First timer - Thinking about 30,000 kwh ish system!

[SoloCon]

Based on your numbers...

14205 kWh / 264 days = 53.8 kWh/day
53.8 kWh/day * 365 days/year = 19640 kWh/year
53.8 kWh/day / 24 h/day = 2.24 kW

So your yearly consumption is about 20000 kWh per year and your current average load is about 2.25 kW.

Assuming you get on average around 8 hours of full sunlight a day every day of the year, you will need a solar array of 3 * 2.25 kW = 6.75 kW minimum to cover your current usage. Make that 8 kW just to be sure (20 panels).

An average mini split uses 600 watts/hour. Two of them will add 1.2 kW/h.

An EV requires huge power in the range of 50 - 100 kW per full charge (real world is around 75 kW maximum). Assuming the maximum and fully charging every day, you will require 100 kW in 8 hours of full sunlight. That's 12.5 kW per hour. So you would need 8 kW + 1.2 kW + 12.5 kW = 22 kW of solar power every day to run everything. The would require 55 x 400 watt panels or 54 x 410 panels.

Your number of panels is in the same ball park, but it seems like a large system. The EV would require more than half the system, and the size and complexity is high for a first time DIY system. Without the EV you would be down in the 10 kW range which still seems a little large for a 2500 square foot house. Do you plan to install 55 panels on your roof? Is there room?

You also need to work out the deal with micro, grid-tie, string, and hybrid inverters. Since you haven't provide information on how you plan to put it all together, I suspect that you don't know yet, and may not understand the purpose and differences between them. You need to decide how you are going to connect the PV system to the grid or the inverter. I think it might be good to consider a string inverter configuration unless you have shading or angle issues on your roof.

Batteries are rated in amp hours. So you need to convert your power needs from kWh to amp hours to determine how large of a system you will need and how much it will cost. Lead acid batteries typically range from 200 - 400 amp hours each @ 12VDC. Lithium (LiFePO4) typically range from 100 - 300 Ah @ 3.65VDC. Your inverter will probably require 48VDC. Assuming 12V lead acid batteries (50% discharge), to get near 40 kWh of usable power, you will need 2 x 4 x 200Ah x 4 = 32 deep cycle batteries. Lithium will require four times the number of cells, so a total of 128 cells. Both would provide 800 Ah @ 48VDC. That is a fairly large battery. It would run your house for a few hours. Although it is fairly large, you have to remember that the EV needs 50 - 80 kW per charge, so a 40 kWh battery won't be able to fully charge the EV every day. If you really are planning to charge an EV with the system, you will need to feed the grid all day long and then use the grid to charge the EV. You will still pay for electricity. If you use the battery, you won't be able to store enough to do a full charge, and you will wear the battery out.

Sol-Ark is probably the most expensive option out there. Maybe I would buy them if there price wasn't three times the alternative. You should look at alternatives unless you have plenty of money. Maybe consider scaling back the system for now.

Your month of August number comes out to an average load of 6.62 kW all day and night for 30 days straight. That is 3 times as high as your current rate of consumption. You must have had central air running non stop for a month in 115 degree temperature.

Before you buy anything you need to do your own calculations to make sure its all correct.

Thank you for the well thought out response. While I understand my new home is using less power (about half?) I would like to build the solar array for future use as well, hence the larger system.

Based on your numbers, (I still need to validate on my end), it seems the size system is a good match?

 

[SoloCon]

Plan for $60-80K if you DIY. As mentioned above, start with the highest efficiency equipment/appliances that you can afford. 20 SEER HVAC or higher and a HP water heater are top priority. They are the two largest consumers on our all-electric homes.

Thank you! This was my approach when building the new house. It was built in 2021, everything new. Used 2x6 with all foam insulation.

