SOLAR PANELS ON THE ROOF

[jimbo123]

My sister in law went to a large chain store for light bulbs and got into a sales pitch for solar panels to be installed on her roof. Is there any plus for the home owner to have these installed as far a savings on her electric bill ? . The best I got out of her was it did not cost her anything on the install, but they would split the savings by using the panels. I advised her to think about this long and hard because there is a lot to think about as , What happens when the roof leaks ? Who covers the cost for removing and reinstalling the panels ?

Does anyone see a plus for having these panels installed ?

 

[petersonra]

no currently available PV technology is cost effective unless someone else is footing part of the bill.

like anything else, the quality of the install varies by contractor. if the roof leaks, you call them up and they either accept responsibility for the leak and fix it or decline to do so. Just like any other contractor.

 

[kwired]

The best I got out of her was it did not cost her anything on the install,

Who is paying for them if it doesn't cost her anything? She likely misunderstood something, or they were really misleading, or both.

Once this is installed you will save on energy purchased from the utility, but you need to figure how much will be saved and how long it will take to pay back the installation plus maintenance costs - which a leaking roof because of the panel existence is going to be part of those maintenance costs. This equipment is not that cheap that it is normally a quick payback, but if you get other money back somehow like tax incentives - it becomes more worth looking into. Every install has it's own unique circumstances so you can't say one answer fits all either and need to evaluate every potential install based on it's potential.

 

[ron]

I had solar PV installed on my roof. Considering tax incentives, etc, the payback is ~10 years.

Sometimes, companies will provide financing for the project like a PPA and sell you the power for a "hair under" what you are paying.

I laid out a portion of cash up front and keep whatever the panels make. The finance company paid for the equipment and install and got all tax incentives. I also have a kWh generation guarantee so the vendor is responsible to maintain the system for 20 years so I get the guaranteed production, or they pay me for the kWh's they don't make for me.

The keys are the tax incentives and the 10 year payback.

 

[DarylH]

In addition to what's already been posted, it's important to know what the homeowner's electrical usage is currently and what utility costs are.

In my case in southern CA we have a multi tier rate system where tier 1 and 2 are in the pennies range and then tiers 3 and 4 jump up to the 20 plus cent range. So for best payback the solar system needs to be sized to generate enough energy to keep you out of zone 3 and 4, but not necessarily so big that you never hit zone 2.

In my case we installed a 3.1 kw system that generates between 14 to 17 kWh daily. The monthly savings for me were in the $100 to $150 range and payback would have been closer to 7 years after federal and state tax incentives and a utility rebate.

A recent California university study found that the resale value of a PV system on homes being sold was $5 k per kW for newer systems.

In my case when I sold my home earlier this year, the new home buyer did not understand the value of the system so I did not convey the system with the house and took it with me when I left.

Now I just need to get around to doing the permit and installing the system on my new house . . .

 

[gadfly56]

Anthony Watts at "Watts Up With That" did a brief article on the installation of solar panels on his home in Chico, CA. Apparently the electrical provider is moving to demand based billing for residential, and peak rates are going for $0.90/kW-hr. He financed out of pocket for $25,000 with COSTCO and expects a payback period of about 9 years. Follow up article here. He goes into a lot of detail on his install with more than enough info for someone to get started on their own project.

 

[DarylH]

Thought it might be interesting to take a look at my current bill and work out the numbers for the production I was seeing out of my system on the old house and what my savings will be for the new house.

Total usage was 1,281 kWh (up considerably from my old house
(new house has a pool and a few other energy consumers the old house didn't)

Baseline allotment is 358 kWH for 32 days at tier 1: $0.02119/kWh = $7.59
Tier 2 is 100-130% of baseline and 107 kWh at: $0.04501/kWh = $4.82
Tier 3 is 131-200% of baseline and 251 kWh at: $0.22437/kWh = $56.32
Tier 4 is more than 200% of baseline and 565 kWh at: $0.24437/kWh = $138.06
Total for the tiers is $206.79

On top of this there are several additional charges:
bond charge of $0.00513/kWh
summer electricity generation of $0.12916/kWh
state surcharge tax of $0.000290/kWh
state regulatory fee of $0.000240/kWh
These total $0.13482/kWh, and 1281 kWh * $0.13482/kWh = $172.70442

Total bill is $377.61 after $1.88442 of other adjustments.

There were 32 days in this billing cycle. If my system generated an average of 15 kWh per day which is pretty typical for clear sunny summer time days in SoCal, that would be a total of 480 kWh.

This would reduce my tier 4 charges to 85 kWh or $20.77145, a savings of $117.28855
It would also reduce the total usage from 1281 kWh to 801 kWh and the additional charges to $107.99082, a savings of $64.7136.

