LG vs Panasonic vs Mission Solar vs Trina

[Ampster]

1/3 the cost? What string inverters are you using? Sounds like a great deal. I see them being 33% to 50% less expensive than the cost of microinverters, and given most string inverters last about 10 years, I would expect the lifetime cost of microinverters to typically be less.

Capacitors are a weak point in many electronics. Enphase has studied them a lot (paper here: https://enphase.com/sites/default/fi...acitorLife.pdf).

In this thread I was talking about the operating cost of a heat pump water heater versus a resistive element. I was supporting your statement and offering a counter argument to @Mike90250 who lives off grid and has different cost factors than someone on the grid. His argument makes sense for someone in his situation, but not necessarily for someone in a temperate environment in an all electric home.

I think the discussion about string inverters vs microinverters is in another thread. I don't have a strong opinion one way or the other about string inverters vs microinverters. I have a combination of both in my current residence, plus my main system is a SolarEdge with Optimizers.

[mjlef]

I have experienced that 1/3 cost factor which makes the payback faster especially in California with high rates. I don't know if mine will last longer than a resistive unit but it may not matter if the payback is faster. I have installed 3 and the oldest is still going strong after 8 years. Another has been in service 4 years and already paid for itself.

1/3 the cost? What string inverters are you using? Sounds like a great deal. I see them being 33% to 50% less expensive than the cost of microinverters, and given most string inverters last about 10 years, I would expect the lifetime cost of microinverters to typically be less.

Capacitors are a weak point in many electronics. Enphase has studied them a lot (paper here: https://enphase.com/sites/default/fi...acitorLife.pdf).

[Ampster]

I have experienced that 1/3 cost factor which makes the payback faster especially in California with high rates. I don't know if mine will last longer than a resistive unit but it may not matter if the payback is faster. I have installed 3 and the oldest is still going strong after 8 years. Another has been in service 4 years and already paid for itself.

[Mike90250]

Another great energy saver is a heat pump hot water heater They typically use less than 1/3 the electricity, last longer than regular water heaters too. Mark

I'm going to call your bluff on that one. Not sure how you figure a mechanical heat pump will last longer than a Calrod restive element. And to repair the electric element is $30 and and hour of labor. When the heatpump water heaters go, there generally is no repair, toss it and get another.

[mjlef]

Our air conditioner was replaced in 2014, so it's not using R22. Are you suggesting that my electric bill is high for a 1968-built home in South Florida with a swimming pool? I've frequently commented to my wife about this wrt the thermostat setting, but there's only so much I can do short of getting a divorce.

The average FPL customer uses 14,000 kWh a year, the median customer uses 11,000. My pool pump only accounts for an extra 1000-2000 kWh a year. God only knows how much of the electric bill is due to the wife or kids turning down the thermostat to 70 degrees! I will say that the bill is a lot better after spending $20k on new windows and $4000 on new ducts and attic insulation.

I'd really be interested in hearing about the bills for other single-family residences in South Florida. Do crazy thermostat settings and excessive electricity use count as "pain and suffering" in divorce decrees?

If you have not heard about radiant barriers, look it up. In Florida they typically run AC ducts through the attic (the hottest part of the house). And often they are leaky ducts. Radiant Barrier stapled to attic rafters both reflects heat back out through the roof, and lowers infrared emissions from the roof to the attic deck, keeping the attics much cooler. Easy to install assuming your attic has room to get around. Buy a can or two of spray foam and as you have it installed, feel for duct leaks, and seal them as you go. Start at say 5 am when it is cooler in the attic, but turn your AC way down so it is running. Makes it easy to feel for the leaks. You can typically save the cost of the barrier in one year, assuming you do it yourself.

fpl can do a free energy audit for you, and have rebates on things like extra attic insulation. Also they have a program called "On Call" where they install devices to shut down pool pump, AC and hot water heaters on day when there is too much demand. I have in on my hot water heater, and they seem to have never activated it. They credit you a fixed amount each month (for example a hot water heater cuts your electric bill $1.50).

Another great energy saver is a heat pump hot water heater They typically use less than 1/3 the electricity, last longer than regular water heaters too.

Mark

[BoloMKXXVIII]

My FPL bill peaks in summer at about $150/month. The house is only 1850 sq.ft. and no pool. New roof (white shingles), maxed out the insulation in the attic, house is also white with only a bit of color trim. Impact windows (make a huge difference in heat transmission), two year old A/C unit, LED light bulbs, etc. Programmable thermostat so we are not cooling a lot when nobody is home. No solar panels other than backup power to charge a small LiFePo4 battery to power my CPAP and charge cell phones in case of long term power disruption (i.e. hurricanes). Winter power bills less than $100. Efficiency is the way to go. I understand the WAF is a big factor. Perhaps if you let her know how much you could be saving in pairs of shoes it would sink in. (no offense intended).

