Requesting Assistance/Comments on selecting between two proposals...

[Quinten]

Hello... Newbie here!

Before I take the plunge, I thought it would be a good idea to see what opinions there are on these two configurations from 2 local companies.

Current Annual demand is 21,520kW (Las Vegas, NV)

Both systems include a new Pentair VS or Hayward Echostar variable speed pool pump replacing a 1 speed 2hp pump (8hr/day runtime). Total cost is within $400 (1%) of each other at just under $40,000. Both systems are 41 panels in the same configuration with 1/2 of the panels facing south and the other 1/2 facing west. No shade.

The assumption is that the pool pump will reduce annual demand by at least 4000kw/yr bringing the target to 17520kw.

System 1

PV Panels: 41 x Kyocera Solar, Model: KD250GX-LFB
Inverters: 41 x Enphase Energy, Model: M215-60-208-S2x
Included: * Energy Option - VP: $1,150 (What exactly is this?)
Total Panel Area: 700 sq-ft
System Peak Power: 10.25 kW DC (9.84 kW AC, 8.805 kW CEC)
Annual Production: 17,630 kWh. Supplying 82% of annual electric use
Contract price $39,956 $3.9/watt, $3.79/watt with $1150 included option, $3.68/watt with pool pump + inc option ($1040)


System 2

PV Panels: 41 x Sunedision, Model:F275KyC
Inverters: Micro inverter (stated enphase, don't have the model #, on request) originally string inverter specified.
System Peak Power: 11.75 kW DC
Annual Production: 16,055 kWh. Supplying 80% of annual electric use
Contract price $39,542 $3.54/watt, $3.41/watt with pool pump ($1040)

Is system 1 being overly optimistic with annual production given lower panel output (250 vs 275) or is system 2 being conservative? Which panel (sunedison or kyoceya would be preferable or would they be considered comparable and not a basis for a decision?

[+3 Golfer]

Just a few comments. It looks like you are thinking conservation first which is good. By replacing your pool pump and running the variable speed pump maybe 1.5 hours at 2200 rpm for cleaning and 6.5 hours at 1200 rpm vs the single speed pump, you will likely be saving around 3500-4000 kWh a year (very smart investment). Since you had a single speed pump, it implies your home may be older. Have you had an energy audit done (your utility might offer a subsidized price of like $99).

As far as the PV system, why are you choosing to go with Enphase micro-inverters? String inverters will likely be cheaper and IMO a better choice.

Vendors typically are very conservative on system output. So, both systems will likely produce more kWh than their estimates. Are you aware of PVWatts. It's a simple program to run. Use a derating of 0.84 and see what results you get. You will have to make multiple runs if you have various panel orientation and sum the results.

[J.P.M.]

Hello... Newbie here!

Before I take the plunge, I thought it would be a good idea to see what opinions there are on these two configurations from 2 local companies.

Current Annual demand is 21,520kW (Las Vegas, NV)

Both systems include a new Pentair VS or Hayward Echostar variable speed pool pump replacing a 1 speed 2hp pump (8hr/day runtime). Total cost is within $400 (1%) of each other at just under $40,000. Both systems are 41 panels in the same configuration with 1/2 of the panels facing south and the other 1/2 facing west. No shade.

The assumption is that the pool pump will reduce annual demand by at least 4000kw/yr bringing the target to 17520kw.

System 1

PV Panels: 41 x Kyocera Solar, Model: KD250GX-LFB
Inverters: 41 x Enphase Energy, Model: M215-60-208-S2x
Included: * Energy Option - VP: $1,150 (What exactly is this?)
Total Panel Area: 700 sq-ft
System Peak Power: 10.25 kW DC (9.84 kW AC, 8.805 kW CEC)
Annual Production: 17,630 kWh. Supplying 82% of annual electric use
Contract price $39,956 $3.9/watt, $3.79/watt with $1150 included option, $3.68/watt with pool pump + inc option ($1040)


System 2

PV Panels: 41 x Sunedision, Model:F275KyC
Inverters: Micro inverter (stated enphase, don't have the model #, on request) originally string inverter specified.
System Peak Power: 11.75 kW DC
Annual Production: 16,055 kWh. Supplying 80% of annual electric use
Contract price $39,542 $3.54/watt, $3.41/watt with pool pump ($1040)

Is system 1 being overly optimistic with annual production given lower panel output (250 vs 275) or is system 2 being conservative? Which panel (sunedison or kyoceya would be preferable or would they be considered comparable and not a basis for a decision?

