shading and 3 different orientations of panels.
One of the threads from my install is "DIY system in CA; 8.68kw system"