• Regarding my AC unit, it's a new XR14 Heat Pump, Trane 5.0 Ton 14 SEER (Model:4TWR4060G1000).
• My water heater is a Rheem Gladiator 50 Gal. Tall 12 Year 5500/5500-Watt Smart Electric Water Heater with Leak Detection and Auto Shutoff (model: xe50t12cs55u1). I keep this in vacation mode 7 of the 12 months as the outside heat heats it up enough.

Both my wife and I work from home and I run a server which is on 24/7, along with my personal computer which is also on 24/7. I've been running a "kill a watt" meter on my server for the past 63 days and it's used 2395 KWh's.

Not really sure what I can cut back on to reduce my power usage. I'm on my personal/work PC ~14 hours a day off and on (run my company from my home). My server is used ~13-16 hours of the day. Just easier to keep it powered on.

 

[SoloCon]

Careful with APS imposed max power size if you are going to be grid tied. I believe they go by your panel amp size. 200 amp service panel you can have a max of 15kw of solar (if you are grid tied). AND there is some other calculation where APS will look at real historical peak demand usage. For example we are frugal now but expect to be more liberal when we have solar - when exploring the grid tie APS they reduced our planned Tesla 15kw to 11kw max because we didn't historically use enough of the high priced power. We are installing non Tesla , non grid tie DIY now (in az and with solarever panels).

I'm debating the grid tie system now as well. Is it worth selling back the power? (Only reason from a grid tied system from my understanding?) While I've not talked with APS, I'm basing this all off my last 3 years of usage with APS.

 

[nscottsdale]

I'm debating the grid tie system now as well. Is it worth selling back the power? (Only reason from a grid tied system from my understanding?) While I've not talked with APS, I'm basing this all off my last 3 years of usage with APS.

the other reason may be "no batteries" or less batteries.

 

[SoloCon]

Depends on your power company’s Net Metering agreement.

For me it is not worth sending any back to grid, as they limit the size of solar system and only give $0.04/kWh that I’d send back.

From my Understand from APS:

It’s important to note that the solar energy your home produces and uses is worth the full-retail rate of electricity. For APS customers, that’s around $0.12 per kWh, but the exact rate will vary

If your solar panels are producing more electricity than your home is using, the excess energy is sent to the grid and is valued at $0.09 per kWh, or about 25% less than the retail rate. That amount is then applied to your utility bill as a credit to offset future energy costs. APS calls this the ‘Resource Comparison Proxy Export Rate’ (RCP rate).

Not sure if doing this (grid tied) is worth it or not? I believe for the next 3-5 years I would be producing about half of what I use, until we build the RV garage and get a EV car. It seems it MIGHT pay for its self? (feedback here would be great)

 

[SoloCon]

Yes. 180kwh - ( 22.5kw x 5.5h ) = 56.25kwh required per day. 82.5kwh back to the grid in 5.5 hours is 15kW per hour. So it is possible on a 100A service. You would need a 1500Ah battery capable of 80% depletion to do that every day. As mentioned above if you can't get back what you put in at 100% then you need even more to break even. Something is really wrong with the proposed consumption in this case. There is no way to put 50 400 watt panels on a 2500 sq ft house roof. There is no reason to need 180kwh of power every day unless you are charging two EVs a day and running AC all the time.

While it seems I can get them on the roof, it probably will not be the best usage to get the use of the solar panels. I'm still looking into this. Here's a few mock (attached)

I can also ground mount of needed. Again, still researching this and looking for some input. Thank you!!

 

[SoloCon]

So what is the Goal?
Are you trying to just cut down the Bill and by how much?
The first thing I would do is go through the house and see what is consuming all of this power. I can see that it is happening in the Summer but a 2500Sq/ft house should not be using this kind of power. Is your Insulation good? Are the AC units fairly new and have the been cleaned?
Something is not adding up and you need to solve that first and then build the system based around a more energy efficient house.

So what is the Goal? - I would like to eliminate my power bill 100% if I can. If not, as close as I can (afford)
Brand new home.

