Help with new system shopping

[desant89]

All, I'm not that well versed with some if this so please excuse some newbie questions. Basically, I have a pretty flat roof in the back of my home that gets sun all day. It a perfect scenario. No shading at all. Well that is the only place I want to put panels.

I have a hot tub, a pool etc. And use a lot of power. Probably like 16k+. The design so far has 34 LG 360 panels. The debate is whether to use solar edge or Enphase. To me, after researching all over, and reading a ton here, it seems like the enphase just won't handle the 360 watt panels, and would clip, leaving too much on the Table. My price so far with the emphase is 3.35/watt, with solar edge, it's 1000. 00 cheaper (different installer). Not sure which he's using, if it's the 11k solar edge, would that be leaving some on the Table also? I live in NJ by the way.

I just want to get the most out of my roof. I already know I will not get 100% of my power from solar, but want to get all I can from it. Putting panels on the front of my roof is not an option. Thanks in advance!

[J.P.M.]

1.) Have you run PVWatts yet ? If not, do so with 10% system loss parameter. What's your zip ? If the 16k = 16,000 kWh/yr., you could probably use an energy audit and some conservation measures would probably be very cost effective before solar, but it's not a disaster. Just don't forget to downsize the array to account for the use reduction.
2.) With no shade, why are you not using a string inverter ?
3.) A 100 % offset of a bill may not be your most cost effective option anyway. It certainly is not a mandate.
4.) Tilting the panels off horizontal will keep them cleaner and boost annual output. You will learn to appreciate that after a year or two of operation. With tilting, you will fit fewer panels on a flat roof to avoid shading adjacent panels, but the greater output from the tilting will tend to offset the fewer # of panels. The net effect is to have fewer panels that are tilted but produce more than a horizontal array. Tilting will cost a bit more but overall you will probably get equal or slightly more annual output for what's probably about equal 1st cost. Horizontal array performance tends to suffer as they get and, more importantly tend to stay dirtier than tilted panels. Another bennie with a tilted array: you can probably get to all the panels more easily for cleaning/service. Think long term.
5.) Download and read "Solar Power Your Home for Dummies". Free, but slightly dated on the net, or ~ $ 25 for an updated hard copy in stores/Amazon, etc.
6.) You may get a better price using panels that are equal quality and mfg., but not necessarily whiz-bang new.

Welcome to the neighborhood.

[desant89]

1.) Have you run PVWatts yet ? If not, do so with 10% system loss parameter. What's your zip ? If the 16k = 16,000 kWh/yr., you could probably use an energy audit and some conservation measures would probably be very cost effective before solar, but it's not a disaster. Just don't forget to downsize the array to account for the use reduction.
2.) With no shade, why are you not using a string inverter ?
3.) A 100 % offset of a bill may not be your most cost effective option anyway. It certainly is not a mandate.
4.) Tilting the panels off horizontal will keep them cleaner and boost annual output. You will learn to appreciate that after a year or two of operation. With tilting, you will fit fewer panels on a flat roof to avoid shading adjacent panels, but the greater output from the tilting will tend to offset the fewer # of panels. The net effect is to have fewer panels that are tilted but produce more than a horizontal array. Tilting will cost a bit more but overall you will probably get equal or slightly more annual output for what's probably about equal 1st cost. Horizontal array performance tends to suffer as they get and, more importantly tend to stay dirtier than tilted panels. Another bennie with a tilted array: you can probably get to all the panels more easily for cleaning/service. Think long term.
5.) Download and read "Solar Power Your Home for Dummies". Free, but slightly dated on the net, or ~ $ 25 for an updated hard copy in stores/Amazon, etc.
6.) You may get a better price using panels that are equal quality and mfg., but not necessarily whiz-bang new.

Welcome to the neighborhood.