The total bill reduction then would be $182.00215.

This is pretty much the best case for this system as it's for the June-July billing and the longest days of the year. Production drops off as the days get shorter, but it's somewhat offset by the fact that my roof angle was a bit better suited to the sun angle for shorter days so I wasn't getting peak possible production on the summer days.

With this system I'm leaving some saving opportunity on the table. There are still 336 kWh left in tier 3 and 4 that cost 22.4 and 24.4 cents per kWh - that's $122.39 when you factor in the additional charges per kWh. So really I could go from a 3.1 kW system to a 4.5 kW or even 6 kW before the additonal cost of the panels aren't really being paid back at the 2 and 4 cent per kWh rate of tier 1 and 2.

I've also just put in a variable speed pool pump that should whack about $100/month off my bill so between that and the PV system I should be pretty close to being back in the tier 1/2 range again.

And there's also the added benefit of feeling green

 

[gadfly56]

Thought it might be interesting to take a look at my current bill and work out the numbers for the production I was seeing out of my system on the old house and what my savings will be for the new house.

Total usage was 1,281 kWh (up considerably from my old house
(new house has a pool and a few other energy consumers the old house didn't)

Baseline allotment is 358 kWH for 32 days at tier 1: $0.02119/kWh = $7.59
Tier 2 is 100-130% of baseline and 107 kWh at: $0.04501/kWh = $4.82
Tier 3 is 131-200% of baseline and 251 kWh at: $0.22437/kWh = $56.32
Tier 4 is more than 200% of baseline and 565 kWh at: $0.24437/kWh = $138.06
Total for the tiers is $206.79

On top of this there are several additional charges:
bond charge of $0.00513/kWh
summer electricity generation of $0.12916/kWh
state surcharge tax of $0.000290/kWh
state regulatory fee of $0.000240/kWh
These total $0.13482/kWh, and 1281 kWh * $0.13482/kWh = $172.70442

Total bill is $377.61 after $1.88442 of other adjustments.

There were 32 days in this billing cycle. If my system generated an average of 15 kWh per day which is pretty typical for clear sunny summer time days in SoCal, that would be a total of 480 kWh.

This would reduce my tier 4 charges to 85 kWh or $20.77145, a savings of $117.28855
It would also reduce the total usage from 1281 kWh to 801 kWh and the additional charges to $107.99082, a savings of $64.7136.

The total bill reduction then would be $182.00215.

This is pretty much the best case for this system as it's for the June-July billing and the longest days of the year. Production drops off as the days get shorter, but it's somewhat offset by the fact that my roof angle was a bit better suited to the sun angle for shorter days so I wasn't getting peak possible production on the summer days.

With this system I'm leaving some saving opportunity on the table. There are still 336 kWh left in tier 3 and 4 that cost 22.4 and 24.4 cents per kWh - that's $122.39 when you factor in the additional charges per kWh. So really I could go from a 3.1 kW system to a 4.5 kW or even 6 kW before the additonal cost of the panels aren't really being paid back at the 2 and 4 cent per kWh rate of tier 1 and 2.

I've also just put in a variable speed pool pump that should whack about $100/month off my bill so between that and the PV system I should be pretty close to being back in the tier 1/2 range again.

And there's also the added benefit of feeling green

As long as the green you're feeling isn't coming out of MY pocket, have fun.:thumbsup:

 

[DarylH]

As long as the green you're feeling isn't coming out of MY pocket, have fun.:thumbsup:

Well maybe it is a little. The price of the system initially was ~$22 k, but after the federal tax credit (your part ) and the other incentives, the out of pocket cost was $14.5 k.

BTW, when I later priced the various parts, mainly the PV panels and inverter, I found the markup was about 100%, which was about what I expected. So a DIY guy could save a fair bit . . .

 

[gadfly56]

Well maybe it is a little. The price of the system initially was ~$22 k, but after the federal tax credit (your part ) and the other incentives, the out of pocket cost was $14.5 k.

BTW, when I later priced the various parts, mainly the PV panels and inverter, I found the markup was about 100%, which was about what I expected. So a DIY guy could save a fair bit . . .

Watts' cost for a 9KW system was $25,000 all in, and he purchased the parts through COSTCO. No government incentives.

 

[Pharon]

Unless the payback is 5 years or less, I don't know why anyone would ever consider this.

 

[gadfly56]

Unless the payback is 5 years or less, I don't know why anyone would ever consider this.

