New 4.8KW installation in San Diego just finished

[thethingx]

A lot of times, it's a personal preference. For me, I really liked to have per-panel monitoring. But I don't like the idea of having the most venerable part of your system (the inverter) up on the roof constantly under extreme heat/cold/humidity/wind etc.. Also the horrendous reputation of m190 doesn't make me feel good about Enphase either, even though the newer generations of m215 and m250 seems to have vastly improved. SMA (or other reputable string inverters) is a solid choice and probably will give you the best overall value if you don't have shading issues. Another observation which might give some performance edge to panels that're individually tracked (eg. Enphase and SolarEdge) is that there're always some variation between panels, eg temperature difference, dirt/leaf/bird poop covering, degree of degradation etc. For example, I always find my panels on the outside performance better slightly (cooler temperature?), see below.
[ATTACH=CONFIG]6395[/ATTACH]

If you go to San Diego team's pvoutput.org page (http://pvoutput.org/listteam.jsp?tid=859), pick a sunny day and rank based on efficiency, Enphase and SolarEdge are consistently on the top.

That's good info, thanks for the reply

[J.P.M.]

That's good info, thanks for the reply

I'd suggest the greater efficiency on a daily basis for micro equipped systems is to be expected as many, if not most arrays, micros and string either one, for the most part are subject to some form of shading over the course of a day. That's were the characteristics of micros/optimisers have an advantage. I'm pretty clear and shade free and still get ~ 1% - 4%/day output penalty in the late afternoon depending on the season. If micros/optimisers for a 327 had been available when I bought the system, there probably would be a slight advantage, reducing that loss by probably about half or so +/- some, but not eliminating it entirely.

Warranty labor questions aside, the disadvantages, which may have more long term implications, involve the greater # of failure points and system configuration to get at a problem in the middle of what are usually tightly packed arrays.

While not having looked at the data you cite, I'd suspect I'd see the advantage of increased output for micros to exist as you say, but that it may be relatively slight, with the importance of such additional output modified further by the tendency of folks to oversize arrays. To the extent an array is oversized, any extra output from micros is mostly moot, and we're back to the increased probability of problems due to the increased # of failure points as one consideration of many, maybe larger for some users than others.

The idea that micro equipped systems may, on average, be newer as a whole than string systems and therefore have less panel time dependent degradation looses may also be a contributory factor, but quite honestly, based on the relatively short amount of time most all systems have been operational, and also from what I measure around here, I'd suspect that's not as big factor as published panel degradation #'s would indicate.

Still, pay your money, take your choice. Just walk in with open eyes and mind, and know what the consequences of the choices.

[thethingx]

I'd suggest the greater efficiency on a daily basis for micro equipped systems is to be expected as many, if not most arrays, micros and string either one, for the most part are subject to some form of shading over the course of a day. That's were the characteristics of micros/optimisers have an advantage. I'm pretty clear and shade free and still get ~ 1% - 4%/day output penalty in the late afternoon depending on the season. If micros/optimisers for a 327 had been available when I bought the system, there probably would be a slight advantage, reducing that loss by probably about half or so +/- some, but not eliminating it entirely.

Warranty labor questions aside, the disadvantages, which may have more long term implications, involve the greater # of failure points and system configuration to get at a problem in the middle of what are usually tightly packed arrays.

While not having looked at the data you cite, I'd suspect I'd see the advantage of increased output for micros to exist as you say, but that it may be relatively slight, with the importance of such additional output modified further by the tendency of folks to oversize arrays. To the extent an array is oversized, any extra output from micros is mostly moot, and we're back to the increased probability of problems due to the increased # of failure points as one consideration of many, maybe larger for some users than others.

The idea that micro equipped systems may, on average, be newer as a whole than string systems and therefore have less panel time dependent degradation looses may also be a contributory factor, but quite honestly, based on the relatively short amount of time most all systems have been operational, and also from what I measure around here, I'd suspect that's not as big factor as published panel degradation #'s would indicate.

Still, pay your money, take your choice. Just walk in with open eyes and mind, and know what the consequences of the choices.

If you had to make a choice today, what would you go with?

[J.P.M.]

If you had to make a choice today, what would you go with?

String in a hot NY second. Simpler, easier to service, lower probability for problems making for, in my engineering judgment, a better, more reliable system, easier to maintain and spot problems. The extra monitoring capabilities and the potential for a slightly greater output are not worth the drawbacks/shortcoming to me.