 

[robby]

I would not dump the Grid unless you plan on having a very large generator and a good supply of fuel.
Unless you live on the CA, NV or NM the Weather will give you many days per year when PV production will be very low so Grid tie is really the best and cheapest option.
If your planning on Using two Sol-Ark 15K units then you would not buy Micro Inverters, you would just use strings of regular 400W panels. It's good that you have a professional company helping you because this is not a typical DIY type installation. You are definitely going to need a lot of ground mounted panels to supplement what is on the roof.
If land space is not an issue I would ground mount everything just for more efficiency by optimizing the angling of the panels and the simplicity of servicing them, but that is up to you.

 

[nscottsdale]

Another "hurry up" is the fed tax credit of 26% for the install will fall to 22% next year. I just went through logistics of getting a permit with scottsdale and ordering from various sources .

 

[Hedges]

I live in Oklahoma currently they give dollar to dollar ratio. If I send 82.5 kw and I can use the entire 82.5 kw with in the year

Does utility rate vary with kWh/month, more for heavier usage?
Is there a time of use rate available?

In California, I had higher credits per kWh when exporting more, and higher Noon to 6:00 PM, so got back more kWh off-peak. I was able to bank power for use in winter.
Today, peak rates are 4:00 PM to 9:00 PM, so I can't get back much more than I produce.

Your mileage will vary.

Look for quality; not all panels are the same or maintain power output as well over the years.

Is there a reliable resource to compare panel makes/models

Well that sounds like a heck of a deal! Glad you placed your order and can't wait to see how it all works. That is a very good price, and I should not be surprised but that confirms they get a great deal when they upgrade. I wonder if they went with Trina on the replacement units? Any idea?

diysolarforum.com

SolArk - people do say it works well and is well supported.

I use a low-frequency battery inverter from SMA. Others use Schneider. There are some premium brands if it is in your budget.
At least read up on the offerings of all tier-1 brands before making a selection. Ability to start motors, and features of shaving peak loads may be worthwhile.

https://files.sma.de/downloads/SI6048US-DS-en-28.pdf

 

[SoloCon]

I would not dump the Grid unless you plan on having a very large generator and a good supply of fuel.
Unless you live on the CA, NV or NM the Weather will give you many days per year when PV production will be very low so Grid tie is really the best and cheapest option.
If your planning on Using two Sol-Ark 15K units then you would not buy Micro Inverters, you would just use strings of regular 400W panels. It's good that you have a professional company helping you because this is not a typical DIY type installation. You are definitely going to need a lot of ground mounted panels to supplement what is on the roof.
If land space is not an issue I would ground mount everything just for more efficiency by optimizing the angling of the panels and the simplicity of servicing them, but that is up to you.

Thank you again for the follow up! I have no intentions of cutting grid at all, just not sure if selling (net metering??) setup is worth it??
I live in AZ, plenty of sunshine

I'm looking into ground mounting them now, or as someone else mentioned, build something to mount them to.

 

[SoloCon]

Another "hurry up" is the fed tax credit of 26% for the install will fall to 22% next year. I just went through logistics of getting a permit with scottsdale and ordering from various sources .

Not looking to rush it, 2-3K saving is good, but not good enough to rush this project along.

 

[MattiFin]

From my Understand from APS:

It’s important to note that the solar energy your home produces and uses is worth the full-retail rate of electricity. For APS customers, that’s around $0.12 per kWh, but the exact rate will vary

If your solar panels are producing more electricity than your home is using, the excess energy is sent to the grid and is valued at $0.09 per kWh, or about 25% less than the retail rate. That amount is then applied to your utility bill as a credit to offset future energy costs. APS calls this the ‘Resource Comparison Proxy Export Rate’ (RCP rate).

