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SVreX
SVreX MegaDork
1/17/19 1:38 p.m.

In reply to volvoclearinghouse :

Good info.  Thanks.

 

Robbie
Robbie UltimaDork
1/17/19 2:10 p.m.

How much area will 4.5 kw of panels cover?

Not that I am likely to be up on my roof measuring tonight ...

SVreX
SVreX MegaDork
1/17/19 3:24 p.m.

In reply to Robbie :

I think about 18 SF per panel, times 15 panels. 

volvoclearinghouse
volvoclearinghouse UberDork
1/17/19 9:02 p.m.

Depends.  In MD, for residential structures, they have to allow a 3' wide clear path on each side of the roof and 1.5' at the peak for fire codes (basically so a fireman could walk on the roof).  Each roof half on that building I'm doing is about 450 sq ft of roof (6:12 pitch) minus the square footage of the required walkways.  So probably ~300-350 sq feet.  which works right out to around 20 sq ft per panel, as mentioned.

WonkoTheSane
WonkoTheSane Dork
1/18/19 12:20 p.m.
volvoclearinghouse said:

In reply to SVreX :

The price was a little under 14k, which after the 30% federal tax credit and the $1k MD rebate, brought my out of pocket to 8000 and some, for (15) 300W panels (4.5kW total).  Estimated yearly production given conservative solar energy density for this area, azimuth of the roof, and surrounding trees and whatnot came to about 5700 kW.  

It ain't Wonko's 44 panel solar farm (*grin*) but it'll do for us, for now.  Assuming a linear scale, a system of that size would probably run about 42k, before all the incentives.  

Just as a note, it's been mentioned before, the 30% Fed tax credit is decreasing next year and in a few years will be gone altogether.  

That's pretty cool if that's the case.  My install is about 4 full years old now.  The cost of hardware has come down about ~10% (my setup was 46.5k, I think), while the capacity has gone up 10% (I have 270W vs your 300W)!   Meanwhile electric rates have gone up approximately 10% in that time as well.  Each kWh was about $.162 delivered vs ~$.182 kWh I think it is currently.  

frenchyd
frenchyd UltraDork
1/21/19 11:13 a.m.

In reply to volvoclearinghouse :

With regard wind,  I didn’t give you the full negatives with wind just like you didn’t give me the full negatives with solar.  Up here where we live longer, because frozen keeps pretty well ( big silly grin)  solar won’t repay.  We have months where that rare yellow orb in the sky doesn’t  show for days even weeks. 

Plus the angle of the sun in the winter isn’t optimum for collection.  Not to mention covered with ice and snow doesn’t exactly get the meter spinning.   

However wind has its short comings too.  Some blades are noisy ( not all ) most of the time under good wind generators the noise of the wind covers any  noise the blades make.  We always went to wherever we had a generator in use to give shows and solicit new business. Good ones are pretty quiet.  

Bad news? You have to have an area equal to 105% of the tallest tip of the top blade free from occupied buildings.  To allow for the generator to fall down.  

Weak masts could legally be supported by guy wires  But guy wires told everybody the mast was weak. Good companies used a single pole to hold the generator. Not a lattice assembly. Most cheap generators are gear driven. The Chinese tend towards that but they may not turn in normal light breeze that a direct drive  will.  Direct drive rare earth magnets brushless were the best generators but the Italians can’t make enough rare earth magnets so the price has steadily crept up.  Underneath a good wind generator is a 50 foot deep hole roughly 40’x40’ and depending on which size generator filled with anywhere from 10- 30 feet of rebar re-enforced concrete topped with at least 20 feet of compacted dirt.   In theory a wind generator will withstand 145 mph wind.  Some regularly exceed that. Most wind generators feather the blades at wind speed over 40mph and apply brakes. 

Now with regard birds.  Birds will fly into windows, the sides of barns,  cars, silo’s, and yes on occasion windmills. However the high pressure on the windward side of the blade gives birds one final chance to avoid hitting the blade. Birds are never sucked into windmills, it’s just not how they work. 

Maintenance.  Good ones should be rebuilt at 20 years. Cheap ones will require rebuilding in as little as 7 years.  Plus rebuilding a cheap one is much more complex and expensive than the rare earth brushless ones.  Rebuilding consists of calling a crane with sufficient lifting height and capacity typically 30-50 ton 125’ boom. The whole generator is removed and set on the ground while a technician replaces bearings and other wear items.  Then reinstalled. Costs run between $3000-&10,000  with $10,000 more common with cheap units.  