Ok, I went to the Calculator. I put in 12.2 for system size, 10% loss with my zip of 08094. Came to 16,634. My actual usage over the last 12 months was like 14200. However, I just added a pool, and a hot tub. Just with the hot tub alone, my usage from Feb to march went from 680 to over 1200. I am sure there are other variables, but I can easily see it will be much more now. I will definitely make changes in my home to save energy, but right now, my bill is way off, and will certainly be much higher. For now I need to keep my usage up to ensure that the power company will allow me to max out the back of my roof. That is why I wanted larger (wattage) panels. Thank you so much for your response so far!

[J.P.M.]

Ok, I went to the Calculator. I put in 12.2 for system size, 10% loss with my zip of 08094. Came to 16,634. My actual usage over the last 12 months was like 14200. However, I just added a pool, and a hot tub. Just with the hot tub alone, my usage from Feb to march went from 680 to over 1200. I am sure there are other variables, but I can easily see it will be much more now. I will definitely make changes in my home to save energy, but right now, my bill is way off, and will certainly be much higher. For now I need to keep my usage up to ensure that the power company will allow me to max out the back of my roof. That is why I wanted larger (wattage) panels. Thank you so much for your response so far!

You're welcome.

I definitely do NOT recommend it, but if you want to maximize an AREA's output (such as your roof) and don't care about what it costs, get Sunpower panels. They will produce about 15-20 % more output per m^2 of panel. You will pay ~ 20-25 % more per installed Watt for such a system. However, the per installed kW output of most any system, Sunpower or anyone else's will, in all likelihood, be the same, whether the panels are SP, or anyone else's.

I just ran your 12.2 kW system using McGuire AFB data and got 13,800 kWh/yr. for std. roof mount, 10% system losses, horizontal orientation. a 40 deg. south facing tilt will get you ~ 16,200 kWh/yr., but that'll cut down on the number of panels you'll be able to use on a flat roof without self shading. What tilt and azimuth will the panels have ?

[desant89]

You're welcome.

I definitely do NOT recommend it, but if you want to maximize an AREA's output (such as your roof) and don't care about what it costs, get Sunpower panels. They will produce about 15-20 % more output per m^2 of panel. You will pay ~ 20-25 % more per installed Watt for such a system. However, the per installed kW output of most any system, Sunpower or anyone else's will, in all likelihood, be the same, whether the panels are SP, or anyone else's.

I just ran your 12.2 kW system using McGuire AFB data and got 13,800 kWh/yr. for std. roof mount, 10% system losses, horizontal orientation. a 40 deg. south facing tilt will get you ~ 16,200 kWh/yr., but that'll cut down on the number of panels you'll be able to use on a flat roof without self shading. What tilt and azimuth will the panels have ?

Honestly, at this point I am not sure. I just obtained some quotes, but none of them mention the tilt. I can tell you that my roof is pretty steep. I cannot imagine they would be tilting them much if at all. I know my house points southwest also. The roof is definitely in a perfect position for Solar. As for string inverters, I kind of like the ability to see what's going on (apps and online), and again to maximize power. Seems as though Micro or SolarEdge will produce power per day given that it does not require the entire string to be covered with sun to start producing. With the length of warranty, I was not seeing the advantages to be honest. That does not mean there is not an advantage, just that the faster replacement of a string inverter seems to eat up some of the cost difference from other systems. Again, I am just reading and comparing. I can come out of this thinking string is the best inverter you can buy later on today. So far, my best quote is 3.26/watt using 34 LG360, and Solaredge combo. Also I did read about Sunpower, but I am not looking to overpay either. Thanks again!

[J.P.M.]

Honestly, at this point I am not sure. I just obtained some quotes, but none of them mention the tilt. I can tell you that my roof is pretty steep. I cannot imagine they would be tilting them much if at all. I know my house points southwest also. The roof is definitely in a perfect position for Solar. As for string inverters, I kind of like the ability to see what's going on (apps and online), and again to maximize power. Seems as though Micro or SolarEdge will produce power per day given that it does not require the entire string to be covered with sun to start producing. With the length of warranty, I was not seeing the advantages to be honest. That does not mean there is not an advantage, just that the faster replacement of a string inverter seems to eat up some of the cost difference from other systems. Again, I am just reading and comparing. I can come out of this thinking string is the best inverter you can buy later on today. So far, my best quote is 3.26/watt using 34 LG360, and Solaredge combo. Also I did read about Sunpower, but I am not looking to overpay either. Thanks again!

