Question for the Solar Guru's... 🌞

[dalola]

Is there some kind of a rough conversion for square feet of roof space as it relates to potential energy capture? I've got about 600ft2 of 6/12 south-facing roof on the back of my garage, I'm considering a solar installation up there, primarily to provide power for my Emporium charger, plus any left over to feed into the house/garage. Any thoughts/comments from those who have experience with solar?

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[markboris]

Is there some kind of a rough conversion for square feet of roof space as it relates to potential energy capture? I've got about 600ft2 of 6/12 south-facing roof on the back of my garage, I'm considering a solar installation up there, primarily to provide power for my Emporium charger, plus any left over to feed into the house/garage. Any thoughts/comments from those who have experience with solar?

I have solar panels on both south and west facing roofs on my home. I left all of the calculations up to my friend that worked with me on the install so I would not be able to give you an exact number but..... If you used 400W solar panels, you would be able to fit 22 of them producing 8800W in approximately a 600 sq. ft. space. Naturally they make solar panels in different wattages and sizes. You would need only 19 panels if they were 500W and would produce 9500W, etc. Those are some rough numbers

 

[watchdoc]

use the PVwatts website. a 600 sq ft space should accomodate roughly 10kw of panels. This would be enough to not only charge your EV but to run your entire house with something like a Powerwall 3.

key questions are:

What's your goals?
What's your budget?
Does your utility offer a good net metering or VPP program?
Is your city/county DIY friendly?
Will a DIY install affect your homeowners insurance?

 

[GreaseMonkey]

use the PVwatts website. a 600 sq ft space should accomodate roughly 10kw of panels. This would be enough to not only charge your EV but to run your entire house with something like a Powerwall 3.

key questions are:

What's your goals?
What's your budget?
Does your utility offer a good net metering or VPP program?
Is your city/county DIY friendly?
Will a DIY install affect your homeowners insurance?

And where do you live?

My winter consumption is 11x that of summer at a time when generation is likely way lower. Battery storage allows you to balance day and night, but not season to season.

 

[watchdoc]

And where do you live?

My winter consumption is 11x that of summer at a time when generation is likely way lower. Battery storage allows you to balance day and night, but not season to season.

I live in eastern, NC where we have relatively mild winters (compared to Chicago) but very hot and humid summers.

What type of heating do you have that makes your winter consumption so high? Have you considered a cold climate heat pump or even a solar powered mini split? There are some great video examples of people using this products in very cold climates like Canada.

 

[GreaseMonkey]

I live in eastern, NC where we have relatively mild winters (compared to Chicago) but very hot and humid summers.

What type of heating do you have that makes your winter consumption so high? Have you considered a cold climate heat pump or even a solar powered mini split? There are some great video examples of people using this products in very cold climates like Canada.

My situation is unique given I live in a high rise with floor to ceiling windows and south-east exposure. We use electric baseboard heat and despite managing consumption as good as we can, my typical Jan consumption is 6,000 kWh on a 2,000 sq foot condo.

 

[Tosh]

Your latitude, average cloud cover, and proximity to shade trees all have an affect on the efficiency of a solar array.

I'm at the 45th parallel, no shade trees near the roof, and for 6 months of the year I have great sun exposure. My roof is facing west (36 panels), with a small section (6 more panels) facing east.

The panels are REC 460 watts measuring 68" x 47.5". The 42 panel system is rated to produce up to 19.3 KW. Thus far, I've seen up to 14 KW reported by the Tesla app (2 Powerwalls are also installed). This is enough to run my house and charge the Mach E during the hours between noon and 4pm, drawing no power from the grid. In the winter, not gonna happen! But we still see the PV array producing juice as long as there's no fog, rain, or snow.

This is a 4 year old house with a 200 amp main panel, easy attic access, and the installation was a breeze. Older homes can be more complicated, and therefore expensive, to have solar installed. Our power provider does offer Net Metering and I have permission to export (meaning my excess production goes back into the grid).

 

[watchdoc]

I li

Your latitude, average cloud cover, and proximity to shade trees all have an affect on the efficiency of a solar array.

I'm at the 45th parallel, no shade trees near the roof, and for 6 months of the year I have great sun exposure. My roof is facing west (36 panels), with a small section (6 more panels) facing east.

The panels are REC 460 watts measuring 68" x 47.5". The 42 panel system is rated to produce up to 19.3 KW. Thus far, I've seen up to 14 KW reported by the Tesla app (2 Powerwalls are also installed). This is enough to run my house and charge the Mach E during the hours between noon and 4pm, drawing no power from the grid. In the winter, not gonna happen! But we still see the PV array producing juice as long as there's no fog, rain, or snow.

