Advice needed for system install

[dcchapman7]

- also posted this in new member intro section -

Have been doing a lot of research on solar the last few weeks, getting bids, running system sizes through PVwatts - some background before asking about the estimates I got: my home is in Fresno, CA, 2069 sq ft, our annual consumption was 9400 kwh last year, average monthly electric bill with PG & E about $155 (annual cost - $1860). Our only options for a roof mount are east and west facing due to very large trees in a neighbors yard that shade the south side of the house - these trees eliminate the option of installing on that end and also do bring some shade on the east and west sides especially in the winter. We are interested in an larger system that would produce well above our current consumption (margin enough to offset the electrical costs of running a hot tub - those we've talked to have suggested an extra 100-200 kw/mth more?) Think I have narrowed down quotes to 2 companies at this point - here are the details:

Option A) 8.8 kW system - Canadian Solar 325W - (CS6X-325p) - 27 panels
with Solar Edge inverter and optimizers
Cost - $24,132 - $2.74/W
Company has been around since 2008 - fairly solid reviews

Option B) 8.8 kW system - Hanwa 340W - (Q.Plus L-G4.2) - 26 panels
Solar Edge inverter and optimizers or Enphase microinverters
Cost - $21,780 - $2.47/W
Company has been around since 1970 - solid reviews (does heating and air conditioning, started doing solar around 2008)

Questions with the estimates -

1) Canadian Solar vs. Hanwa - thoughts on if Canadian Solar is worth the extra cost? Either companies' viability? Thoughts on if these are good prices for either brand?

2) Solar edge inverter with optimizers vs. enphase microinverters - have been advised by Company A not to go with microinverters due to temperature extremes in Fresno, that they will inevitably fail even though they have been tested in extreme temp environments and also there would be multiple points of failure instead of just one. It sounds like from the reading I've done, optimizers have less electronics in them and are less prone to fail. Company B will do either microinverters or optimizers for us, but have mostly used microinverters and they do offer a 25 year complete warranty on all parts and labor. Which do you think is the better choice? Is there an advantage to either with our shading issues?

3) Regarding running a hot tub, is the system sized too big or too small or just right based on our current usage?

4) We have an attached Duralum patio cover on the west side of the house big enough for 13 panels, am in the process of having one of the companies check with the county (with whom we pulled a permit when the patio cover was installed in 2014) if the engineering is sufficient to support the weight of the panels. Have considered that installing on the west facing patio cover would mean more production during peak TOU hours (with NEM 2.0), but then not sure about need for tilting panels on the patio cover due to only about 2.5% slope of cover (PVwatts actually shows better production with zero tilt than 20 degree - our roof pitch is 4-5/12). It sounds like tilting would be wise as far as the panels staying cleaner and that tilting should enable better production overall?...not sure what I'm' seeing on PVwatts then...If installing on the patio cover is an option, what are your thoughts on doing this vs on the east facing roof? One of the companies mentioned having all the panels installed on the west side being better for resale if the patio cover is an option...

Sorry if the post is too overloaded with info, wasn't sure how much detail to give or how many questions to ask in the first post. Appreciate any feedback and thoughts.

[J.P.M.]

Are the prices before of after fed. solar tax credit ? They seem maybe a bit low. Not a bad thing necessarily, but I'd make sure of what I was buying, and more sure of what shows up in my driveway for installation.

The weight is probably part of, but perhaps, depending on the array tilt and distance to the patio cover, not the biggest issue - the larger issue being the wind and to probably a lesser extent, the seismic loadings, especially if an array is at a tilt that's different from or non parallel to, and/or more than ~ 6"- 8" off the mounting surface. Patio covers may/may not be sufficiently robust to take additional loadings.