Also, for those who like to see output and claim problems are easier to spot: True. But, I'd bet the novelty soon wears off and, given all the other variables that affect system output, a 5-10% drop in output from 1 bad micro will probably get noticed less than if/when a string inverter craps the bed and the monthly bill takes a big jump.

[thethingx]

String in a hot NY second. Simpler, easier to service, lower probability for problems making for, in my engineering judgment, a better, more reliable system, easier to maintain and spot problems. The extra monitoring capabilities and the potential for a slightly greater output are not worth the drawbacks/shortcoming to me.

Also, for those who like to see output and claim problems are easier to spot: True. But, I'd bet the novelty soon wears off and, given all the other variables that affect system output, a 5-10% drop in output from 1 bad micro will probably get noticed less than if/when a string inverter craps the bed and the monthly bill takes a big jump.

I wonder what the fail rate is for these things are. With the warranty, you aren't taking much of a risk.

[thejq]

I wonder what the fail rate is for these things are. With the warranty, you aren't taking much of a risk.

FWIW, I've yet to learn any confirmed failure with SolarEdge optimizers due to defect.

[J.P.M.]

I wonder what the fail rate is for these things are. With the warranty, you aren't taking much of a risk.

Failure rates are probably pretty/very low at this time, partly because they are somewhat new, and while becoming more common, not yet ubiquitous.

Read the warranty carefully, particularly with respect to who pays labor. With multiple failure points, the PROBABILITY of a failure increases. How many failures in the middle of an array that requires removal/reinstall of multiple panels are acceptable ? What does that removal/reinstall do to the integrity of the wiring/fixing/etc. of the affected panels and thus the rest of the array ? IMO, too many uncertainties and things to go wrong for the possibility and amount of potential increased output, but opinion vary.

[J.P.M.]

FWIW, I've yet to learn any confirmed failure with SolarEdge optimizers due to defect.

Me too, and maybe (we all hope) robust design and good Q.C. will bear fruit. But, its early.

[karlf]

LG is definitely a brand you can trust and bank on. Personally I think it deserves the premium of $0.2-0.3/W. Plus I think LG is the only solar manufacture in the world that can claim "carbon free", whatever it implies, it must be good for the environment. I'm with you on not trusting micros, but I'm a geek and I like to see per-panel performance, so I picked SolarEdge which is probably the lesser of the two evil. I'm not sure if running AC 24/7 is a efficient way to "burn" through the SDGE credits. Maybe EV is better a way?

BTW, I think you meant 4MWh (not 4GW).

Yeah mega.

As for AC it was a joke. We will certainly have a surplus and we assumed the kids will use more power as they get older. Eventually we will end up with an EV. Right now there's not an EV made I would consider as a personal car. The i3 is fun to drive but the range/interior size/materials turn me off and the Tesla is too big for what we need. Eventually I'm sure BMW will make a decently ranged EV (200+ miles) that doesn't use questionable interior materials and has space for 4 people like our current car. Seeing the spread of CF to the next gen 7 series has me hopeful CF will find its way to the 3 eventually and then we'll hopefully see more plug-inabilities matched to light weight.

[s_man]

I apologize for being unclear and assuming the vendor was handling all your paperwork.

Similar to you, I expected and made clear to all bidders on my project that they would be held to the same standards I held my depts. to when I was working. I also made sure all bidders understood my R.F.P. particulars before responding and during negotiation(s), including follow through and payment expectations and conditions. Two items in particular which were part of my R.F.P. and later became part of my contract : The successful vendor didn't get paid until system turn on, and, if they missed the completion date, they paid my electric bill until they completed work as a contract deduct. All bidders advertised and stated verbally to me a priori that they handled all paperwork, so I held them to their word. The project completed 8 days shy of schedule (10/03/13). The county inspec. showed up the following week Fri. (10/11/13). I did call SDG & E the following Tues. after inspec. to check paperwork progress/pass through between the county and SDG & E, and to ensure the vendor was following up. Coincidentally perhaps, my approval letter showed up 2 business days later, 10/17/13. I ceremonially fired up the system at solar noon that day, the proj. eng.. initiated the monitor the next day, and the salesperson showed up 10/21/13 and walked away w/ a check.