This is a 4 year old house with a 200 amp main panel, easy attic access, and the installation was a breeze. Older homes can be more complicated, and therefore expensive, to have solar installed. Our power provider does offer Net Metering and I have permission to export (meaning my excess production goes back into the grid).

i literally have half the exact same system as you do. 21 REC Alpha Pure 460s with a single Powerwall 3 and it runs our 2675sq ft house just fine. My array is south west facing and we have a walk around attic as well.

im in eastern nc but we honeymooned in the Willamette valley. Such an amazing area.

 

[dalola]

Thanks all, for the thoughts/info. So it seems very doable.... Next steps are to contact a local solar pro, to get specifics for my area. It's too much out of my wheelhouse for a DIY, other than maybe some of the install. But as far as the spec/set-up, I'll need help there for sure. I'll provide updates as I move along... but this is early early investigation phase..... ? Feel free anyone, to keep adding thoughts/comments/information....

 

[ChrisO]

I have solar panels on both south and west facing roofs on my home. I left all of the calculations up to my friend that worked with me on the install so I would not be able to give you an exact number but..... If you used 400W solar panels, you would be able to fit 22 of them producing 8800W in approximately a 600 sq. ft. space. Naturally they make solar panels in different wattages and sizes. You would need only 19 panels if they were 500W and would produce 9500W, etc. Those are some rough numbers

This is way too simplistic of an answer.

The first thing to realize is almost impossible to get 400W from a 400W solar panel. The 400W rating is under ideal conditions which no one is going to achieve. In the real world there are clouds and maybe shading from trees and the like. What's more this rating is at the 77F. As the temperature changes so does the efficiency. And your location is going to have a lot to do with it. Depending on your latitude and the climate, you will certainly get difference conversion rates. Also, over time the solar panels will degrade. And different quality panels degrade at different rates. So, for the long haul it might worth paying more upfront, to get the better panel.

You would certainly want to start with an estimate for your area and not go with random posts from people with completely different situations.

 

[watchdoc]

Thanks all, for the thoughts/info. So it seems very doable.... Next steps are to contact a local solar pro, to get specifics for my area. It's too much out of my wheelhouse for a DIY, other than maybe some of the install. But as far as the spec/set-up, I'll need help there for sure. I'll provide updates as I move along... but this is early early investigation phase..... ? Feel free anyone, to keep adding thoughts/comments/information....

again, Use sites like PVwatts and Tesla energy to estimate the size of system you need. Beware of solar leasing schemes or financing programs with hidden fees and gotchas. Keep the system simple and user friendly and it will not only pay for itself but will also add value to your home.

 

[dalola]

This is way too simplistic of an answer.

The first thing to realize is almost impossible to get 400W from a 400W solar panel. The 400W rating is under ideal conditions which no one is going to achieve. In the real world there are clouds and maybe shading from trees and the like. What's more this rating is at the 77F. As the temperature changes so does the efficiency. And your location is going to have a lot to do with it. Depending on your latitude and the climate, you will certainly get difference conversion rates. Also, over time the solar panels will degrade. And different quality panels degrade at different rates. So, for the long haul it might worth paying more upfront, to get the better panel.

You would certainly want to start with an estimate for your area and not go with random posts from people with completely different situations.

For sure, and I get all that. I'm just looking for others opinions & experiences for consideration, not as a blueprint for me. I like to evaluate a broad topic, vs just relevant to me info. I know, call me crazy... ?

 

[PaulA]

We have had a 22 panel array since Jan/2020. 12 are 385w and 10 are 310w. We have net metering and were oroducing 152 % of demand before buying the Mach E in July/2022. Our panels face about 30 degrees off due south. We have months in the spring and fall when we generate more than we use. Our furnace and water heater are both gas-fired.

 

[markboris]

This is way too simplistic of an answer.

The first thing to realize is almost impossible to get 400W from a 400W solar panel. The 400W rating is under ideal conditions which no one is going to achieve. In the real world there are clouds and maybe shading from trees and the like. What's more this rating is at the 77F. As the temperature changes so does the efficiency. And your location is going to have a lot to do with it. Depending on your latitude and the climate, you will certainly get difference conversion rates. Also, over time the solar panels will degrade. And different quality panels degrade at different rates. So, for the long haul it might worth paying more upfront, to get the better panel.

You would certainly want to start with an estimate for your area and not go with random posts from people with completely different situations.

Chris, I completely agree with you. As you said there are so many variables however Dave said he was just looking for a "rough conversion" and that is exactly what I gave him.

 

[Tosh]

.... Next steps are to contact a local solar pro, to get specifics for my area. ....

exactly. you want to talk to a local installer with a good reputation, and full certification.

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