Solar photovoltaic on the house as an investment

[aja8888]

OK, enough of the LED stuff. Let's (including me) get back on the PV topic.

 

[skipro33]

LED discussion to be continued here;
http://www.early-retirement.org/for...r-ready-for-prime-time-77691.html#post1605076

 

[alistair]

Even LED bulbs are not rated for 25 years. Half that at best.

Most are quoted at 25,000 hours which is approximately 23 years at 3 hours a day (I run mine about 5 hours a day average over a year). Type of bulb and heating will impact use. For instance, ceiling can lights usually will get hotter than a table lamp. So for even the same LED bulb, I'd expect the table lamp use to be significantly longer than a kitchen ceiling can light using the exact same type of bulb.

Still, it's typically the LED itself that gets the 25K hr rating, not necessarily the accompanying electronics, which can be quite heat sensitive.

Dyson's new $600 table lamp claims it's LEDs will last 37 years. Their design uses a heat pipe to keep the electronics cool.

I'm sure a reliability engineer could explain it better, but my understanding is that claims of this sort mean that 50% of product X will last Y years. They warranty the first few years to take care of infant mortality of a product, but after that, most devices should last close to the expected lifetime, assuming "normal" use conditions.

All this said, the LED technology is still advancing at a rapid clip and reducing in price. PV tech is dropping dramatically in price but the efficiencies are slower to improve. (Comparing relative improvements of conversion efficiency for PV vs lumens/watt improvements of LEDs.) Associated PV electronics such as inverters, are however probably improving in capability and lower price just as fast as LEDs.

 

[daylatedollarshort]

I'm an Amazon Prime junkie and have bought all but a few of our LEDs and dimmers from them. But the 40W (equiv) are costly, even there. So until the prices come down, I have CFL's in those fixtures.

I am not sure exactly what they were called, but I took advantage of some daily deal type specials on LEDs in the past.

 

[NW-Bound]

Eh, the OP has requested that we stay with PV discussions.

A question for the group...

Is there a cheap device that you could use to determine how much sunlight you get a different locations in your yard

As I said, we have a lot of trees.... I am looking at my garage roof and it is getting some good sun right now... but I also see a part that is shaded because of a tree... so a foot or two can make a big difference...

I have seen a handheld light meter. I guess one should cost less than $100. The problem is you want more than a snapshot at one instant in time. What about the change in the sun position throughout the day and seasonal variations?

By the way, locations at the same latitude do not get the same insolation; cloud cover varies greatly from one place to another. For example, New Orleans and Houston are at a lower latitude than AZ or NM, but do not have the same potential solar power because of cloud cover or high cloudiness. On the other hand, when the ambient temperature is hot, the panel loses its efficiency, so that's a negative score for AZ hot desert.

One thing about tree shades: avoid it. I have a small 10W solar panel I use to maintain battery of a car that I park for long periods. By playing with it and moving it about, I saw that a bit of shade can cut the power to 1/10 or less.

 

[NW-Bound]

An explanation about how a bit of shade can kill the power of a panel.

Panels are made by wiring cells in series. Each cell is a 4" square producing 0.5V each. A residential panel has either 60 or 72 cells in series. If a cell does not produce current because of shade, not only that it does not contribute its 0.5V, but it substracts several, yes several volts from the string. This is the reverse breakdown voltage of the junction; the solar cell is basically a diode with a Zener breakdown voltage. This breakdown voltage is a function of the manufacturing process, and also varies from cell to cell.

So, no partial shade!

 

[nokkieny]

This year is one of those years where I am searching for tax deductions, so I got the idea of a solar installation for my business. I have 12k square feet of metal roof that gets baked all day long. I live in georgia and for a variety of factors, I know it is not the best investment here. But, it is something I would enjoy.
After reading this thread, researching and watching a few youtube installations for the micro-inverter systems. I find an article about a new law that changes the maximum commercial output from 100kW to 125% of peak usage, and allows power companies to charge solar customers a fee just because they are connected to the grid What? The supposed upside of the bill is allowing customers to lease systems, which from what I have seen is just a bad idea, at least here where power is cheap. Georgia legislators are idiots! I was getting excited about this and now it basically makes no sense at all. 125% of my peak usage is probably 5kW.
I don't understand why power companies don't want to buy back solar, couldn't they just do it at slightly less then their cost to burn coal and call it a day?