+1 on +3 Golfer comments on conservation.

Considering most systems under equal orientations and duty produce about the same annual output per D.C (Nameplate) Watt, one or both of these quotes may be off. #1 = 1.72 Kwhrs/yr. per D.C. Watt. # 2 = 1.37 kWhrs./yr. per D.C. Watt. While some variation is to be expected and both are estimates, a 25% diff. seems a bit much. FWIW, I'd bet closer to the higher #, or split the diif. and add 5 or 10% to that #.

Depending on tilt & orientation, system 1 seems more realistic in terms of output SWAG. System 2 seems a bit low on prediction if same orientation as system #1. #2 may be padding the quote by underpredicting performance. Happens quite often. #1 may be doing the same but to a lesser degree. Could be one's under/one's over.

Unless you've got shade, I'd skip the micro inverters in favor of string. especially in Vegas. due to temps. Besides, you'll probably save a few $$'s

I'd also compare apples/apples and compare system costs by themselves w/out muddying the waters w/pumps/options/whatever.

If it was me, I'd get & install the pump now, wait on the solar and then get more and/or requotes about 4-6 mo. w/new usage #'s after the pump goes in and more conservation.

Don't know much about solar prices around Vegas, but the $$#'s you quote here don't seem way off compared to my neighborhood. Still, more quotes won't hurt. Don't be rushed by anyone, including yourself.

Also, it's bad to pay too much, worse to pay too little. Go with a reputable installer. Really cheap insurance. You won't be sorry. A little more spent there pays big dividends.

Further to +3 's comments: take a shot at PVWatts as he suggests. I'd suggest use a .84 derate for starters. You'll know what I'm writing about when you get there.

[Quinten]

Thanks for the comments... I liked the enphase energy system and monitoring application. I did have the second quote with a string converter at first, told them I wanted the enphase and it was reworked and also lowered so I'm aware there is some wiggle room.

I do need a pool pump since mine leaks a little, but can wait. The pump does run a solar heater and also a suction side cleaner. I will probably not see quite the expected savings when trying to heat the pool in the spring and fall with the higher speed required, but should be considerably better. The pool pump comes with a $250 NV Energy rebate only if installed by one of their approved contractors (which is over 30). I emailed all of them and found the least expensive was $1040 installed with the NV energy rebate applied. One company replied that they only installed the pump with solar, so this all began

From a cost standpoint now... I average ~ $250/mo in electric. Both proposals will finance with a combo loan (the 30% fed tax credit as 12/mo same as cash) then the balance of ~ $28k @ 2.9% for 12/yrs. The payment on that is $229 - $231 mo. so the average net cost per month should be under $25. If all PEC's are sold and applied to the balance, the term should be reduced to ~ 10 years. The Home value increase is excluded from property tax and should be substantial for at least the first 10 years ($25 - $30k +) ... After that I read that solar (as it ages) decreases some as it is viewed as aging electronics, but will still be a significant amount added to the home value. I will also save $1040 out of pocket up front on a pool pump. I don't need to get the absolute best deal, but I also don't like to have any idea on what kind of deal I am getting.

I did see that NV energy will start their 'incentives" again mid year. Not sure what they are going to be and may require surrendering the PEC's so I will be trying to find out info on that. Their incentive period may also be quite limited, so it will be good to jump right in if it is a beneficial deal.

Currently rates are a flat $.118/kw on the plan I am on.

NV Energy uses net metering, if swapped to Time of use, power generated during peak summer should mostly be off of solar, any excess will be at the rates in place during that time...

Summer peak rates are: July-Sept (1-6pm .387/kw), mid peak (10am - 1pm .189/kw), all other hours .0527/kw
Winter peak rates are: Oct-June (5 - 9pm .071/kw), all other times .0527

I see I get long winded... Thanks in advance for any comments/suggestions!

[J.P.M.]

