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-   -   DIY solar array 12.5 kw (https://ecorenovator.org/forum/showthread.php?t=3053)

pinballlooking 05-03-15 03:24 PM

1 Attachment(s)
I am happy with my Canadian Solar panels they are a good price and perform very well.
There are a lot of good panels out there California does independent testing.

Incentive Eligible Photovoltaic Modules in Compliance with SB1 Guidelines - Go Solar California
I would make sure they are on the list and did well.

Most 60 cell panels work with Enphase.


Make sure you center tap your 17 string.

With the M215-60-2LL-S22-IG, S23-IG, or S24-IG, the DC circuit within the M215 is isolated and insulated from ground


Mark sure you get one of these to carry the panels on the roof.
Grip 4-Head Suction Cup Dent Puller | Auto Body Tools| Northern Tool + Equipment
These stick so well to the glass and one person can carry the panel under your arm very easy.

http://ecorenovator.org/forum/attach...1&d=1430684671


Racking I only have experience with two types so I am not the one to tell you what one this the best to use.

Get the racking from who you order your panels from. It have to be truck shipped and the shipping will be so much cheaper if it is shipped with your panels.
I used unirac U-builder to help know what components I needed to order.
It was very helpful.
http://unirac.com/residential/reside...nt-residential
• then click
• Configure Project

MN Renovator 05-04-15 09:13 AM

1 Attachment(s)
Quote:

Originally Posted by stevehull (Post 44878)
What is the model designation of the M 215 that does not need the external ground?

I am getting real close to buying and am thinking of getting the 280 watt panels that are a LOT cheaper than the 300 watt panels. The M 215 should be a very good match and if I get a few minutes of clipping, then I am not wasting much.

Will do 17 panels per string to minimize those costs. I have two large barn roofs, both within 15 degrees of south, that I can use. Probably start on the barn out of sight from the street so the county appraiser won't gig me . . .

Will do 34 panels for now (two rows) and that will be about 9 kW or so. Am on the Revnu lists so waiting for a good catch there (as you recommended)!

Any advice on the different brands of racking?

Steve

In this example 4/22/2015 12pm-3pm produced 8.64kwh, if clipped at 225wh would have produced 8.1kwh. I would have lost about 2.5% of the day's output on April 22nd with 540wh on the 'clip table'.

My system is 12 280 watt modules with a Solaredge inverter and individual MPPT with SolarEdge optimizers. I've seen my inverter produce 3395 watts before clipping, granted that is rare for me since my inverter isn't undersized for my system and most high production days peak around 3000 watts. I'm not pointed directly south though, this is a southwest azimuth otherwise my peak would be higher and earlier in the day. I'm also in Minnesota where we have less solar resource at our latitude.

You might want to price out a SolarEdge system for what you are doing, especially with such a large system. This will let you you get the electrolytic capacitors off the roof and out of the heat of the sun along with saving money while clipping less and still getting individual module MPPT.

The SE10000A-US is rated for 10950 watts max output and allow you some room for expansion.
You can use multiple strings of 8-25 modules with 5250 max power per string and you can have different lengths to each string.

pinballlooking 05-04-15 09:34 AM

I think Solaredge is a good solution “Robaroni” on here also has this installed.
They seem to perform well and it I went with a couple string inverters that is the way I would have gone.

A system your size would have 1or 2 inverters and at the time I was looking into it these units were not warranty as long as the rest of the system. (and still are not the inverter is 12 years not 25 years like Enphase) Comparing cost over time include inverter replacement cost or extended warranty to 25 years. The optimizer on the roof was warranty for a long time just not the inverter.

The monitoring setup is top notch. The wiring between panels in cheaper.
It you have an inverter go bad you lose ½ your system until you can get it fixed.

I did not want that one or two points of failure. Buy if this did happen you could just buy an inverter and have the other one fixed you would have a spare.
One of the reasons I like both of these solutions is you get per panel monitoring and that was a must have for me. That way I can easily monitor everything and tell if a panel loses a diode or a micro inverter goes bad.

A plain string inverter was cheaper for me buy I did cost over time and replacing the inverters the cost was almost a wash. You don’t get tax credits on system repairs only installs. I was getting 55% tax credits.

pinballlooking 05-07-15 10:14 PM

1 Attachment(s)
I love this time of year in May we have made 511 KWh so far a nice 7 days.
Hopefully the sun is shining your arrays also.

http://ecorenovator.org/forum/attach...1&d=1431054881

stevehull 05-08-15 07:36 AM

Pinball, your post on inverters (a couple post ago) described exactly why I am looking at microinverters and Enphase in particular.

One important issue not discussed is that the length of DC cable run is VERY short, just a couple feet. With a typical string inverter, you loose a lot of power (IR loss) in the cables that run off the roof to the single string inverter below. Large copper cable, to minimize these IR losses, is very expensive. I would far better use 240 V at low amps in a cable compared to DC runs at high current.

The issue of reliability cannot be overstated. You are exactly correct that the tax credits/deductions are there for new install and do not cover future losses. Enphase does offer 25 year warranties and I know of people that are given new M215s to replace the old 190s that have died.

At the age of 62, I am increasingly looking at low maintenance options as my mantra. Years ago, I could do short term fixes as I would have time/energy. At least I thought I did . . .