 

[ERD50]

.... I find an article about a new law that changes the maximum commercial output from 100kW to 125% of peak usage, and allows power companies to charge solar customers a fee just because they are connected to the grid What? The supposed upside of the bill is allowing customers to lease systems, which from what I have seen is just a bad idea, at least here where power is cheap. ... I was getting excited about this and now it basically makes no sense at all. 125% of my peak usage is probably 5kW.

I don't understand why power companies don't want to buy back solar, couldn't they just do it at slightly less then their cost to burn coal and call it a day?

Well, if you are connected to the grid, you are using that infrastructure. You still want power for your building if the sun goes down right? Gotta pay for that.

The payback on solar PV would be far longer than the life of the system if you were getting paid less than they pay for coal generated kWh. You get paid the retail rate now - where else can you take a product back to the supplier, and have them pay you retail instead of wholesale prices? It's already a screaming deal (not counting the externalities of burning coal, which should be counted).

Try taking the extra gallon of gas you have left over from the lawn mower at the end of the season - you think they will give you $5 for it? No way.

Georgia legislators are idiots!

What, you were expecting Georgia legislators to be different from the rest of them?

-ERD50

 

[samclem]

I don't understand why power companies don't want to buy back solar, couldn't they just do it at slightly less then their cost to burn coal and call it a day?

The sketchy availability of solar just makes it less valuable to the power company than coal. If they could "pull" it from you when >they< need it, rather than having you "push" it in when available, it would have a higher value. But, in that case, they'd just buy their own solar panels and make their own solar power on an industrial scale a lot cheaper than we can do it.

Actually, the cutback of the forced solar buyback might end up being good news for you. If less solar power is forced into the grid at peak solar times, the power companies might find it economical to build their own solar production facilities. Unused >large< rooftops might be appealing to them. 12K sq ft ain't gigantic, but it's big. Maybe you can lease it to them.

(oops, cross-posted with ERD50)

 

[Texas Proud]

This year is one of those years where I am searching for tax deductions, so I got the idea of a solar installation for my business. I have 12k square feet of metal roof that gets baked all day long. I live in georgia and for a variety of factors, I know it is not the best investment here. But, it is something I would enjoy.
After reading this thread, researching and watching a few youtube installations for the micro-inverter systems. I find an article about a new law that changes the maximum commercial output from 100kW to 125% of peak usage, and allows power companies to charge solar customers a fee just because they are connected to the grid What? The supposed upside of the bill is allowing customers to lease systems, which from what I have seen is just a bad idea, at least here where power is cheap. Georgia legislators are idiots! I was getting excited about this and now it basically makes no sense at all. 125% of my peak usage is probably 5kW.
I don't understand why power companies don't want to buy back solar, couldn't they just do it at slightly less then their cost to burn coal and call it a day?

It has been a long time since I had to deal with business electricity... but when my BIL had warehouses there were two things that came into the cost of his electricity.... his actual use and his peak use... IOW, if they have to provide some huge amount of power at any particular time it would cost you for the whole month... I know there were some months when the peak was real high and the bill was much higher than normal....


I also remember back when I worked at a small bank... they would run some of their backup generators to prevent a peak from happening...


So, you have to determine what that will cost you compared to just using grid... it still should save you money....

 

[NW-Bound]

To be fair, if power companies are required to buy solar power from you, then when you need power from them, they should be allowed to charge you what it costs to maintain all that equipment sitting idle, waiting to fire up the moment you need it.

Again, Germany is now paying utility companies big bucks to maintain idle equipment. Yet, on good days, they have so much solar and wind power that it has no place to go.

People do not realize that solar and wind power cannot be stored and stockpiled like coal, oil, or uranium rods.

 

[jimnjana]

People do not realize that solar and wind power cannot be stored and stockpiled like coal, oil, or uranium rods.

not yet. Tesla wants you to believe that its new battery is the answer. But I think an affordable solution is likely in the next decade.

The other side of the coin is that rooftop solar reduces the need for utilities to build new power plants, thus all customers money. Our power bill has fuel costs separated from base rate charges that all customers pay. I think that is likely the fairest way to pay for overhead.

 

[skipro33]

One way to 'store' energy is with something called 'pumped storage'. The utility I worked for built a 400mw (MegaWatt) hydro power plant that used off peak generation sources to pump water back uphill to a reservoir so that it could make power during peak demand times. We use wind generation at night, when there are less customers and the wind blows anyways, to provide the electricity to pump the water back up from the lower reservoir to the upper one, then make hydro-electric generation when we need the peak generation.