Not sure if doing this (grid tied) is worth it or not? I believe for the next 3-5 years I would be producing about half of what I use, until we build the RV garage and get a EV car. It seems it MIGHT pay for its self? (feedback here would be great)

Lets say you would use 24000 kWh per year to make nice round number:

You would need about 13 kW panels to match your yearly consumption. (based on JRC tool https://re.jrc.ec.europa.eu/pvg_tools/en/tools.html#PVP )
33*250 = 8250 $ for panels. About 8500 $ for Sol-Ark 15K. Add some bits and pieces and we have $ 18000 system.
On average day you would produce 66 kWh in roughly 5 hours and maybe able to consume 15 kWh of that.
Rest 51kW of it would be sold to powerco at $0.09 per kWh and bought back at 0.12 per kWh, making it effectively $0.03 per kWh
With grid tie system you would be paying 51*365*0.03 = $558 to powerco per year.

without solar panel system you would be paying 24000*0.12= 2880 $/year to powerco.
Grid-tie would save $ 2322 per year and have about 8 year payback at zero interest rate.

Used panels at 50% price and cheaper inverter like 12.5kW Fronius (4200 usd) would sound tempting ..

 

[tcj2001]

Yes. 180kwh - ( 22.5kw x 5.5h ) = 56.25kwh required per day. 82.5kwh back to the grid in 5.5 hours is 15kW per hour. So it is possible on a 100A service. You would need a 1500Ah battery capable of 80% depletion to do that every day. As mentioned above if you can't get back what you put in at 100% then you need even more to break even. Something is really wrong with the proposed consumption in this case. There is no way to put 50 400 watt panels on a 2500 sq ft house roof. There is no reason to need 180kwh of power every day unless you are charging two EVs a day and running AC all the time.

I am confused, say If i buy two EG4-LL batteries, each battery is 48V, 5.12kWh, 100Ah, so I should get 10.24kWh with 200Ah. If I use 80% DoD i can use 8.192kWh max every day from the battery. Now if this is connected to a SolArk-15k inverter which is connected to my load panel 120/240 200A, will i be able to consume 8.192kwh from the battery daily and rest from the grid or Solar Panel, if so how many hours will the battery last, will it last 24hrs or less before it need to be recharged.

 

[Shimmy]

I am confused, say If i buy two EG4-LL batteries, each battery is 48V, 5.12kWh, 100Ah, so I should get 10.24kWh with 200Ah. If I use 80% DoD i can use 8.192kWh max every day from the battery. Now if this is connected to a SolArk-15k inverter which is connected to my load panel 120/240 200A, will i be able to consume 8.192kwh from the battery daily and rest from the grid or Solar Panel, if so how many hours will the battery last, will it last 24hrs or less before it need to be recharged.

Generally speaking you need an absolute minimum of 1kWh per kW of inverter. The EG4-LL also has a "recommended" maximum discharge rate of 30A each, so you would not want to draw more than 3kW average off the battery. Your maximum charging would be limited to ~11kW.

As for how long it will last... do you at least know how many kWh you use per month to be abe to determine average daily load? Would you try to support all your loads, or just a subset? How much solar are you going to have?

 

[tcj2001]

Generally speaking you need an absolute minimum of 1kWh per kW of inverter. The EG4-LL also has a "recommended" maximum discharge rate of 30A each, so you would not want to draw more than 3kW average off the battery. Your maximum charging would be limited to ~11kW.

As for how long it will last... do you at least know how many kWh you use per month to be abe to determine average daily load? Would you try to support all your loads, or just a subset? How much solar are you going to have?

my goal was to see how much kWh i can offset with two batteries rest can come from the grid or solar. I guess based on what you indicated i can only offset 3kWh with two batteries.

 

[niktak11]

Thank you! This was my approach when building the new house. It was built in 2021, everything new. Used 2x6 with all foam insulation.