I was working from your statement that your roof was "pretty flat", assuming that meant horizontal. My bad.

As for monitoring output, everyone is different, but many folks stop paying much attention to that feature as soon as the novelty wears off - about 2 weeks or so - and then ignore it. Meanwhile, if a string inverter fails, the loss may well be noticed a lot quicker due to a larger loss.

I respectfully suggest your read the book.

[desant89]

I was working from your statement that your roof was "pretty flat", assuming that meant horizontal. My bad.

As for monitoring output, everyone is different, but many folks stop paying much attention to that feature as soon as the novelty wears off - about 2 weeks or so - and then ignore it. Meanwhile, if a string inverter fails, the loss may well be noticed a lot quicker due to a larger loss.

I respectfully suggest your read the book.

ok, I read the book (2nd edition). There is a TON of great information in that book as far as making homes more efficient, the whole solar install, and selection process. However, as far as inverters go, I did not read anything that would make going with a string inverter an easy decision. Main reason is that the book is from 2010. Micro inverters were brand new, and there was no talk at all about power optimizers. Not saying string is not the way to go, I am just saying the book did not influence me one way or another. Awesome suggestion to read the book though. I learned tons about small projects that I may end up tackling myself once my system is in place. I can probably make enough changes to where my system will end up supplying all that I need. I am just getting more bids now. I think I may have a reputable company who does not sub anything out now. I will see what their final quote is like, and probably check out a few of their jobs in person before I commit to anything. I had about 7 bids so far (no site visits yet), and 5 were SolarEdge, and 2 Micro. None of them have yet to suggest string. Of course I am sure they all make more money on the more expensive options, and that is likely a driving force too. Thanks again, everything you are telling me is helping me greatly with this project.

[J.P.M.]

ok, I read the book (2nd edition). There is a TON of great information in that book as far as making homes more efficient, the whole solar install, and selection process. However, as far as inverters go, I did not read anything that would make going with a string inverter an easy decision. Main reason is that the book is from 2010. Micro inverters were brand new, and there was no talk at all about power optimizers. Not saying string is not the way to go, I am just saying the book did not influence me one way or another. Awesome suggestion to read the book though. I learned tons about small projects that I may end up tackling myself once my system is in place. I can probably make enough changes to where my system will end up supplying all that I need. I am just getting more bids now. I think I may have a reputable company who does not sub anything out now. I will see what their final quote is like, and probably check out a few of their jobs in person before I commit to anything. I had about 7 bids so far (no site visits yet), and 5 were SolarEdge, and 2 Micro. None of them have yet to suggest string. Of course I am sure they all make more money on the more expensive options, and that is likely a driving force too. Thanks again, everything you are telling me is helping me greatly with this project.

FWIW, you are more than welcome. Just keep the cart before the horse and keep in mind that the goal is a lower electric bill, not necessarily solar for it's own sake. PV is only one tool to that goal, and usually the most expensive one, therefore the last one.

Also, know the answers to the questions you ask vendors before you ask. You'll learn a lot more that way, all the way around. Read the book and you'll quickly come to find out you know more than most solar peddlers anyway. Use that to help pick a reliable vendor. That'll be your best insurance - but still no guarantee - of a quality install.

The basic discussion around micros vs. string inverters hasn't changed much, only the relative sizes and perhaps some better reliability history. For some, micros are good, others not so good. More FWIW, to me, no shade == no micros.

Good luck.

[Spektre]

<snip> Just keep the cart before the horse </snip>
Good luck.

Umm, hunh? Isn't that what you don't want?

[J.P.M.]

Umm, hunh? Isn't that what you don't want?

Sure isn't. Left out a word (don't, between Just and keep ). My apologies.

J.P.M.

