DIY Solar PV Installation

It peaked at 1.98 kW on the first day, so I was getting super close to the max of 8 x 250W and I'd expect the summer months to get there more often. But you're totally right; if I go with cheaper 250W panels, M215s are the way to go. Are there any other differences between the two?

I took a peek at your system and it obviously looks amazing! If I go the DIY route, should I ask my last installer to give me access to Enlighten Manager ($249 for activation?) now or later or just go directly to Enphase when it's time? How's that handled when I want to add microinverters and modify arrays myself?

cracovian said:

I did peak at 1.98 kW on the first day, so I was getting super close to the max of 8 x 250W and I'd expect the summer months to get there more often.

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With the very rare exception due to edge-of-cloud effects, you will never hit the peak in the summertime. This is because the PV modules produce less power when they are hot. Also, if your array faces South, the sun never enters the boresight in the summertime. Instead, it goes straight overhead around here. Where you live, it may even go closer to the boresight for your NORTH-facing roof in the middle of the summer. Likely you would saturate most often in the spring when it is coldest and the sun is closest to the boresight. The sun is near the boresight also in the fall, but it is typically not as cold.

cracovian said:

But you're totally right; if I go with cheaper 250W panels, M215s are the way to go.

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Personally, I wouldn't lower the module power rating. More is better unless you are paying a fortune per watt.

cracovian said:

Are there any other differences between the two?

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No.

cracovian said:

I took a peak at your system and it obviously looks amazing! If I go the DIY route, should I ask my last installer to give me access to Enlighten Manager ($249 for activation?) now or later or just go directly to Enphase when it's time?

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It seems they have changed some things. In the past, access to Enlighten Manager was included with the purchase of an Envoy. And now they have something coming called MyEnlighten. I guess they're trying to make more money to try to pay for the replacements for my M190s which are failing.

cracovian said:

How's that handled when I want to add microinverters and modify arrays myself?

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Based on advice given here by Weatherman, I just asked Enphase for access to Array Builder and they gave it to me. Later I discovered that they have a FAQ for that saying you just needed to ask, but now I do not see it. This one is close.

Here is some of their training to show what Array Builder looks like: Array Builder Training videos

cracovian said:

It peaked at 1.98 kW on the first day, so I was getting super close to the max of 8 x 250W and I'd expect the summer months to get there more often.

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Just a quick follow-up on this. Based on your production record to date, you would have lost a total of 43Wh of production since installation had you installed M215s, versus 53.5 kWh of total production, or 0.8%. That is during a particularly cold November, which is one of only about five months of the year when this can happen outside of weird weather events.

As such, I'll stand my my assertion that you would lose less then 0.5% of total production by going with M225s.

It would be pretty easy to test: Simply swap one of your M250s for a friend's M215. I'm sure they wouldn't mind!

In fact, my daughter lives in GA. I'll send one down with her after Thanksgiving and she can bring the M250 back at Christmastime. It would be an easy way to see if you can save on your next upgrade.

A correction: I was a bit wrong-minded with a couple of my previous statements:

RegGuheert said:

- Your roof pitch is similar to mine, but you live in a climate that is 5% lower in latitude, so the sun is higher in the sky during all parts of the year, so the sun will be farther from the boresight of your array during the coldest months.

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RegGuheert said:

That is during a particularly cold November, which is one of only about five months of the year when this can happen outside of weird weather events.

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The very first part about the sun always being higher in the sky is correct. But that means that the sun will be CLOSER to your boresight at the winter solstice than it is here. (Here, the sun is a bit below the boresight during all of December and January and goes directly through it at the beginning of April.) So that means that you are only likely to get to the highest power levels from about November through February.

In any case, we should be able to assess the TOTAL amount of annual loss due to lower-power inverters at your site by about the middle of March. From March through October, I do not expect to see your system go above 1800W except extremely rarely.

It's fascinating stuff about the sun. I really expected my summer current and total production to be off the charts and here you are blowing my bubble :-( What's next, you're going to tell me that it's the Earth revolving around the sun and not the other way around?

[Edited out for confusing current and total production]

I'll measure my tilt tomorrow - I'd love for you to comment on what it means depending on the seasons. To me it looks like an excellent tilt!

I do get your point about the inverters and thirty bucks is thirty bucks. But then you also told me not to go with lower-rated panels. That would mean a difference between $185 250 Watt Suntechs vs. $336 280 Watt LGs for example... It seems (falsely?) like a bigger waste of money though those LGs sure look purty

I found your ladder lift interesting.
I thought about that, but my panels are 40" wide, and was worried about them sliding off.
Nice work.

I used the new M250's with internal ground.

I have only one more panel to get up, and I'm waiting a couple days till the temperature gets back above freezing :roll:

I found the Enlighten manager and array builder really easy to use.

I'll post it when I'm finished.

cracovian said:

It's fascinating stuff about the sun. I really expected my summer current and total production to be off the charts and here you are blowing my bubble :-( What's next, you're going to tell me that it's the Earth revolving around the sun and not the other way around?

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:lol: Your ENERGY production will absolutely be maximum during the summertime. But that is due to the long days with the sun almost directly overhead. But your instantaneous POWER production, which is what an inverter might limit, is the LOWEST during the summertime for two reasons: high PV module temperatures and the sun never passing through (or even particularly close to) the boresight of the array. The entire discussion revolved around whether or not you could get away with lower-power inverters in your application to save some money without hurting yearly ENERGY production.

cracovian said:

I'll measure my tilt tomorrow - I'd love for you to comment on what it means depending on the seasons. To me it looks like an excellent tilt!

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I think the tilt of your roof is very nearly optimum for solar production, assuming the roof is anywhere close to pointing South. My favorite site for determining optimum tilt for a given location is Solmetric. If your roof is really 7/12 pitch, that is 30.3 degrees elevation. If the azimuth of your roof is between 165 and 200 degrees, then you are within 1% of the production you would achieve with optimal pointing!

cracovian said:

I do get your point about the inverters and thirty bucks is thirty bucks. But then you also told me not to go with lower-rated panels. That would mean a difference between $185 250 Watt Suntechs vs. $336 280 Watt LGs for example... It seems (falsely?) like a bigger waste of money though those LGs sure look purty

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Wow! :shock: I hadn't looked at prices and I did not realize that moving from 250Wp to 280Wp changed the price per from $0.74/watt to $1.20/watt. But that is why I included the caviat: "More is better unless you are paying a fortune per watt." I would agree increasing your $/watt by 64% qualifies as a fortune! That is clearly one reason your system was expensive. So, yeah, if you can save a lot by going with smaller PV modules, then definitely reduce the microinverter to the M215 at the same time. But note that energy production changes proportionally with the PV module rating, so a 250Wp panel will only harvest 89% as much electricity as a 280Wp panel. By contrast, with microinverters going with the larger power rating has almost no effect on energy harvest.

To that point, please note that over the past three days, November 20 through 22, even though you have had completely sunny weather and no clouds, the M250 microinverter has resulted in zero additional energy harvest versus what would have been produced with M215s. You can see this by noting that not a single one of the 15-minute production periods in the "Hourly" plot on your site exceeded 450Wh during those three days.