Thanks for the comments... I liked the enphase energy system and monitoring application. I did have the second quote with a string converter at first, told them I wanted the enphase and it was reworked and also lowered so I'm aware there is some wiggle room.

I do need a pool pump since mine leaks a little, but can wait. The pump does run a solar heater and also a suction side cleaner. I will probably not see quite the expected savings when trying to heat the pool in the spring and fall with the higher speed required, but should be considerably better. The pool pump comes with a $250 NV Energy rebate only if installed by one of their approved contractors (which is over 30). I emailed all of them and found the least expensive was $1040 installed with the NV energy rebate applied. One company replied that they only installed the pump with solar, so this all began

From a cost standpoint now... I average ~ $250/mo in electric. Both proposals will finance with a combo loan (the 30% fed tax credit as 12/mo same as cash) then the balance of ~ $28k @ 2.9% for 12/yrs. The payment on that is $229 - $231 mo. so the average net cost per month should be under $25. If all PEC's are sold and applied to the balance, the term should be reduced to ~ 10 years. The Home value increase is excluded from property tax and should be substantial for at least the first 10 years ($25 - $30k +) ... After that I read that solar (as it ages) decreases some as it is viewed as aging electronics, but will still be a significant amount added to the home value. I will also save $1040 out of pocket up front on a pool pump. I don't need to get the absolute best deal, but I also don't like to have any idea on what kind of deal I am getting.

I did see that NV energy will start their 'incentives" again mid year. Not sure what they are going to be and may require surrendering the PEC's so I will be trying to find out info on that. Their incentive period may also be quite limited, so it will be good to jump right in if it is a beneficial deal.

Currently rates are a flat $.118/kw on the plan I am on.

NV Energy uses net metering, if swapped to Time of use, power generated during peak summer should mostly be off of solar, any excess will be at the rates in place during that time...

Summer peak rates are: July-Sept (1-6pm .387/kw), mid peak (10am - 1pm .189/kw), all other hours .0527/kw
Winter peak rates are: Oct-June (5 - 9pm .071/kw), all other times .0527

I see I get long winded... Thanks in advance for any comments/suggestions!

To be clear, I'd get the pump now.

[Quinten]

Getting the pool pump now would depend on the costs of the systems without the pool pump... I'm going to check on that too. Thanks. I'm trying to also determine if there is any significant difference between the sunedison and kyrocea panels (besides the 275 - 250 rating). Both considered same quality?

[+3 Golfer]

To be clear, I'd get the pump now.

Agreed, get the pool pump. Payback will be much quicker than PV solar.

When I moved into my home nearly 2 years ago, the pool had a 2 HP single speed pump. It used about 2 kW+ @3450 rpm. About one month later I put in a Hayward Ecostar 2 HP. I graphed the actual pump electric load for various speeds (as displayed on the control panel) in the curve below. The "pump affinity law" says that if you cut rpm in 1/2: flow drops 1/2, and power drops 1/8. My power decline for 50% drop in load is not quite as large as the 1/8 (as shown in the curve) but close enough.

You may be able to cut the flow rate with the variable speed to the solar heaters and not lose many btus but you will reduce the power requirements considerably. I believe in the Hayward you can input 8 separate programs to perhaps set speed proportional to solar insolation levels for the time of day. Just cutting rpm from 3450 to 3000 (3000/3450) = 0.87, should cut load to about (0.87)^3 = 0.66 or from 2 kW to 1.33 kW. If you can drop to 2700 rpm, the pump load drops to slightly less than 1 kW. So, even with running the pump for 8 hours per day for solar heating, you will likely be able to optimize rpm for time of day and get quite a bit of savings.

As far as panel quality, my previous PV solar system has Kyrocera panels with no issues after 4 years. I know you want someone to point you to a study or long term testing that ranks panels. I haven't seen any such things and besides manufacturing processes likely change every few years either to cut costs or improve quality. Who is to say last years 240W panels are the same quality as this years 250W panels.

Be careful on your assumption on increase in home value for the first 10 years. I doubt most people will pay what it cost to install a solar system nor will they pay the PV of the electric savings. I sold a home with solar. It makes it easier to sell a home with solar than one without but like most anything, why pay $25k more than an equivalent home without solar when the payback may be a decade away (and they may move prior to that).