[bcroe]

I also replaced my AC unit in 2014. The replacement had a SEER of 13, honestly it was a disappointment
in several ways. In 2018 I installed heat pumps with a SEER of 33. These were able to reduce my HVAC
energy by more than half, along with several other benefits. What are your numbers?

Get numbers, how many of your KWH are going to air cond., what are the numbers
for the other stuff? Find out the SEER or EER or COP of your current equipment.

The suggestions above of feeding perhaps 15KW of E and W panels into an 11KW inverter works
when set up right. Been doing it here for years. Bruce Roe

[lensman]

I am wondering if you are using a huge amount of KWH running an obsolete air cond
system, esp one using R22? If so you could cut that usage in half by going to mini
split R410A technology, and get several other advantages too. It is even possible to
get units powered directly from solar panels, so this would not add to your 11.5KW
limit. These have a dual capability of partial or all line power usage if lacking sun.

They can heat too, at a lower cost than propane. Bruce Roe

Our air conditioner was replaced in 2014, so it's not using R22. Are you suggesting that my electric bill is high for a 1968-built home in South Florida with a swimming pool? I've frequently commented to my wife about this wrt the thermostat setting, but there's only so much I can do short of getting a divorce.

The average FPL customer uses 14,000 kWh a year, the median customer uses 11,000. My pool pump only accounts for an extra 1000-2000 kWh a year. God only knows how much of the electric bill is due to the wife or kids turning down the thermostat to 70 degrees! I will say that the bill is a lot better after spending $20k on new windows and $4000 on new ducts and attic insulation.

I'd really be interested in hearing about the bills for other single-family residences in South Florida. Do crazy thermostat settings and excessive electricity use count as "pain and suffering" in divorce decrees?

[bcroe]

I am wondering if you are using a huge amount of KWH running an obsolete air cond
system, esp one using R22? If so you could cut that usage in half by going to mini
split R410A technology, and get several other advantages too. It is even possible to
get units powered directly from solar panels, so this would not add to your 11.5KW
limit. These have a dual capability of partial or all line power usage if lacking sun.

They can heat too, at a lower cost than propane. Bruce Roe

[lensman]

JSchnee21,

Thanks so much for your analysis. Great questions!

Yes, Florida Power & Light is my power company and I want to stay below their 11.5 kW limit for a Tier 1 system. They require a $1 million general liability policy and $400 fee for larger systems.

My annual usage is down to 22,000 kWh after all the efficiency mods we've done, including a multi-speed pool pump. I'd guess I'm 5-7 years away from replacing the AC system. Beyond this I'll have to continue my fight with my wife and kids about the thermostat settings. We're also getting a Sense electricity monitor installed so there's hope for finding other savings.

The modeling in the proposals is fairly accurate to what I did myself in pvwatts. I came up with 16,483 kWh/yr and the installers production estimate is 16,490 kWh/yr for the 11.5 kW system. It's actually remarkably similar. That's about 75% of my past year's usage. I think my usage is a little down from what I entered in energysage late last year, accounting for the 5% coverage difference.

I did some shade modeling using shadowcalculator.eu and it looks to me like there could be some tree shade issues before 10 am and after 3:00 pm from November through January.

I got a proposed layout from the installer #2. They said they could sub in Panasonic 330 watt HITs for another $3k, taking me to $2.95 per watt for that bid, which includes Enphase micro-inverters. At $0.12 per kWh electricity, my payback period will be about 11 years.
Screen Shot 2019-06-17 at 1.35.22 PM.png

[JSchnee21]

One other comment, you list your percentage of bill usage next to the PV DC kW at STC. Just making sure you know that you cannot compare these two numbers. Your annual PoCo usage is in MWh per year (Mega Watt Hours). You cannot compare this to the DC kW rating of the array. Based on your home's latitude, and the orientation and inclination of your roof faces, you must model the potential output of the array. This will give you the expected production (in kWh or MWh) based on the size in kW of your array.

How many MWh do you use per year? And what is the cost per kWh?

You can model the production (of each roof face separately) on PVWatts

https://pvwatts.nrel.gov/

Or using the Solar Edge designer tool (which you have to register for)

As a very, very, very rough rule of thumb, depending on location, shading, angle, and other factors, the production of a PV system in MWh will be anywhere from 0.7x to 1.6x the DC kW rating of the array.