 

 

volvoclearinghouse
volvoclearinghouse UberDork
1/29/19 10:02 a.m.

WonkoTheSane
WonkoTheSane Dork
1/29/19 2:31 p.m.

yes

TVR Scott
TVR Scott Reader
1/29/19 6:51 p.m.

Just saw this thread.   Didn't read it all but I'll contribute my experiences.

We got a solar system installed in Sept of 2016 and it's been terrific.  Ours is a 5 kWp system, and has 16 panels.  Solar Edge inverter and "load balancers" on each panel.

We had it installed by Namaste Solar here in Denver - a super cool employee-owned company.  Cost was about $15K.  We're not raking in a giant profit on the savings, but our electric meter spins backward almost year round.  Our bill can be $100-150 cheaper in winter time.

Our panels are all on the East roof of the house.  Normally people will tell you to put panels on a West roof, but Namaste has found Colorado houses make better power on the East side since we have lots of afternoon thunderstorms.

Ultimately we'll probably look into some electric cars, and at that point will upsize the system to cover more capacity.  But for now it's perfect for our small city house.

Shoot me any questions or let me know if you want any pics or anything.

youngfg
youngfg New Reader
1/29/19 7:58 p.m.

We have a 22KW DC, 18KW AC system for our house, I installed about 1.5 years ago. It's 64 panels using a ground mounting system. This is enough to zero out our annual electric bill.

Solar System Data Online

I am retired from the local utility company, and I researched solar for 5 years before doing anything. There really are only a few key numbers to look at.

 

Cost per AC watt installed.

Your electric rate.

Your average hours of sun per day.

 

So for my system those numbers are $1.25 per watt.    $0.11 per KWH,    5 hours of sun a day.

18 KW X 5 hours a day X 365 day X .11  = $3613.50 of electricity per year

$22500 for the system

Minus 30% tax credit

Final system cost $15750

System cost $15750 divided by yearly production $3613.50 = 4.35 years to break even

 

A few solar things.

Roof top install can cost more, you need a new roof, you need extra emergency shutdown devices, you will need more engineering and permitting. Roof top is harder to install, harder to work on, and less efficient because of trapped heat.

Ground mounting is better in all of the above things, but you have to have the room for the install.

AC watts is what matters, because that is what you can sell to the utility.  DC watts are what the name plate on the solar panel say, you generally need 25% more DC power from the panels that you have inverter capacity. I have right at 22KW of DC power from the panels, and only occasionally does it max out the 18KW inverters.

Salesmen almost always price DC watts.  DC watts is like gross HP at the crank, AC watts is like wheel HP.

You should be able to get solar installed for about $2.00 per watt. Panels are around $.50 per watt, inverters  about  $.40 per watt, racking about $.25 per watt, installation about $.50 per watt.

You may save more because of taxes on your electric bill, we get charged a school tax and I think a library tax based on my gross electric bill, those taxes are reduced to almost zero

Some states may have net metering witch is a great incentive, you buy electricity from the utility at retail and they buy it back from you at retail.

Although some states you buy your electricity at retail and the utility buys it back from you at wholesale prices, that makes things more complicated.

Electric rates always go up!!

 

 

 

 

 

 

 

volvoclearinghouse
volvoclearinghouse UberDork
2/19/19 7:23 a.m.

In reply to TVR Scott :

This is almost exactly the system we got.  15 panels, 14k before rebates/ incentives, about 9k actual out of pocket.  

Panels face due south.

Just waiting on the final inspection and then we'll get PTO (Permission to Turn On)

They finished installation on Saturday.  Please excuse the side of the house- repointing the walls is next, followed by vinyl siding.  

AngryCorvair
AngryCorvair MegaDork
2/19/19 7:52 a.m.

In reply to youngfg :

and someone is sure to ask "why do you hate schools and libraries?"

TVR Scott
TVR Scott Reader
2/19/19 9:37 a.m.

In reply to volvoclearinghouse :

Looks great!  Enjoy the new system!

woodanator
woodanator None
2/19/19 10:22 a.m.

This thread is very helpful for me. Thank you very much for your replies.

bobzilla
bobzilla MegaDork
2/19/19 10:27 a.m.

I like the idea of ground mounting. I have a couple of spots I could put a decent sized array. 

californiamilleghia
californiamilleghia Reader
2/19/19 12:42 p.m.