• Regarding my AC unit, it's a new XR14 Heat Pump, Trane 5.0 Ton 14 SEER (Model:4TWR4060G1000).
• My water heater is a Rheem Gladiator 50 Gal. Tall 12 Year 5500/5500-Watt Smart Electric Water Heater with Leak Detection and Auto Shutoff (model: xe50t12cs55u1). I keep this in vacation mode 7 of the 12 months as the outside heat heats it up enough.

Both my wife and I work from home and I run a server which is on 24/7, along with my personal computer which is also on 24/7. I've been running a "kill a watt" meter on my server for the past 63 days and it's used 2395 KWh's.

Not really sure what I can cut back on to reduce my power usage. I'm on my personal/work PC ~14 hours a day off and on (run my company from my home). My server is used ~13-16 hours of the day. Just easier to keep it powered on.

Is it a rendering server or something? 1600W 24/7 is a lot.

 

[Toyo72]

Is it a rendering server or something? 1600W 24/7 is a lot.

That's what I was thinking, too. Massive power hog of a server, that's as much kWh usage as my entire 2100 sq ft house, other than peak months of July-Aug and Jan-Feb.

 

[adamantium]

Thank you for the well thought out response. While I understand my new home is using less power (about half?) I would like to build the solar array for future use as well, hence the larger system.

Based on your numbers, (I still need to validate on my end), it seems the size system is a good match?

You current usage is about 3/4 of your previous usage. Projecting your usage to the end of the year at your current rate is 19640 kWh/year, but as you said you are going into the hottest time of the year now, so your usage will go up considerably. Your average usage for the past two years is 27700KWh/year, so you are already at 1/2 with about a third of the year yet to go. Assuming 150% of your current average usage for the next 3 months, you will probably really hit around 22,000+kWh this year or 80%.

 

[adamantium]

Based on your numbers, (I still need to validate on my end), it seems the size system is a good match?

Yes the number and size of the panels are a good match, but your power consumption is unusually high, and as I mentioned earlier, you won't be able to fit 50 panels on your roof, at least in a maximal energy producing manner. As others have mentioned too there are limits on what the power company will accept per day and how large the cable, breakers, and panels will need to be to feed your desired amount of power. Based on the pictures you have provided, you will have several strings producing power at different times of the day, and not all of them will be in position to produce at their maximum for the same amount of time. So the calculated power output of all 50 has to be reduced to take that into account. Without the details of your roof angles and panel counts it is impossible to accurately calculate your power output. And finally one big detail to take into account is that the power company is under no obligation to maintain their current price on the power they credit you for. In my state the power company has reduce the pay back rate to 44.6% in winter and 51.6% summer. They were paying 100% just five years ago. So grid tie is a scam that is out of your control. You can't count on it being there as part of your plan.

Since you have the option to ground mount, I would suggest you seriously consider that if you have the money. Ground mounting is more expensive than roof mounting, but the benefits are great. They include being able to clean, inspect, and repair the array from the ground. No falling off the roof or having to remove and reinstall the panels when its time to repair the roof. No ugly panels at various angles and configurations all over your house. Instead you can mount them all in the most optimal direction and at the optimal angle. The problem with ground mounting is the cost of the frame. The array must be able to handle the wind speed and snow loads in your area. Arizona isn't going to have a snow load but you will probably be required to get drawings from an engineer that show the structure meets the required wind speeds in your area and the type of soil you have. You can get premade designs like this online from some of the ground mount manufactures. I designed and built a 7K array for my father's property and was required to use 3 inch diameter galvanized steel pipeline, and 2 foot diameter by 5.5 foot deep footings. That required 9 tons of concrete mix which my 79 year old father and I mixed ourselves. That was absolute overkill, but it is what the city required based on the soil and wind speeds in his area. Despite that though, the total cost of his system was about $20,000 including ground frame, panels, cable, distribution panels, switchs, SMA SunnyBoy and Schneider inverters, and AGM batteries. The price of panels and LiFePO4 batteries has come down considerably since then but the price of everything else has gone up. You might consider buying an inverter brand from China.