Discuss solar panels for home electricity use

[brainhulk]

I'm seeing a few people I know hopping on the solar wagon. What do you guys think about it? How durable are the panels against the elements? Are they efficient enough now that they are worth the startup cost? What does the pipeline look like technology wise, such that if I buy now - will the panels be obsolete in the near future...

btw, my electric bill ranges from a high ~$120-$140 in the summer ac use months to about $70-$100 in others

 

[Raghu]

Thanks for the thread. Similar questions from me, but slight different scenario though. Im hoping theres someone out there with the experience.

1) Can I do it without the electricity company knowing? Assume that my consumption will always be more than the solar panels can provide.
2) How good is the DIY scene? Whats a good starting point for building your own panel+electronics? Any academic resources on design/theory of the electronic subsystems?

TIA.

 

[Bignate603]

Thanks for the thread. Similar questions from me, but slight different scenario though. Im hoping theres someone out there with the experience.

1) Can I do it without the electricity company knowing? Assume that my consumption will always be more than the solar panels can provide.
2) How good is the DIY scene? Whats a good starting point for building your own panel+electronics? Any academic resources on design/theory of the electronic subsystems?

TIA.

1) You can do it without reporting it to your power company, but why? Installing stuff like this usually only makes financial sense when you can get the rebates and things from your power company and the government.
2) Don't try to make your own system. You'll end up with a system that doesn't work as well, won't really be any cheaper (if you do it right) and it might be harder to get your rebate.

 

[LurkerPrime]

I've looked into doing this a few times in the past. Its actually cost effective if I do the install myself, however I'm pretty lazy and its much easier (although more expensive) to write a check to the electric company every month.

Anyway. The big part of the equation is where do you live and the sun exposure at that location. You can check out the solar radiation maps here:
http://rredc.nrel.gov/solar/old_data/nsrdb/1961-1990/redbook/atlas/
You will most likely install flat plates tilted south at latitude so click that option, however other options exists if you install a sun tracker, etc. If your annual is around 5-7 kwH/m^2/day then you are in a pretty good spot for solar. Obviously the higher the better.

The next thing to think about is your state and federal tax rebates. Most states have generous rebates, however in my state its a non-refundable tax rebate that I can carry over for 5 years. So in order to get the full rebate my state tax liability will have to be equal to or greater than the rebate amount over 5 years. That also means I will have to pay the costs upfront and get reinbursed over that 5 year period (less than 5 years if I have a high state tax liability).

Another bonus is if you live in a net-metering state. In those states the utility is forced to buy your excess electricity at a predetermined rate. In my state I could actually end up making money in the summer months by selling my excess electricity.

The downside is these systems are expensive and require the entire amount upfront due to how the rebates work. They will also require maintenance and will require a fair amount of realestate in your backyard unless you have a house with a south facing roof angled at your latitude.

 

[FoBoT]

not cost effective
especially if the gubberment has to subsidize it
/thread

 

[DominionSeraph]

not cost effective
especially if the gubberment has to subsidize it

Wrong and non sequitur.

 

[Analog]

Solar Shingles FTW.

Built right here where I live.

 

[DesiPower]

Its not cost effective, it will takes years to make up for the cost, plus the maintenance. If you have a battery grid where the power will be stored for night use, its even more expensive.

You will need permit as you will be taping into the main electrical system of your house that connects to the grid. If you use Pros to install it, they will take care of the permit, If I am not mistaken, DYI needs inspection.

If you want to do the right thing, you can buy alternate energy, my power company lets me buy a part of my electricity from wind. If you want to have it for rolling blackouts or stuff like that then its definitely worth it but then you need battery array and that expensive.

my 2 cents

 

[Golgatha]

Wrong and non sequitur.

I'd argue it is much more cost effective to install solar en masse at a centralized location, rather than trying to install and maintain installations at individual residences.

 

[DominionSeraph]

I'd argue it is much more cost effective to install solar en masse at a centralized location, rather than trying to install and maintain installations at individual residences.

And mass transit is more efficient than hybrids or electric POV's. But people seem to prefer individual contributions.

 

[bobdole369]

I've looked into solar as a possibility for vehicle installation (say on a van or small RV). It makes sense in that application as you'll normally be paying a premium for your electricity. It doesn't make sense if you actually use a lot of electricity though.