Hi J.P.M,
It's seems you got the contract very well specified on the terms and schedule. If you don't mind could you share the terms you put down. According to my contractor's terms ( I am about to sign next week ), seems I have to pay 1st major part at rack installation and almost full at the time they install the inverter and before city signed off, the last $500 due at city signed off. Does it sound right to you? Thanks

[gvl]

Hi J.P.M,
It's seems you got the contract very well specified on the terms and schedule. If you don't mind could you share the terms you put down. According to my contractor's terms ( I am about to sign next week ), seems I have to pay 1st major part at rack installation and almost full at the time they install the inverter and before city signed off, the last $500 due at city signed off. Does it sound right to you? Thanks

Just an fyi, my payments are as follows:

$1,000 is due upon signing of the contract
$$,$$$ is due after city signoff
$1,000 is due after PTO is granted

[s_man]

Just an fyi, my payments are as follows:

$1,000 is due upon signing of the contract
$$,$$$ is due after city signoff
$1,000 is due after PTO is granted

Thanks gvl! I think yours is more reasonable.

[J.P.M.]

Hi J.P.M,
It's seems you got the contract very well specified on the terms and schedule. If you don't mind could you share the terms you put down. According to my contractor's terms ( I am about to sign next week ), seems I have to pay 1st major part at rack installation and almost full at the time they install the inverter and before city signed off, the last $500 due at city signed off. Does it sound right to you? Thanks

The particulars for sizing, locations and equipment had already been specified in the R.F.P.

I left dates, payment schedule and commission date open as negotiating points at R.F.P., but all vendors also knew of my penalty clause if they missed their date at R.F.P. They also knew they were in a competitive bidding situation and that while low bid was important, quality was more important. The job was also spec'd pretty tight material wise, but with requests for 2 different panels and 2 slightly different array sizes for each mfg.

After I got bids back, I negotiated the payment terms to $1K down at contract signing and balance at commissioning - basically county signoff - not PTO from SDG & E - as the vendor has little control over that. However, that $1K down seemed to be OK with all bidders. I was amenable to progress payments. the bidders wanted none.

One reason I may have had luck on the bidding was I only requested quotes from established electrical contractors who had been in business for some time and were therefore, perhaps familiar with the bidding process. I treated it like a professional transaction and perhaps that helped them do the same.

[s_man]

The particulars for sizing, locations and equipment had already been specified in the R.F.P.

I left dates, payment schedule and commission date open as negotiating points at R.F.P., but all vendors also knew of my penalty clause if they missed their date at R.F.P. They also knew they were in a competitive bidding situation and that while low bid was important, quality was more important. The job was also spec'd pretty tight material wise, but with requests for 2 different panels and 2 slightly different array sizes for each mfg.

After I got bids back, I negotiated the payment terms to $1K down at contract signing and balance at commissioning - basically county signoff - not PTO from SDG & E - as the vendor has little control over that. However, that $1K down seemed to be OK with all bidders. I was amenable to progress payments. the bidders wanted none.

One reason I may have had luck on the bidding was I only requested quotes from established electrical contractors who had been in business for some time and were therefore, perhaps familiar with the bidding process. I treated it like a professional transaction and perhaps that helped them do the same.

Thanks JPM! You're good at negotiating, I couldn't imagine myself do what you did. I usually feel like I am asking for too much or being too picky and may offend the contractor. How do you get them to agree to terms and clause of penalties without intimidating them? And do you negotiate before the contract signing date and have them already put in their contract or do you do it on the date and just write it down right there? Thanks for your input!

[jd31]

The particulars for sizing, locations and equipment had already been specified in the R.F.P.

I left dates, payment schedule and commission date open as negotiating points at R.F.P., but all vendors also knew of my penalty clause if they missed their date at R.F.P. They also knew they were in a competitive bidding situation and that while low bid was important, quality was more important. The job was also spec'd pretty tight material wise, but with requests for 2 different panels and 2 slightly different array sizes for each mfg.

After I got bids back, I negotiated the payment terms to $1K down at contract signing and balance at commissioning - basically county signoff - not PTO from SDG & E - as the vendor has little control over that. However, that $1K down seemed to be OK with all bidders. I was amenable to progress payments. the bidders wanted none.

One reason I may have had luck on the bidding was I only requested quotes from established electrical contractors who had been in business for some time and were therefore, perhaps familiar with the bidding process. I treated it like a professional transaction and perhaps that helped them do the same.

As a procurement professional, I have discerning taste when it comes to sourcing diligence. I put my installer through the wringer too but not to the same extent as you. Nice work!