Hayward Ecostar Watts vs RPM.JPG

[J.P.M.]

Getting the pool pump now would depend on the costs of the systems without the pool pump... I'm going to check on that too. Thanks. I'm trying to also determine if there is any significant difference between the sunedison and kyrocea panels (besides the 275 - 250 rating). Both considered same quality?

Peddler's hype aside, I doubt if there is any difference in the product quality that is measureable and quantifiable in a meaningful and verifiable way once either is installed. I'd spend more time getting information about installers. IMO, their quality and professionalism are more important than the difference between 2 good quality panels from established mfgrs. I will say however that the Sunedison website seems a bit skimpy on info. Datasheets were not easy to find.

[Quinten]

Thanks... I did contact the two vendors that gave me a proposal and let them know I would be meeting with a couple more this week, then have them back out to go over the installation as that appears it may be a the deciding factor.

Regarding installation... This will be on a Spanish tile roof with the panels in two ~ 20 panel arrays (one facing south on the side of the garage and the other facing west on the back roof)... What would be the preferable mounting system if there are various methods to use? I'm planning on using enphase micro inverters and wiring will be through the attic.

What aspects of the installation should I be looking at when trying to determine who should be doing the work? Besides being licensed contractors, seeing completed installation and checking reviews posted online... What else might be an indication of the type of installation to expect.

[J.P.M.]

Thanks... I did contact the two vendors that gave me a proposal and let them know I would be meeting with a couple more this week, then have them back out to go over the installation as that appears it may be a the deciding factor.

Regarding installation... This will be on a Spanish tile roof with the panels in two ~ 20 panel arrays (one facing south on the side of the garage and the other facing west on the back roof)... What would be the preferable mounting system if there are various methods to use? I'm planning on using enphase micro inverters and wiring will be through the attic.

What aspects of the installation should I be looking at when trying to determine who should be doing the work? Besides being licensed contractors, seeing completed installation and checking reviews posted online... What else might be an indication of the type of installation to expect.

Provided things are reasonably standard in terms of your roof, a good installer will likely use an aluminum rail racking system. Details are pretty common and well known. Given your climate and choice of micro inverters, if it was me I'd consider two mods. to what is common :

1.) If at all possible, set the panel spacing and micro location such that each micro is accessible and serviceable without removing any panels.

2.) Assuming the panel arrays will be parallel to the plane of the roof they are mounted on, consider using standoffs to allow better air circulation under the panels. This, in theory, will TEND to lower the panel temps. and probably the microinverter temps. Things will probably run cooler, longer and more efficiently. It may look a bit funky at first, but after a week or so, you and most everyone else won't notice it.

Think ahead. Think smart. Think serviceability

Before I did anything else, including getting more quotes, I'd get my roof, at least the portion of it that will be under or adjacent to the panels inspected and serviced as needed thinking 20 - 25 yrs. ahead. Solar will last a long time. Will the roof under the panels last 25 yrs ? How about the rest of it ? Roof inspection/service is one of those PITA things that is probably unavoidable - pay me now/pay me later type stuff. Cheap insurance. You won't be sorry.

I'd take vendor supplied references w/ a big grain of salt. Same for online reviews. The vendor references are useless. The online reviews are unverifiable and thus also mostly useless, and may be written by the vendor's otherwise unemployable brother-in-law or a clueless customer who may have gotten a decent job but had unrealistic expectations. I'd rather spend my time interviewing vendors, forming my own opinions and taking my best shot.

[HX_Guy]

By replacing your pool pump and running the variable speed pump maybe 1.5 hours at 2200 rpm for cleaning and 6.5 hours at 1200 rpm vs the single speed pump, you will likely be saving around 3500-4000 kWh a year (very smart investment).

Sorry for the slight thread jack but I caught this bit here and have a couple questions.

We had a pool built in Feb of this year and it has a Pentair Intelliflo Variable Speed Pump. From what the pool company told me, the variable speed is for cleaning vs water feature use, they never mentioned using a lower speed during the nightly "cleaning cycle". I just checked and there are two speeds setup, one at 2950 RPM for 5.5 hours per night, and a second speed at 1200 RPM that is used strictly when I run the water feature.