Considering that 10-year treasuries are going for 2.41%, a ten year payback (10% ROI) is more than ample economic justification. Even a 20 year payback would make sense, except now you're probably pushing the envelope for component lifetimes. The only thing that irks me is subsidizing these installs with tax money, whether state or local. Tax credits or deductions are fine; I just don't cotton to the idea of Uncle Sam cutting someone a check for it.

 

[GoldDigger]

Watts' cost for a 9KW system was $25,000 all in, and he purchased the parts through COSTCO. No government incentives.

A cost under $3 per DC watt before incentives is darned good for most areas of the country for a professional install. A DIY install that is that low after considering the value of the owner's time is also respectable.
Some jurisdictions make it hard for DIY and some incentive programs require a registered installer's sign off.

 

[gadfly56]

A cost under $3 per DC watt before incentives is darned good for most areas of the country for a professional install. A DIY install that is that low after considering the value of the owner's time is also respectable.
Some jurisdictions make it hard for DIY and some incentive programs require a registered installer's sign off.

Watts had a professional installer do the job.

 

[DarylH]

Watts had a professional installer do the job.

As did I first time around.

To be clear, by DIY in this context I was thinking more in terms of the audience of licensed electricians in this forum.

 

[jaggedben]

no currently available PV technology is cost effective unless someone else is footing part of the bill.

That's just not true. We're installing PV for a projected cost of 11cents/kwh or less. In California no one pays less than about 14cents/kwh, and many people pay 30 or 40 cents for high usage. (In Hawaii rates are even higher.)

Considering that 10-year treasuries are going for 2.41%, a ten year payback (10% ROI) is more than ample economic justification. Even a 20 year payback would make sense, except now you're probably pushing the envelope for component lifetimes....

Thank you.

My hope, and guess, is that PV panels will still be functional after 20-25 years at which time systems can be overhauled for a fraction of the original system cost.

 

[gadfly56]

As did I first time around.

To be clear, by DIY in this context I was thinking more in terms of the audience of licensed electricians in this forum.

Ahh yes, a slightly different kettle of fish, true.

 

[gadfly56]

That's just not true. We're installing PV for a projected cost of 11cents/kwh or less. In California no one pays less than about 14cents/kwh, and many people pay 30 or 40 cents for high usage. (In Hawaii rates are even higher.)



Thank you.

My hope, and guess, is that PV panels will still be functional after 20-25 years at which time systems can be overhauled for a fraction of the original system cost.

Hope springs eternal.:roll: Per Grape Solar, the panels have a guarantee of 90% of initial output at 10 years and 80% of initial ouput at 25 years. It's a fairly large dice roll as to the true condition of any panel at that far out. You can do accelerated aging tests, but a system like a solar panel isn't like a board with a coat of paint. Electrons pushing through all those tiny interconnects will cause electromigration which may reduce capacity well before gross physical failure. And certainly, it's doubtful the inverters will go much past the 20-25 year mark. Likely you'll be replacing the roof as well, so even the support structures will be removed and, even if still in good condition, will have to be reinstalled at the least.

So to sum it up, it's likely to be a total replacement by the 25-year mark. By then, of course, who knows what will be available.

 

[jaggedben]

Hope springs eternal.:roll: Per Grape Solar, the panels have a guarantee of 90% of initial output at 10 years and 80% of initial ouput at 25 years. It's a fairly large dice roll as to the true condition of any panel at that far out. ...

It's really not that big a dice roll because this is 70 year old technology and there are plenty of silicon panels that have been operating for 25 years (or more) in the open environment. So the 80% or 90% guarantee that manufacturers offer is based on actual data.

And, btw, the degradation curve flattens out as time goes on, so if a panel loses 20% power in the first 25 years it will lose a fraction of that in the next 25 years.

 

[Iron_Ben]

That's just not true. We're installing PV for a projected cost of 11cents/kwh or less. In California no one pays less than about 14cents/kwh, and many people pay 30 or 40 cents for high usage. (In Hawaii rates are even higher.)



Thank you.

My hope, and guess, is that PV panels will still be functional after 20-25 years at which time systems can be overhauled for a fraction of the original system cost.

Respectfully disagree with you, in our fair state anyway. I handled about a hundred solar installs before retiring from the power company earlier this year. In Louisiana, the customer got/gets an 80% rebate between federal and state. So a $25,000 system gets a $20,000 combined rebate/tax credit and the customer is out of pocket for only $5,000. With that, the typical payback is 7 or 8 years. Without that 80%, well.......

We were a fairly high cost provider (residential rates between 11 and 13 cents/kwh depending on cost of fuel mix and a few other variables.) Some of our competitors were down around 9 cents per, so a solar install would have an even longer payback for those customers.

Ben