Make sure you're using correct inputs to PVWatts, and be careful about what you use for a per kWh price for T.O.U. PVWats prices don't automatically reflect T.O.U. rates. Doing your own is a bit of a PITA, but probably necessary if you want good results (GIGO). And keep I mind that the T.O.U. times and rates will change in the future. Using most current CA T.O.U. rates and times, and contrary to what you may have been told, led to believe, read, or intuitively may believe, west facing arrays (270 deg. az.) will usually not produce as much output, or for T.O.U. considerations, produce as much revenue (that is, offset as much of an electric bill) as south facing arrays (180 deg. az.). Currently, and very approximately, theoretical optimum azimuth for max. annual production is probably closer to very ~ 200-210 deg. az. with a tilt very approximately at local latitude +/- a few degrees. If you are like most folks, you're pretty well stuck, at least in your own mind, but probably by practical limitations as well to the roof(s) and roof azimuths/tilts you have.

Also know that, while it's your money/choice/life and NOMB or concern, if one goal is to minimize the amount of assets spent on paying electric bills over the long term, oversizing an array will be counterproductive to achieving that goal.

[dcchapman7]

Thanks for the feedback - Prices are before the federal tax credit - have confirmed panel make/model with companies and will at delivery if we go ahead. Do you think the Hanwa's are a better deal?

Company A did confirm today with the county who permitted the patio cover and has the engineering specs for it that it would be okay to mount the 13 panels on it - Do you think this an advantage over the mounting them on the east facing roof? (my hesitations on mounting on the east facing roof is off peak production, more to remove when eventually replacing the roof (at least 15-20 yrs away) and possible decrease in resale value from aesthetics)...

Again interest in oversizing the array would be primarily for offsetting costs for running a hot tub. Do you think the system size has enough margin/too much/too little? - PV watts shows average production running different panel location scenarios/tilts and 20% losses at around 10,500 - 11,000 kw. - an extra 1100 - 1600 kw a year...

Last, thoughts on optimizers vs. microinverters for Fresno, CA climate?

[J.P.M.]

Thanks for the feedback - Prices are before the federal tax credit - have confirmed panel make/model with companies and will at delivery if we go ahead. Do you think the Hanwa's are a better deal?

Company A did confirm today with the county who permitted the patio cover and has the engineering specs for it that it would be okay to mount the 13 panels on it - Do you think this an advantage over the mounting them on the east facing roof? (my hesitations on mounting on the east facing roof is off peak production, more to remove when eventually replacing the roof (at least 15-20 yrs away) and possible decrease in resale value from aesthetics)...

Again interest in oversizing the array would be primarily for offsetting costs for running a hot tub. Do you think the system size has enough margin/too much/too little? - PV watts shows average production running different panel location scenarios/tilts and 20% losses at around 10,500 - 11,000 kw. - an extra 1100 - 1600 kw a year...

Last, thoughts on optimizers vs. microinverters for Fresno, CA climate?

I'm not a big fan of micros, to the point of saying I think they suck, are oversold by vendors and are a poor choice for all but a few applications, particularly in hot climates. String inverters a re a better long term choice. But,opinions are like noses - they vary a lot, and mine is but one.

More later. For now, on the hot tub: My tub, which I no longer use and actually never have used, or have any H2O in after I figured out what an energy hog it is, had an estimated heat loss of ~ 35 - 40 BTU/(hr.*ft^2*deg.F.) It is ~ 7' X 7' X ~ 3 ft. deep w/~ R10 foam insulation all around and an R6 cover. I estimated the covered hourly heat loss from temp. measurements taken before I emptied it. If still in use and if the water was to be maintained at, say 105 F., and my average annual outside ambient Temp. is 62.9 F., which is the average hourly temp. at my house since moving in ~ 9 yrs. ago, the total annual heat loss would be very ~ [37.5*24*(105-62.9)* 365.25]/3412 ~ = 4,056 kWh/yr. if "on" 24/7/365, and if the heat is supplied via electric resistance heating. My current total annual usage is ~ 6,800-7,200 kWh/yr. To me, the hot tub is an energy hog. I swim at LA fitness and soak in their hot tub, but, again, opinions vary.