 

[skipro33]

Well, if you are connected to the grid, you are using that infrastructure. You still want power for your building if the sun goes down right? Gotta pay for that.

The payback on solar PV would be far longer than the life of the system if you were getting paid less than they pay for coal generated kWh. You get paid the retail rate now - where else can you take a product back to the supplier, and have them pay you retail instead of wholesale prices? It's already a screaming deal (not counting the externalities of burning coal, which should be counted).

Try taking the extra gallon of gas you have left over from the lawn mower at the end of the season - you think they will give you $5 for it? No way.



What, you were expecting Georgia legislators to be different from the rest of them?



-ERD50

Billing for an energy producer to tie in to the grid is much different than a retail electric customer. Paying for generation, transmission and distribution on the producer level is different than for the retail customer.

A roof top solar generator is not getting paid by the utility company at retail rates. It's only banked at retail rates. Over generation, more that the owner of the solar uses in a year, is bought from the utility at spot wholesale prices. Right now, that's around 2 or 3 cents a kWh. Far from the 16 cents for tier one. Even then, a very close look at the net metering regulations stipulate that the utility company is under no obligation to pay you for over generation, that they only need to keep track of the net use between you and them. It's in the fine print. I have a neighbor who over generates and has sued the utility for the failure to pay for his over generation. He's lost and now in a class action to see if they can do better. I don't give 'em much hope. Careful reading convinces me they do not have to give you a dime for over generation.

One thing to note; in California the state is selling carbon credits. It's a cap and trade deal where the amount of hydrocarbons, CO2, is fixed for the state on a yearly basis. High polluters can buy the credits low polluters have left at the end of the year. It's an auction. My credits are 'owned' by the electric company I use to tie into the grid. I don't get any benefit, they do.

 

[ERD50]

Billing for an energy producer to tie in to the grid is much different than a retail electric customer. Paying for generation, transmission and distribution on the producer level is different than for the retail customer.

A roof top solar generator is not getting paid by the utility company at retail rates. It's only banked at retail rates. Over generation, ...

All of this varies by state and utility company, so we can't generalize. I was assuming the residential case where you do not over-generate (that's a lot of panels for one home!), so the 'banking' in effect means you get paid retail rates for your production.

Maybe nokkieny needs to look into becoming an actual commercial producer - that must have different rules? It wouldn't make sense to limit a 'producer' to 120% of their usage - they're producers, not customers! Like a solar farm.


-ERD50

 

[jimnjana]

This year is one of those years where I am searching for tax deductions, so I got the idea of a solar installation for my business. I have 12k square feet of metal roof that gets baked all day long. I live in georgia and for a variety of factors, I know it is not the best investment here. But, it is something I would enjoy.
After reading this thread, researching and watching a few youtube installations for the micro-inverter systems. I find an article about a new law that changes the maximum commercial output from 100kW to 125% of peak usage, and allows power companies to charge solar customers a fee just because they are connected to the grid What? The supposed upside of the bill is allowing customers to lease systems, which from what I have seen is just a bad idea, at least here where power is cheap. Georgia legislators are idiots! I was getting excited about this and now it basically makes no sense at all. 125% of my peak usage is probably 5kW.
I don't understand why power companies don't want to buy back solar, couldn't they just do it at slightly less then their cost to burn coal and call it a day?

You need to find out how your power company handles solar. In my area of FL we have net metering which works well for me. In some municipalities the power company purchases excess.

 

[nokkieny]

You need to find out how your power company handles solar. In my area of FL we have net metering which works well for me. In some municipalities the power company purchases excess.

So from what I have read GA is a net metering state but there is no rules on how low buyback rates can be.

I started calling around today and my situation is not very fun. My power is billed and maintained by the city. It is a relatively small city, so just getting to someone who can give me information about permitting and net metering rates is going to be a struggle, currently I am waiting for a call back that I know I won't receive.

Assuming the buyback rates will be low if anything, I am starting to lean towards just covering my needs, getting my feet wet and going from there.

 

[fosterscik]

I've always been interested in solar but don't plan to stay in my current house long enough to make it a worthwhile investment (IMHO). BUT now my DD is thinking about it and has asked for advice...

She lives in a TX city with generous rebates for solar (30% discount + another 30% of the remainder in Federal credits). Her proposed system of 4653 kWh/year has quoted total installation cost after rebates of $4452.