[foo1bar]

As for monitoring output, everyone is different, but many folks stop paying much attention to that feature as soon as the novelty wears off - about 2 weeks or so - and then ignore it.

It's been just under 2 years and I still check it some... I'm a nerd so I'm probably more likely than most people to look.

I just checked it now and saw an error message from the inverter that was from 7 days ago.
7 days ago we had no power for almost all hours of sunlight. So the inverter noticed and flagged: "Inverter Energy Below Threshold Inverter 1 produced below 10.0 Wh in the last Day"
I also know I checked on the day we had the power outage - it was a way of checking if the power was back on at home.

I think it may be like fancy wheels on a car. Sure it's not really necessary. It's fun to look at and show off. And after a while you don't even really notice that you have them. But if you think it's a good choice for spending your money on that, its your money to spend so why not.

[desant89]

It's been just under 2 years and I still check it some... I'm a nerd so I'm probably more likely than most people to look.

I just checked it now and saw an error message from the inverter that was from 7 days ago.
7 days ago we had no power for almost all hours of sunlight. So the inverter noticed and flagged: "Inverter Energy Below Threshold Inverter 1 produced below 10.0 Wh in the last Day"
I also know I checked on the day we had the power outage - it was a way of checking if the power was back on at home.

I think it may be like fancy wheels on a car. Sure it's not really necessary. It's fun to look at and show off. And after a while you don't even really notice that you have them. But if you think it's a good choice for spending your money on that, its your money to spend so why not.

I am not sure exactly how much more money the Solaredge 11.4 inverter costs vs String, but the benefits of more time of production, and the individual panel monitoring seem worth it to me. I am a tech guy too, and think I will check it often. However, that is not the only reason I am going with it. There are plenty of discussions that led me to think there are some benefits over a string inverter. I actually will be signing tonight. Ended up at 3.00/watt (financed) which is the best price I've gotten so far. Company was referred to me on this forum. As of now (no site visit yet), I am looking at 34 LG365 panels, and the SolarEdge 11.4 with optimizers. Thanks!

[J.P.M.]

It's been just under 2 years and I still check it some... I'm a nerd so I'm probably more likely than most people to look.

I just checked it now and saw an error message from the inverter that was from 7 days ago.
7 days ago we had no power for almost all hours of sunlight. So the inverter noticed and flagged: "Inverter Energy Below Threshold Inverter 1 produced below 10.0 Wh in the last Day"
I also know I checked on the day we had the power outage - it was a way of checking if the power was back on at home.

I think it may be like fancy wheels on a car. Sure it's not really necessary. It's fun to look at and show off. And after a while you don't even really notice that you have them. But if you think it's a good choice for spending your money on that, its your money to spend so why not.

I'm not knocking reading and monitoring output. Quite the contrary, I believe it's one of the best ways to improve (reduce) use and increase system knowledge. I'm always a big fan of education. Hell, I've got all output from my system in 5 min. increments since startup, 10/17/2013, and I use it, or at least parts of that output, if not daily, at least several times/week.

My opinion about new users getting all excited about monitoring comes from watching over 100 and counting PV installs in my HOA, and noticing how many users were excited about, and often paid for monitoring, and then seeing most of that interest fall off after a short period of time. Mostly due to that, I've formed the opinion, and not surprised that, for maybe most, the novelty quickly wears off. So, I'm merely suggesting, for those cases, the added cost of monitoring if it is indeed a contract charge or after market purchase, that it may be a waste of financial resources. Not the end of the world however.

[Six4KilowWatt]

Quite honestly I think you need to compromise electrical output and mix your solar array. To heat a pool you should have a dedicated solar heating system. I think you will need to consider that option.

[J.P.M.]

Quite honestly I think you need to compromise electrical output and mix your solar array. To heat a pool you should have a dedicated solar heating system. I think you will need to consider that option.

Agreed. Using PV generated electricity to heat a pool is like using a gold bar for a paperweight when a lead bar is as fit for purpose. Ludicrous.

Solar thermal pool heaters made for that purpose may be cost effective. POV pool heaters - never.