As far as the panels , is there a big jump in output in the near future with newer models coming soon ?

Will there be solar roofing material so you just redo your roof  to keep the rain out and solar at the same time ...

Robbie
Robbie UltimaDork
2/19/19 1:27 p.m.

vch - VERY COOL!

cali - Tesla already makes solar roofing tiles https://www.tesla.com/solarroof

1988RedT2
1988RedT2 UltimaDork
2/19/19 3:35 p.m.

It may be worth mentioning that PV panels can present special challenges to firefighters.  If your insurance company finds out that you have an installation on your roof, your premiums may go up, or you may be dropped.  Probably most relevant to DIY installs.  Be aware, and adhere to code requirements.

https://www.wired.com/2017/05/rooftop-solar-panels-great-planet-terrible-firefighters/

https://www.sfpe.org/page/FPE_ET_Issue_92/Fire-Concerns-with-Roof-Mounted-Solar-Panels.htm

 

Boost_Crazy
Boost_Crazy HalfDork
2/19/19 6:59 p.m.

In reply to youngfg :

I find It really interesting to see the costs associated with solar in other parts of the country. Your electricity rate is so cheap, that your payback should have taken forever. But the cost of your system is a fraction of what the same system would cost out here in CA- The demand is great because energy prices are high, so installers can charge more. Your equipment costs were also low, which modules did you find for $.50 per watt back then? Are they 72 cell?

volvoclearinghouse
volvoclearinghouse UberDork
2/19/19 9:36 p.m.
1988RedT2 said:

It may be worth mentioning that PV panels can present special challenges to firefighters.  If your insurance company finds out that you have an installation on your roof, your premiums may go up, or you may be dropped.  Probably most relevant to DIY installs.  Be aware, and adhere to code requirements.

https://www.wired.com/2017/05/rooftop-solar-panels-great-planet-terrible-firefighters/

https://www.sfpe.org/page/FPE_ET_Issue_92/Fire-Concerns-with-Roof-Mounted-Solar-Panels.htm

 

Notice how the panels don't go all the way to the peak or sides?  Our county has codes for setbacks just for that reason- firefighters.

Of course, the building is all masonry construction, with a steel roof, so it's relatively fire-resistant.  

volvoclearinghouse
volvoclearinghouse UberDork
3/11/19 8:56 a.m.

We are officially a 'NUG' - 'Non-Utility Generator'.

Solar panel array switched on at 9:50AM, Monday, March 11, 2019.

cool

WonkoTheSane
WonkoTheSane Dork
3/11/19 9:24 a.m.
californiamilleghia said:

As far as the panels , is there a big jump in output in the near future with newer models coming soon ?

Will there be solar roofing material so you just redo your roof  to keep the rain out and solar at the same time ...

As the guy I ended up buying from told me, "There's always a "major breakthrough!" coming juuuuuussssttt a few years away."  In reality, this is a very well understood technology and there will be continuous incremental improvements as materials get a little better/cheaper/etc, but probably not any major breakthroughs coming to the home owner in the next decade.  And if there was, you probably wouldn't want to be the guinea pig for it :)   

The good news is that once you size a system, that's it.  It has a known degradation over its life, but it's not like your 11 kW system will someday not be able to run the latest power company app, so it's useless like a phone or computer, it'll just keep truckin' along.  Perhaps in the future, they can install a system half the size and still make 11 kW, but that won't make your system obsolete in anyway.

 

volvoclearinghouse - Yay!  It's pretty cool, isn't it? :)

TVR Scott
TVR Scott HalfDork
3/12/19 10:12 a.m.

Here's a fun solar-related pic - this is my solar output graph from the 90% solar eclipse a few years ago:

 

z31maniac
z31maniac MegaDork
3/21/19 4:38 p.m.

Since the Fed Tax credit (and some state and local I believe) is still in play and we a ton of southern exposure on our roof, I've got someone coming out on Monday morning just to give me an idea.

immortality
immortality New Spammer
3/27/19 6:22 a.m.

I have solar panels and they are great when they are working but the maintenance cost outweighs the saving. But incredibly - some new homes come as standard with roofs that cannot support a decent sized solar system. Ensure you get written assurances from your builder that every roof face can be filled with solar panels. We had a great experience with [ozzie solar canoes] If you have to 'upgrade' to do this it should only be a few hundred dollars.

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