That amount of power will save $550/year. If I ignore inflation in power costs (to offset opportunity loss on the money) the break-even point is $4452/$550 = 8 years.

I'd go for it. Any opinions before I make that recommendation?

It's a single inverter system with a 15 year parts + labor warranty on all parts. As an aside I'm thinking of suggesting a sunnyboy 3000TL-US inverter (rather than the quoted sunnyboy 3000-US) so than she will have 1 "protected" socket that will operate during power outages when the sun is shining. I'm guessing it will add $200 to the install but will get a quote. Will this be valuable? Anyone have experience with these fully isolated circuits?

 

[daylatedollarshort]

I'd go for it. Any opinions before I make that recommendation?

What I have wondered are what are the likely annual maintenance costs? What is the life span before they become out of date?

 

[fosterscik]

What I have wondered are what are the likely annual maintenance costs? What is the life span before they become out of date?

The system has an "all-in" 15-year local-installer warranty that covers all failures and repairs. The panels are quoted to be "Hanwha Q-Cells, Q.PRO BFR - G3 260" which appear to be a good choice with 12-year warranties from the manufacturer. Hanwha specifies at least 97% of nominal power during the 1st year with a max. 0.6% degradation per year; >92% of nominal power after 10*years; >83% of nominal power after 25*years (if they last that long!).

Provided all components last 8 years her costs should be fully recaptured. If they last 15 years or longer she will do very well. Even if the inverter fails and the installer declares bankruptcy, a new replacement is "only" $1500..

 

[ERD50]

...

Provided all components last 8 years her costs should be fully recaptured. If they last 15 years or longer she will do very well. Even if the inverter fails and the installer declares bankruptcy, a new replacement is "only" $1500..

Also consider the comments earlier in this thread about roof repairs. Residential roofs often don't last 25 years (and does this roof has a few years on it already?), how much do panels add to the cost of a roof replacement?

-ERD50

 

[samclem]

As an aside I'm thinking of suggesting a sunnyboy 3000TL-US inverter (rather than the quoted sunnyboy 3000-US) so than she will have 1 "protected" socket that will operate during power outages when the sun is shining. I'm guessing it will add $200 to the install but will get a quote. Will this be valuable? Anyone have experience with these fully isolated circuits?

I have no experience with the product. The ability to plug in for power when the sun is shining during a widespread outage could be very handy. It might be enough to recharge cell phones, recharge cordless tools which might be handy after a hurricane, etc, keep the food in the fridge/freezer from going bad, run some fans or even a very small window AC unit during the heat of the day, run a sump pump to move water, etc. If the cost is really just $200, I'd think it would be well worth it in most places--if it comes in handy just once, it could easily pay for itself.

 

[fosterscik]

Thanks for the reminder about roof replacement etc. I'll have to get DD to explore those costs. Her roof is ~10 years old so 10 -15 years left. My quick googling suggests remove and reinstall costs are in the $1000 range for a small array like she wants.

 

[fosterscik]

For those interested the protected socket idea here's some blurb from the manufacturer:

Sunny Boy 3000TL-US
SMA has recently unveiled its newest line of grid-tie inverters with a variety of new and improved features to help system owners get the most out of their systems. These new UL certified inverters continue to raise the benchmark in solar inverter technology. The Sunny Boy 3000TL-US comes standard with an impressive list of features.

Transformerless for higher efficiency and lighter weight
Dual maximum power point tracking for more design options
Reduce effects of partial system shading with OptiTrac™
Secure Power Supply (SPS) provides daytime power if grid goes down
Sunny Boy 3000TL-US comes with a Secure Power Supply that is able to send up to 1,500 watts of power to a dedicated outlet in the case of daytime grid failure.

So maybe 13.5 Amps @ 110V on the circuit max. Maybe enough for a small window AC, but would be touch and go. But that amount of power would be very useful for all the other suggestions by Samclem.

 

[jimnjana]

So from what I have read GA is a net metering state but there is no rules on how low buyback rates can be.

I started calling around today and my situation is not very fun. My power is billed and maintained by the city. It is a relatively small city, so just getting to someone who can give me information about permitting and net metering rates is going to be a struggle, currently I am waiting for a call back that I know I won't receive.

Assuming the buyback rates will be low if anything, I am starting to lean towards just covering my needs, getting my feet wet and going from there.

when we produce more than we use it goes to a reserve that we draw from as we use more than we produce in the summer....no buyback