A 230W (rated) panel is roughly 3.5' x 6.5' and you need about 6 inches under it. If you take your van and install 4 of these on the roof you have a rated power input of 920W. The actual power output you can "count on" is about half that - so 450W of "dependable" power 10-14 hours a day.

A house is obviously on the next level - you'll have say a 20' x 20' field or area on the roof, so you could fit - oh about 18 of these, giving you 1.8kw of dependable power 10-14 hours a day.

Cost of electricity where I live is $0.08 - $0.12 per kwh. So lets say you get 2kw per hour, average that over the course of the day to make the math easier - 1kw for a 24 hour period or 24kwh in a day.

Having this installed will save you $2.40 per day in electricity.

The cost of each panel wholesale is $360. x 18 is $6500 (rounded). Double that for installation. Also you'll need something like 12 8D batteries in order to buffer and store the energy, and at least a 2kw inverter. The cost of each battery is $400 x 12 = $4800 (so you can store 24kwh at a rate that won't kill the batteries). The cost of a 2kw grid-tie sine wave inverter: roughly $1300.

$6500 panels
$6500 installation
$4800 batteries
$1300 inverter

This doesn't cover monitoring, transfer, metering, etc = $19,200
This also doesn't cover any rebates or tax credits you might get.

So that $2.40 each day you save will take you 22 years to make up the cost of the system.

 

[rsutoratosu]

I saw this a couple of years ago, they were introducing it... is it widely available and adopted now ? it is pretty neat

Solar Shingles FTW.

Built right here where I live.

 

[rsutoratosu]

So that $2.40 each day you save will take you 22 years to make up the cost of the system.

I asked my cousin about solar panel as he's an architect in nyc and teaches at columbia, like ted mosby, lol. Anyway yeah he confirmed, in nyc, you will almost never which is like 22 years or more, break even or come close.

Thats why they dont have a lot of house on panels with all the credits, etc, i almost never seen one there in my life.

I see a lot in Hawaii, almost all the houses has them

 

[LurkerPrime]

I'm pretty sure all the people saying it isn't cost effective have done about 0 analysis. If you do the install yourself (allows for a larger system) and take advantage of state and federal subsidies you only end up paying 35% of the actual cost (may be more or less depending on your state). Also taking into account net-metering from your utility and they act as a "battery" since your meter runs backwards during the day when the suns out and then you use your "stored" energy at night. Then if you have a stored balance at the end of the month the utility writes you a check.

In my analysis it would take about 6.5-7.5 years to pay off the cost of a solar system using the money that I would normally send to my utility for electricity (thats assuming prices didn't go up, and we all know that NEVER happens). After that point your initial investment is paid for and your electricity is essentially free.

Most solar panels have a 20-30 year warranty and are expected to lose 10-15% of thier generating capacity over that time frame. So you'll enjoy your free electricity for at least another 14-24 years after they are paid off, assuming you spend the time to clean and maintain them.

If I expected to live in my current house forever, I would have done this already. Maintenance, installation and dropping 30K however have definately been factors in not actually following through.

 

[Griffinhart]

I know a bit about this. I worked for a company that produced PV and Thermal Solar products. (Schott Solar).

The Up Front costs on solar is huge. Depending on the materials and the wattage of the panel, expect $500 to $900 per panel, which average 180 to 200w each. Then you need the mounting hardware, cabling, inverters, etc. Then there is the labor. It's not exactly a do-it-yourself, sort of project for the vast majority of people.

Depending on location and power requirements, The average solar installation costs $30K to $75K. The further north you live, the more panels you will need, as in places like Seattle, Boston, Pittsburg, there is only about 3 hours a day where you will be producing electricity.

It is possible to get an anual net cost of electricity of zero when you average summer(producing excess) and winter (producing less) months. The Payback time for solar installations are in the 18 to 25 year range. These will also have maintanence costs too. Panels, mounts, wiring, inverters will occasionally need to be replaced.

If you're really into the idea of solar, There is also the option of companies like SolarCity. They install the system and you pay them as you would your electric company. I'm not terribly familiar with them, but I hear commercials on the radio from them a lot and it seems like something to at least check out if someone is considering solar.

