Solar Panel System Size

[Bluedietcoke]

New to solar. Was quoted from Tesla a 6.8 kw system (16 panels) all on South facing side of roof. I live in Las Vegas so we get sun quite a bit. They say that should produce around 12,514 kw/y. Does that sound about right? When I look up 6.8 kw system solar systems online everything I see suggests that size system produces less than that. Just want to make sure everything sounds correct before moving forward. Unfortunately in Nevada we can only do up to 100% of used yearly energy so just making sure that size sounds correct. I use about 12,600 kw per year based on last year.

Thanks for the help!

 

[RichardCullip]

Sounds about right to me for a south facing orientation with little to no shade in Las Vegas

 

[CWhite]

I have a 7.8 kw system (with 6.7 inverter) in Portland OR and I get about 10,000 kWh a year so it seems logical for you to get 12,000

 

[jjrandorin]

New to solar. Was quoted from Tesla a 6.8 kw system (16 panels) all on South facing side of roof. I live in Las Vegas so we get sun quite a bit. They say that should produce around 12,514 kw/y. Does that sound about right? When I look up 6.8 kw system solar systems online everything I see suggests that size system produces less than that. Just want to make sure everything sounds correct before moving forward. Unfortunately in Nevada we can only do up to 100% of used yearly energy so just making sure that size sounds correct. I use about 12,600 kw per year based on last year.

Thanks for the help!

You should try modeling it yourself at pvwatts.

PVWatts

Estimates the energy production and cost of energy of grid-connected photovoltaic (PV) energy systems throughout the world. It allows homeowners, small building owners, installers and manufacturers to easily develop estimates of the performance of potential PV installations

pvwatts.nrel.gov

 

[Bluedietcoke]

Thanks for the help. Is there anything else I should be requesting / upgrading with Tesla. Not sure that there are many options to begin with. I figured not to get a power wall. Power outages are very rare in Vegas. Anything I’m missing though?

 

[jjrandorin]

Thanks for the help. Is there anything else I should be requesting / upgrading with Tesla. Not sure that there are many options to begin with. I figured not to get a power wall. Power outages are very rare in Vegas. Anything I’m missing though?

I dont know what Nevada's NEM (net energy metering) rules are, but you want to take a very hard look at that when deciding if you want a powerwall or not. Having a battery allows you to consume your own solar when your system isnt generating, thereby avoiding peak energy charges in Time of use billing plans.

If you will be forced into a time of use billing plan in nevada, you need to take a look at whether having a battery makes sense from that perspective. You also need to take a look at what your projected Increased usage will be, and try to get as much solar as they will let you put on the roof (not what you use right now).

 

[Bluedietcoke]

I dont know what Nevada's NEM (net energy metering) rules are, but you want to take a very hard look at that when deciding if you want a powerwall or not. Having a battery allows you to consume your own solar when your system isnt generating, thereby avoiding peak energy charges in Time of use billing plans.

If you will be forced into a time of use billing plan in nevada, you need to take a look at whether having a battery makes sense from that perspective. You also need to take a look at what your projected Increased usage will be, and try to get as much solar as they will let you put on the roof (not what you use right now).

I’m not sure how to determine if a battery helps honestly. Regarding size, from my understanding Nevada won’t allow a system that produces more than what you used the previous year unfortunately.

 

[jjrandorin]

I’m not sure how to determine if a battery helps honestly. Regarding size, from my understanding Nevada won’t allow a system that produces more than what you used the previous year unfortunately.

If having solar is going to force you onto a time of use rate, where certain parts of the day are a lot more expensive than other parts, expect the solar to be credited at. low rates, while much of your energy usage is during peak rates.

This is something you need to determine whether you want now (either batteries, or more solar). Its NOT cheaper to do it later, and you wont be adding onto your solar by having someone put some additional panels up later either. Any new solar will be a brand new install (2nd system), and adding batteries after the fact if you want to, will be more expensive (generally a lot more) than doing it now.

 

[Bluedietcoke]

If having solar is going to force you onto a time of use rate, where certain parts of the day are a lot more expensive than other parts, expect the solar to be credited at. low rates, while much of your energy usage is during peak rates.

This is something you need to determine whether you want now (either batteries, or more solar). Its NOT cheaper to do it later, and you wont be adding onto your solar by having someone put some additional panels up later either. Any new solar will be a brand new install (2nd system), and adding batteries after the fact if you want to, will be more expensive (generally a lot more) than doing it now.

That makes sense. I am currently on a time of us plan due to having a Tesla. Made it cheaper at night. As far as size / amount of panels, it’s seems like I am limited. I would like to do more, but I guess Nevada has a cap based on previous year usage.