Real SWAG to generate that much electricity w/ east or west facing panels in Fresno will require about 3kW of PV panels, or, at your ~ $2.50/Watt, ~ $7,500 before tax credit.

Or, in terms of what the hot tub might add in terms of annual electric bill increase: At an average per kWh cost of, say, $0.28/kWh is used, the hot tub would add $0.28*4,056 = ~ $1,135 to my electric bill. Your results will be different.

[dcchapman7]

Wow, that's more than double what I anticipated on hot tub power usage... okay, will consider. Of the two estimates, do you think the Hanwa system with optimizers is the better deal? And do you think it would be worth it to install on the patio cover for reasons mentioned above or go for the east facing roof?

[J.P.M.]

Wow, that's more than double what I anticipated on hot tub power usage... okay, will consider. Of the two estimates, do you think the Hanwa system with optimizers is the better deal? And do you think it would be worth it to install on the patio cover for reasons mentioned above or go for the east facing roof?

On panel quality, I believe above some basic level of quality, most panels are now a commodity like tank type water heaters and garage door openers. Most of this business is not rocket science. I'd spend more time making sure of the quality of the vendor I chose than which panel.

On hot tub usage, your losses will vary. I note that I extrapolated from 24/7/365 continuous run time. The actual loss I measured from temp. drop was higher than a calc of losses from published R values would lead, which mostly jives with my somewhat limited experience at measuring heat losses in residential type systems.

[dcchapman7]

Got it, do you think it would be worth it to install on the patio cover for reasons mentioned above or go for the east facing roof?

[J.P.M.]

Got it, do you think it would be worth it to install on the patio cover for reasons mentioned above or go for the east facing roof?

I don't know enough about your particular application or situation to have an intelligent opinion about it, but I'd be very careful about putting much of anything on a patio cover, especially tilted panels, and, for a lot of reasons, I'd not put any panels horizontal most anywhere. Those two things and probably lots of others make the patio cover location a hard sell for me.

[solar pete]

It would have to be a very well built patio to even consider mounting there (but it could be) but I think tilt frames up there would be a bad idea, think of the wind sock that will be up on your patio

[cebury]

I shouldn't have replied in the other thread, but my comments are there.

[J.P.M.]

Mods: Can these threads be combined ?

Thanx.

[dcchapman7]

Here are shots of the west facing patio cover just to give an idea of what it's like...if it were you would you still put the 13 panels on the east facing roof?

[dcchapman7]

I ran it through PV watts - for installing the 13 panels on the west facing patio cover with 10 degree tilt and 20% losses,output is 5738 watts, an installing them on the east facing roof with 22 degree tilt and 20% losses is 5590 watts... thoughts?

[Mike90250]

I ran it through PV watts - for installing the 13 panels on the west facing patio cover with 10 degree tilt and 20% losses,output is 5738 watts, an installing them on the east facing roof with 22 degree tilt and 20% losses is 5590 watts... thoughts?

What was the annual harvest (not the daily) ? That's the deciding factor. If they are close, then go with the easiest, which I suspect is the patio

[J.P.M.]

I ran it through PV watts - for installing the 13 panels on the west facing patio cover with 10 degree tilt and 20% losses,output is 5738 watts, an installing them on the east facing roof with 22 degree tilt and 20% losses is 5590 watts... thoughts?

In addition to my why the 20 % losses, and going back to your original post with respect to T.O.U. rates and orientation, another question I'd have is : How much of a difference in annual revenue will the two different orientations produce ? My guess is under current and probably (at least for a while) T.O.U. tariffs, that the west orientation will produce more annual revenue (or off set more of an annual bill, same thing). You can get the hourly output estimates from PVWatts, but you'll need information on what your POCO charges for each of 8,760 hours for the year. Getting that info sounds like a daunting task and a PITA, but while it's a pain, it'll be necessary if you want a better estimate. On the other hand, if it takes, say, 4 hours and saves a couple hundred $$/yr., it might be worth it. Your money, your choice. Whatever you decide, it'll still need to account for shading.