Is that crazy to run the pump at 2950 for 5.5 hours per night? The pool is a tad under 10,000 gallons and has in-floor pop up cleaners if it makes a difference.

[Quinten]

The higher speed would be to run the popup cleaners... Depending how long you pool needs them running to keep clean would determine the duration. 5.5 hours seems like a long time to clean the pool. Running the pump at lower speed for a longer duration will keep the water filtered. I was planning on running at low speed for 12+ hours a day, then a higher speed for solar and cleaning when needed (2 hours or less a day).

[russ]

Typically I see 4 turnovers of the water per day recommended - that gives good filtration and sanitation.

[+3 Golfer]

Sorry for the slight thread jack but I caught this bit here and have a couple questions.

We had a pool built in Feb of this year and it has a Pentair Intelliflo Variable Speed Pump. From what the pool company told me, the variable speed is for cleaning vs water feature use, they never mentioned using a lower speed during the nightly "cleaning cycle". I just checked and there are two speeds setup, one at 2950 RPM for 5.5 hours per night, and a second speed at 1200 RPM that is used strictly when I run the water feature.

Is that crazy to run the pump at 2950 for 5.5 hours per night? The pool is a tad under 10,000 gallons and has in-floor pop up cleaners if it makes a difference.

Typically I see 4 turnovers of the water per day recommended - that gives good filtration and sanitation.

Well, if it's the YMCA's pool then 4 turnovers a day is probably necessary. Also, note the chlorine smell from the high levels of chlorine in the Y's pool - for good reason.

A typical homeowner's pool should be fine with one turnover a day for family use. If the pool isn't crystal clear, then one should increase turnovers and perhaps remove phosphates and kill algae. Since flow isn't exactly known at various speeds, I'm conservative in estimating flow and likely have a turnover of 1.2 times a day for my 14,000 gallon pool and spa. This is 45 minutes at 1900 rpm and 45 minutes at 2400 rpm for bottom and side cleaning by my "Baracuda" and about 5-6 hours at 1200 rpm for balance of turnover. As long as my pool stays crystal clear, turnover is fine. After a day or two of significant wind and collection of dust and tree debris in the pool, I do manually run the baracuda for 3-4 hours and may also get my vacuum attachment and manually clean the bottom. When I add chemicals, I manually run the pump at around 1600 rpm for 2-3 hours.

HX_Guy, 2950 rpm for 5.5 hours (probably 7.7 kWh a day) is a lot of power consumption (2800 kWh a year vs my 680 kWh for pool cleaning). I can't believe it takes that long for the system to "blow" the debris to the drains. But since it also blows the lighter, smaller debris into the pool water, it may take 2-3 turnovers to adequately filter such out of the water.

I just read the "marketing BS" as to why the popup system is better than a conventional suction cleaning system. About the only benefit I see is one supposedly has to do nothing as far as pool cleaning maintenance - but supposedly it has issues pushing leaves and twigs.

I can't find much info on popup cleaners (pressure drop). Do you have a pressure gauge on your sand filter? If so what does it read at 2950 rpm when cleaning and without cleaning? My suggestion is to cut the time down and see if the pool remains crystal clear and the bottom clean. My guess is the popup system needs the high pressure developed from 2950 rpm so you may not be able to cut rpm back but you might try and see what happens. My guess is the flow rate at 2950 has to be at least 80 gallons a minute = 4800 gallons /hour and 26,400 gallons /5.5 hours or 2.6 turnovers a day minimum. The flow might be even higher though. 100 gallons per minute (25% more) would give a turnover of about 3.3 X per day.

[HX_Guy]

Thanks Golfer. The only reason we went with the pop ups were aesthetics, hate the crawler and the tubing that goes along with it, plus we liked the lifetime warranty. Our old pool had the crawler and it seemed every year or two we had to replace parts on it.

You probably have a point about the high RPMS to create enough pressure for the pop ups to work properly, so I dont know if I can turn down the speed, but I can probably reduce the amount of time it runs at that high speed and then do a few hours for just cycling the water. I'll tinker with it and see what happens.