But now, I am very less inclined to do something that is half thought through - hence my almost year long examination of what to do. I also have the cash available this fall and it was not available a year ago.

Still think it is a reasonable experiment to do an input - output test of an M215 as I did not see clear clipping on your video grab. It looks like there is a plateau about 225 watts, but hard to tell.

Lastly, I truly appreciate your, and others, words of encouragement. As someone suggested in a private message, I did calculate an internal rate of return for my PV costs, current kWhr rate and expected likely future increases in that rate (I used 1% > inflation). It came out to 22.5%! This was based on a self install - something that I can still do.

This RoR is due to the fact that a PV system is like an annuity - but one that becomes increasingly valuable over time as kWhr rates increase. It sure amazed my CPA as he double checked my numbers (inputs from PVwatts, people here, estimates of PV system costs, etc).

Lastly, I can't control my future taxes, home/farm insurance and those are ever increasing. But I certainly CAN control what I pay for energy. Minimizing infiltration, good insulation, minimizing roof heat conduction, good windows, geothermal heat pumps, solar hot water heater, efficient lighting (CFL, LED) have all been done. Now time to look at PV systems and a car with a battery . . . .

Thanks,

Steve

pinballlooking 05-08-15 08:09 AM

Yes the graph topped out at 225watts you will not see defined clipping on my system. My solar modules are only 230 watts and 240 watts. These are not big enough to see defined clipping and bigger modules are better with M215’s.

The 230-240 watt were being closed out when I bought my system I was trying to keep cost per installed watt down. It is funny all the sales guys kept telling me the M215 topped out at 215 watts. They really don’t know they just want to make money. At least the ones I talked to.

When I was system shopping I kept a spread sheet that I put in PVwatt and cost info it would tell me exactly my payback time for each option. But I make sure I compared apples to apples if something had a lower warranty I got the cost to upgrade it.

I also see where string inverters need replaced and even under warranty the can take weeks to get fixed. I did not want to have my array down for weeks. I even have a spare M215 setting here just in case one goes bad I will put this one in and send the other one to Enphase for replacement. It is cost effective to have a spare.

It was a must for module level monitoring. This just makes it so easy for me to know what to fix it if there is ever an issue. Converting to 240 volts quickly it very convent a lot of use are very comfortable with standard wiring.

My system is paying itself off sooner than all my estimates. Our power cost increases every year 7-10 % they have been doing that for years now. I don’t see that stopping anytime soon. So my solar array will be getting better returns than my 401K.

I don’t like maintenance either and when a system last 25-30 years we all need to think about it. I am trying to put things in now so some day when I retire my cost of living will be low so I can enjoy my time.

Good luck on whatever you decide just remember the Fed tax credit expires this year and the system has to be inspected and operational before Dec 31 of 2016 to get the tax credit. They could extend it but you never know.

stevehull 05-08-15 08:54 AM

Pinnball, you wrote that "The M250 can have 16 modules on a branch circuit and that goes to a 20 amp breaker."

However, reading the Enphase material they state that only 14 M250 modules should be on a 20A string (17 for M215s).

Comments?


Steve

pinballlooking 05-08-15 09:05 AM

1 Attachment(s)
Yes they are 16 per string. If you look at 230 Volt it will be 14 per string
Microinverters - Enphase Energy
http://ecorenovator.org/forum/attach...1&d=1431095506

http://enphase.com/global/files/M250_DS_EN_60Hz.pdf

Robaroni 05-08-15 09:24 AM

Quote:

Originally Posted by pinballlooking (Post 44892)
I think Solaredge is a good solution “Robaroni” on here also has this installed.
They seem to perform well and it I went with a couple string inverters that is the way I would have gone.

A system your size would have 1or 2 inverters and at the time I was looking into it these units were not warranty as long as the rest of the system. (and still are not the inverter is 12 years not 25 years like Enphase) Comparing cost over time include inverter replacement cost or extended warranty to 25 years. The optimizer on the roof was warranty for a long time just not the inverter.

The monitoring setup is top notch. The wiring between panels in cheaper.
It you have an inverter go bad you lose ½ your system until you can get it fixed.

I did not want that one or two points of failure. Buy if this did happen you could just buy an inverter and have the other one fixed you would have a spare.
One of the reasons I like both of these solutions is you get per panel monitoring and that was a must have for me. That way I can easily monitor everything and tell if a panel loses a diode or a micro inverter goes bad.

A plain string inverter was cheaper for me buy I did cost over time and replacing the inverters the cost was almost a wash. You don’t get tax credits on system repairs only installs. I was getting 55% tax credits.

Steve,
DC and AC both follow about the same characteristics at low frequencies so it's not the run of DC so much. my Solaredge intertie micro-inverters are DC going into an accumulator panel that turns the 375 or so string volts into AC for the grid. They have the same efficiency as AC would, not that Enphase is a bad option but my efficiency is just about the same. Either way micro-inverters are the best path to take in my view.

My off grid/intertie system runs at 48 and 72 volts for the two legs so I have to run each one into an MPPT before the Outback inverters. It's a little more of a pain and the run wires are fatter.

Rob

stevehull 05-09-15 04:37 PM

Pinball,

The 30% renewable energy tax credit expires on Dec 31 of 2016, not January 1, 2016. You are correct, that it must be fully permitted and in operation by the expiration date.


Steve


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