 

[skyking]

I have a different goal regarding solar. I only want enough output to charge a battery bank for personal use. Some day We'll build a dream home with DC LED lighting, and the solar would be built to match that need. When the power goes out (as it does often in big tree country), having good lighting is the biggest comfort.
Current home LED lights all covert AC to DC. this adds quite a bit to per-unit costs. Using DC, I can build my own fixtures at reduced costs.
I'd have indirect lighting built into the architecture, similar to this.
http://www.phantomlighting.com/cove-lighting.htm

 

[bobdole369]

I'm pretty sure all the people saying it isn't cost effective have done about 0 analysis. If you do the install yourself (allows for a larger system) and take advantage of state and federal subsidies you only end up paying 35% of the actual cost (may be more or less depending on your state). Also taking into account net-metering from your utility and they act as a "battery" since your meter runs backwards during the day when the suns out and then you use your "stored" energy at night. Then if you have a stored balance at the end of the month the utility writes you a check.

In my analysis it would take about 6.5-7.5 years to pay off the cost of a solar system using the money that I would normally send to my utility for electricity (thats assuming prices didn't go up, and we all know that NEVER happens). After that point your initial investment is paid for and your electricity is essentially free.

Most solar panels have a 20-30 year warranty and are expected to lose 10-15% of thier generating capacity over that time frame. So you'll enjoy your free electricity for at least another 14-24 years after they are paid off, assuming you spend the time to clean and maintain them.

If I expected to live in my current house forever, I would have done this already. Maintenance, installation and dropping 30K however have definately been factors in not actually following through.

Yeah my analysis is essentially "middle-of-the-road" and depends wildly on where you live. It assumes 50% rated power actually generated and doesn't figure any credits. It also doesn't figure the replacement cost on battery banks - which normally happen every 5 years with lead-acids.

Were I to own my home, and live where I do now - (sunny south FL), or in the SW desert or Texas, I would do it too. Anywhere north of the Mason-Dixon line ought to forget about it and look into cost savings from geothermal or wind.

 

[LurkerPrime]

I've looked into solar as a possibility for vehicle installation (say on a van or small RV). It makes sense in that application as you'll normally be paying a premium for your electricity. It doesn't make sense if you actually use a lot of electricity though.

A 230W (rated) panel is roughly 3.5' x 6.5' and you need about 6 inches under it. If you take your van and install 4 of these on the roof you have a rated power input of 920W. The actual power output you can "count on" is about half that - so 450W of "dependable" power 10-14 hours a day.

A house is obviously on the next level - you'll have say a 20' x 20' field or area on the roof, so you could fit - oh about 18 of these, giving you 1.8kw of dependable power 10-14 hours a day.

Cost of electricity where I live is $0.08 - $0.12 per kwh. So lets say you get 2kw per hour, average that over the course of the day to make the math easier - 1kw for a 24 hour period or 24kwh in a day.

Having this installed will save you $2.40 per day in electricity.

The cost of each panel wholesale is $360. x 18 is $6500 (rounded). Double that for installation. Also you'll need something like 12 8D batteries in order to buffer and store the energy, and at least a 2kw inverter. The cost of each battery is $400 x 12 = $4800 (so you can store 24kwh at a rate that won't kill the batteries). The cost of a 2kw grid-tie sine wave inverter: roughly $1300.

$6500 panels
$6500 installation
$4800 batteries
$1300 inverter

This doesn't cover monitoring, transfer, metering, etc = $19,200
This also doesn't cover any rebates or tax credits you might get.

So that $2.40 each day you save will take you 22 years to make up the cost of the system.

With utility net-metering you don't need batteries. You can also do the installation yourself. Thats $11,300 in savings right there. So your at $7,800 before rebates. If your state has a good rebate combinable with federal rebates you'll pay about 35% of that, so $2,730. Using your $2.40 a day in savings it'll take slightly over 3 years to recoup your investment. Afterwhich you will save 876 dollars a year (annual return of 32% on your 2,730 investment).

You see alot of systems in Florida and Hawaii due to the much higher solar radiation recieved. Check out the maps I linked in one of my earlier posts. Anything north of Georgia and not in the desert get shitty radiation amounts. This will directly effect the amount of energy generated annually, which will in turn significantly increase the time to recoup your initial investment.

 

[bobdole369]

With utility net-metering you don't need batteries. You can also do the installation yourself. Thats $11,300 in savings right there. So your at $7,800 before rebates. If your state has a good rebate combinable with federal rebates you'll pay about 35% of that, so $2,730. Using your $2.40 a day in savings it'll take slightly over 3 years to recoup your investment. Afterwhich you will save 876 dollars a year (annual return of 32% on your 2,730 investment).