 

[dho112]

I am in California in the SF East Bay area. South facing 9.6Kw system 24 panels. It's probably moderately less sun in a year than in Las Vegas, and I got 18.02Mw production/year. So since you have 66% of the panels I do 12Mw a year is the direct translation, but since you get more sun over there for longer I would guess you'll probably see 13-14Mw of production/year unless you have objects that shade your panels during a portion of the day... (palm trees? A giant Saguaro cactus next to your house LoL!)

 

[oceaheav]

You can do whatever you want. They just assume 100% of last year's usage because that's the most common scenario.

 

[holeydonut]

I am in California in the SF East Bay area. South facing 9.6Kw system 24 panels. It's probably moderately less sun in a year than in Las Vegas, and I got 18.02Mw production/year. So since you have 66% of the panels I do 12Mw a year is the direct translation, but since you get more sun over there for longer I would guess you'll probably see 13-14Mw of production/year unless you have objects that shade your panels during a portion of the day... (palm trees? A giant Saguaro cactus next to your house LoL!)

How the… I got 23 panels in East Bay and I only get 13 MWh.

This is by far the saddest chart of the day

 

[FurryOne]

That makes sense. I am currently on a time of us plan due to having a Tesla. Made it cheaper at night. As far as size / amount of panels, it’s seems like I am limited. I would like to do more, but I guess Nevada has a cap based on previous year usage.

Here's something to check into since you're on VTOU - my Utility will not allow you to use credits earned in one rate period to offset usage during another period, so if you don't have batteries, then the power you use during night rate will be billed to you even though you generate credit during the day. Having batteries allows you to use stored solar to coast through the night on solar you generated during the day, avoiding night charges. My Utility also has a "super peak" of 2-7pm from Jun-Sep, and any excess credit I generate becomes stranded & unusable after Sep until my Anniversary in Mar, when they pay me at a lower rate. Your Utility may do things differently, but you should find out before. ( Since I had 686kWh stranded in the Super Peak rate period last year, I intend to charge my Tesla to burn up the credits in that rate period before they become stranded in Sep.)

 

[oceaheav]

Credits don't expire in Nevada.

 

[dho112]

How the… I got 23 panels in East Bay and I only get 13 MWh.

This is by far the saddest chart of the day ent

I have no idea why you wouldn’t at least be close to my numbers with your configuration…

Are all your panels south facing? I know that many of my friends have panel arrays on differ sections of their roofs with only most of them south facing.

I have vaulted ceilings which translate to a low pitch roof which in turn sets my panels at a very perpendicular angle to the sun for a larger portion of the year. I never realized before how much it helps to have the panels directly facing the sun (azimuth as well as elevation facing)

I’m inland Eastbay (Dublin) and its typical that people in the Eastbay, closer to SF will be in overcast while I’m in bright sunshine even though we’re both “Eastbay” It’s also typical that during overcast, the layer is much thicker the closer you get to SF and the coast. I have a friend with the same system as me but much closer to SF on the other side of the hills and he’ll be producing 2-3kw, at the same time I’m producing 5-6 when we’re both under solid overcast.

Do you have any shade at all cast on your panels during the day/season? I have clear view of the sun’s track, winter to summer for the entire day. Below is a typical clear day in early spring. Later in May-July production numbers will be closer to almost 70kw/day. You can see my 7.6Kw inverter clipping my production , but my excess solar panels help me more in the winter than if I sized to avoid spring/summer clipping. This is also my production this month even though its been cloudier in this April compared to last.

In the end, there seems to be an infinite number of mysterious and not so mysterious reasons why two systems of the same config will vary in their numbers.

Are your numbers inflated to the same degree as mine were from Tesla? They told me based on my config, I would average 14.5 Kwh/year and I did 18. Was your delta about the sane given what they predicted for you?

 

[holeydonut]

Yeah, my panels face southeast... no shading though.

It's probably a combination of my panels being 345 watt, the azimuth, me using micros that probably get soaked in heat on a tile roof (even though I have standoffs!), and all these blade disconnects emitting heat/buzzing.

Anyway, need moar solarrrrr hah. Can't get enough (unless you're h2ofun).

 

[rzn89]

I am in NY 15 miles South of NYC. I am getting a 6.8 kw system w/ 17 panels, south facing panels no shade issues. They estimate 5,913 kwh per year, seems from reddit forum most people in the NY/NJ area are producing more that the Tesla estimate. I have my install scheduled for Friday. We have net metering here, and the credits get banked and roll over for 20 years. Starting January they are eliminating it or you will loose 50% of over production and excess will expire after 1 year. Your estimate would seem accurate based on mine. I was able to petition for larger system since I have a Tesla MYP. My home is off the charts efficient as it 100% foamed and 2x6 framing built in 2019, so the elec company didn't push back since my 2year avg was 337 kwh for a 3300 sq ft home.