For example, where I live in NJ, based on my roof orientation, inclination, and shading, my 12.2kW array only produces ~11-12 MWh per year. But a local colleague of mine with a more optimal setup (less shade, better inclination, etc.) gets a similar level of production from his 9kW array.

Here's my system for example

https://pvoutput.org/list.jsp?id=58372&sid=52103

His lifetime, average, daily efficiency (kWh produced per DC kW of PV Array) is 3.614kWh/kW verses my 2.638kWh/kW. Needless to say his ROI is much better, too, given the smaller total investment for the smaller system, and choice of mid-tier panels.

But I'm still happy with my system. I got the panels I wanted and needed to maximize production on my tiny roof. We both used the same installer, After covering ever square foot of it with 37 panels, I'm still only able to offset ~85% of my annual consumption. I do have an old HVAC. No EV or pool. New windows, roof, insulation, home energy audit with Energy Star, etc. Still electric rates in NJ are very low ~0.09kW plus ~0.04 for transmission. But we have SREC credits to help defray the cost of solar. So I should break even in about 5 or 6 years from now (system installed in June 2017).

[JSchnee21]

If it were me, even though you plan to replace the HVAC with more efficient units, I would still target a larger array that covers more like 90-95% of anticipated usage -- it's hot and humid in FL. Do you have any EV's now? In 10yrs or less, I would expect at least 0.5 EV vehicles per household, perhaps more in more affluent households. EV's use a lot of electricity.

I see you have a pool as well. Do you have a multispeed, 240VAC pool pump? These can save a lot of electricity as well.

Is North up in your picture?

Based on your electrical rates and current consumption, after the federal rebate on the array (30%), how many years will it take to break even based on your current quotes? Will you still be living there by then?

I'd lean towards SolarEdge. Given that it looks like most of your panels are East/West. You could probably go up to ~15kW on the 11.4kW HD inverter. OR, split your array into two separate 7600W inverters (W+1/2 of S), (E+1/2 of S). But Enphase is fine, too.

Does you PoCo have a limit for the size of residential Grid-Tied systemsl? Some PoCo's require extra insurance, fees, etc. above a certain size (e.g. 10, 12, or 15kW)

$2.90 for Panasonic is a very good price. Not so much for LG Neon2. LG Neon R is more than Panasonic. Lots of other less expensive panels -- Trina, Jinko, Hanwha, etc. are good too, in the 2.60-2.80 range. I cannot comment on Mission Solar, but if it were me, I'd probably pass. Asian electronics are usually much better/more reliable than American.

Are panel aesthetics important? Black frames? Silver frames? I would stick with white backsheets in such a hot climate. The Panasonics and LG Neon R have great thermal coefficients. Note that many of the new LG's (and any 72-cell panels) are physically larger than "normal." So sometimes, when they come to actually measure your roof, it doesn't quite fit like the salesman said it would.

[Mike90250]

Whatever you get, you have 3 separate roof planes (E, S, W) and will need at least 3 MPPT channels

Maybe the trees have such an impact, you need microinverters. The pic, to me, (I'm assuming N is at the top) shows that only the E & W arrays are going to be useful and the 2 small S arrays are going to be in shade a lot.

You need a good shade analyisis, it may not be a good site for solar, except for the un shaded areas. When those trees grow, you will have even more shade

[lensman]

That older quote with 70 pv modules is likely about 17.5kW (assuming 250w PV modules )
Now you are looking at 3 quotes of about 11.5kW
Have you made the house more efficient?

Also note that those TSM-340DD14A are 72 cell modules not 60 like your other two quotes.

Did you leave out a quote? your subject mentions panasonic..

Hi @ButchDeal,

Yeah, in the intervening year and a half we installed new windows, replaced our ducts, blew insulation into the attic and replaced the roof. This took down our electric bill by a quarter to a third. Also, that older quote was for 100% coverage and the newer ones are all around 70%, which I feel is a "safer" number since I anticipate getting a higher efficiency central AC compressor the next time we replace it.

I added in the information on the Panasonic modules that Vendor 1 just sent me.

[ButchDeal]

That older quote with 70 pv modules is likely about 17.5kW (assuming 250w PV modules )
Now you are looking at 3 quotes of about 11.5kW
Have you made the house more efficient?

Also note that those TSM-340DD14A are 72 cell modules not 60 like your other two quotes.

Did you leave out a quote? your subject mentions panasonic..