You see alot of systems in Florida and Hawaii due to the much higher solar radiation recieved. Check out the maps I linked in one of my earlier posts. Anything north of Georgia and not in the desert get shitty radiation amounts. This will directly effect the amount of energy generated annually, which will in turn significantly increase the time to recoup your initial investment.

If I were to do something like this - it would be with the secondary goal of being completely self-sufficient. That is - in the case of disaster/war/deciding to be a hermit, I could simply unplug from the utility and have enough power for lighting and basic needs. Therefore I wouldn't consider using a battery-free solution. Doing the install myself is a no-brainer - having done similar stuff on boats, just a matter of materials and engineering.

 

[Griffinhart]

If you had direct sunlight 24 hours a day, it would take roughly 100 square feet to general 1kw of power, which should be enough for the average home. But, averaging annual sunlight due to cloud cover and seasons, Northern states can only reliabily expect an average of 3 hours of solar power generation per day. States like California and Florida average 5 to 6 hours. About the best you can get are in deserts that get the most sun possible like in Arizona which gets an average of 7 hours of direct sun per day.

No one hits the break even point in 3 years. It's generally 18+ years. Most in the industry estimate the payback point between 20 and 25 years and that is with subsidies.

 

[the DRIZZLE]

I've looked into solar as a possibility for vehicle installation (say on a van or small RV). It makes sense in that application as you'll normally be paying a premium for your electricity. It doesn't make sense if you actually use a lot of electricity though.

A 230W (rated) panel is roughly 3.5' x 6.5' and you need about 6 inches under it. If you take your van and install 4 of these on the roof you have a rated power input of 920W. The actual power output you can "count on" is about half that - so 450W of "dependable" power 10-14 hours a day.

A house is obviously on the next level - you'll have say a 20' x 20' field or area on the roof, so you could fit - oh about 18 of these, giving you 1.8kw of dependable power 10-14 hours a day.

Cost of electricity where I live is $0.08 - $0.12 per kwh. So lets say you get 2kw per hour, average that over the course of the day to make the math easier - 1kw for a 24 hour period or 24kwh in a day.

Having this installed will save you $2.40 per day in electricity.

The cost of each panel wholesale is $360. x 18 is $6500 (rounded). Double that for installation. Also you'll need something like 12 8D batteries in order to buffer and store the energy, and at least a 2kw inverter. The cost of each battery is $400 x 12 = $4800 (so you can store 24kwh at a rate that won't kill the batteries). The cost of a 2kw grid-tie sine wave inverter: roughly $1300.

$6500 panels
$6500 installation
$4800 batteries
$1300 inverter

This doesn't cover monitoring, transfer, metering, etc = $19,200
This also doesn't cover any rebates or tax credits you might get.

So that $2.40 each day you save will take you 22 years to make up the cost of the system.

There is a free program from the NREL called PVwatts, it can give you much more accurate information about the amount of production you will get per year given your location, type of panels, angles, shading etc. I recommend anyone use it as part of their financial analysis for residential scale solar. Also the Federal and State incentives really make or break solar. I think the 30% Federal refundable tax credit just expired.

 

[Griffinhart]

There is a free program from the NREL called PVwatts, it can give you much more accurate information about the amount of production you will get per year given your location, type of panels, angles, shading etc. I recommend anyone use it as part of their financial analysis for residential scale solar. Also the Federal and State incentives really make or break solar. I think the 30% Federal refundable tax credit just expired.

Wow, great calculator there. In the Boston area (where I live), with a 30% subsidy, it would take more than 30 years to hit the break even point.

 

[allenk09]

When the sun goes out, you'll be screwed.

 

[ShawnD1]

Solar Shingles FTW.

Built right here where I live.

Are these worth getting? On one hand, you get free energy from the sun. On the other hand... black shingles absorb a lot of heat. That's actually the point of solar panels - they absorb light. Wouldn't that theoretically heat the house so you need to run the air conditioner harder?


If you're too cheap for solar, try painting your roof white or some kind of shiny metalic. Maybe put tin foil on the roof. That way you're protected against heat and aliens.

 

[bobdole369]

Are these worth getting? On one hand, you get free energy from the sun. On the other hand... black shingles absorb a lot of heat. That's actually the point of solar panels - they absorb light. Wouldn't that theoretically heat the house so you need to run the air conditioner harder?

I would use an insulator under the sheathing or ramp up the attic ventilation. COuld even do some neat stuff like cycle hot water tank water under that.