Solar photovoltaic on the house as an investment

[Another Reader]

In the Phoenix market, a solar lease kills a lot of sales and can make a property in the lower price ranges very difficult to sell. FHA buyers generally cannot take on the additional lease payment and often do not meet the lessor's lease assumption criteria. People that are not solar enthusiasts are concerned about maintenance and roof leaks. As near as I can tell, solar adds no value to the property and may limit the pool of buyers. Here in Silicon Valley, solar is largely considered an amenity. Does it add value? Hard to conclude that from the paired sales I have looked at.

 

[Texas Proud]

Why are you even concerned with this then? If it doesn't work for you, don't do it. And certainly don't go back in time to wonder if you should've done it then. Makes no sense.

I am not.... just debating the points presented....

Solar makes zero sense to me even if I wanted to do it... too much shade and bad roof angles...

Just pointed out a negative I had not seen mentioned....

 

[samclem]

But how do I make use of the energy that I produce, as I cannot pump it into the grid? I now have to put in at least two panels, so that they produce more than 500W to allow me to run a small window AC as a load dump. This is getting more complicated.

Two panels could run a small freezer. Make ice during the load dump period, blow air over it at night to cool the bedroom until morning (fan hooked to thermostat in bedroom). This has the advantage of being more complicated than your small AC unit idea.

Then, I remember reading about solar panels losing efficiency when hot, in fact the colder it is the better the efficiency if the lighting stays the same. For each degree C rise, the panel may lose 0.5%.

I climbed up to measure the temperature with an infrared thermometer. The ambient air was 105F, but the panel was 149F, or 65C! The panel ratings are always at 25C (77F). Where I am, if it gets that cool I do not need power that bad.

Do these panels typically have any type of heat sinks on the back? It would seem that a small investment in AL fins would pay off, esp if the panels are on angled racks. Even a small 10w fan might be worth the power use (and maybe improve longevity of the panel). Or, run some water pipe on the back side which would really pull some heat away could be used to pre-heat water for the house or heat a pool.
And, I never see mirrors or high reflectance panels in front of angled-rack systems, I recall with thermal solar panels (hot air or hot water) that these improved performance by a considerable amount. Maybe the (longer) wavelengths of the reflected light aren't useful to the PV panels.
I'm sure the PV hobbyists have considered and rejected all these ideas. But the panels could be a limitless source of [-]wasted time and money[/-] fun for a tinkerer.

 

[target2019]

I am not.... just debating the points presented....

Solar makes zero sense to me even if I wanted to do it... too much shade and bad roof angles...

Just pointed out a negative I had not seen mentioned....

I am reading this topic, here and there. May have missed relevant comments, but I found, when researching this topic about five years ago, that the number of trees we have, and the age of our roof, are significant factors. How your home sits also is something to consider. A rough guess at the time told me that the additional costs to prepare would easily exceed $25,000.

I decided at that time that getting a new roof, cutting down a dozen trees or more, and paying for solar was not the way to go. I added insulation to our attic, and that has helped control costs over the last few years.

Last year I drove through a farming community about 30 miles from here. Each day I went past an impressive array set on the ground. In fact, two homes sat in a very large open field, each with an array. Since there were no trees for perhaps a half mile to interfere, the array seemed to be perfectly positioned, facing the south. Many of us can not come close to that ideal.

 

[samclem]

Since there were no trees for perhaps a half mile to interfere, the array seemed to be perfectly positioned, facing the south. Many of us can not come close to that ideal.

No, but many yards have a sunny area where a 200 sq ft outbuilding could go (a tool shed, garage for the mower, workshop, etc). These can be built inexpensively and oriented however is needed to catch the sun, all the circuitry/etc can be placed inside the shed for convenient access. A single-plane "shed" roof has a lot of area (200 sq ft building footprint = 240 sq ft roof (with overhangs) = 3700 watts max production or approx 550 kwh/month--that's all we use most months), and covered with metal roofing will last through two or three generations of panels. And--who doesn't need a shed!
I think this would also overcome a lot of the resistance that future buyers might have. It's not "part of the house", and the house looks entirely "normal" with no extra racks or holes in the roof. If they don't like the shed out back (that pays their entire electric bill!), they can knock it down.

 

[NW-Bound]

Nope, nobody ever puts heatsink on solar panels. The extra weight and cost cannot be justified. At this point, if I still want to play with this, I would just forget about the off-grid idea and dump the power into the grid to offset my consumption. It is not sanctioned, but how can they find out, with the minuscule power of one panel?

If I had room, I would have a ground mounted array like DaveMartin's to face south perfectly. I would also be able to tilt the panels a few times a year to optimize to the seasonal sun angle. Imagine all that power I would be sending to the grid. Ka Ching! It's like owning a small power plant. I would feel like king of the hill.

My boondock home where the sun is even more intense (clear air due to high altitude, cloudless sky), and cool temperature (for higher panel efficiency), and where I have land is a perfect spot for solar power. But I use so little electricity up there (no AC needed), and I do not think they have net metering up there. And then, I am not there often, and any thief with a wrench can unbolt and haul away the whole thing in a couple of hours.

 

[skipro33]

That would save me $675 per year. 15 years to break even, if I ignore the interest & earnings on the $10K, or if I could get a 0% interest loan.

Assuming no maintenance costs. Assuming nothing like a tree grew up and shaded the panels.
15 years is a long time to wait before seeing any net benefit.

Remember rates will raise over 15 years. As much as interest or earnings in a more conventional investment, I can't say. It's a way to diversify for those who do pay high rates, live in sunny areas of the nation, plan to stay in their home until the initial capital is recovered.

The savings are after tax, unlike most investments which are tax deferred.

 

[target2019]

No, but many yards have a sunny area where a 200 sq ft outbuilding could go (a tool shed, garage for the mower, workshop, etc). These can be built inexpensively and oriented however is needed to catch the sun, all the circuitry/etc can be placed inside the shed for convenient access. A single-plane "shed" roof has a lot of area (200 sq ft building footprint = 240 sq ft roof (with overhangs) = 3700 watts max production or approx 550 kwh/month--that's all we use most months), and covered with metal roofing will last through two or three generations of panels. And--who doesn't need a shed!
I think this would also overcome a lot of the resistance that future buyers might have. It's not "part of the house", and the house looks entirely "normal" with no extra racks or holes in the roof. If they don't like the shed out back (that pays their entire electric bill!), they can knock it down.

That size shed would not fly in my location. Sheds need permits, and someone would surely point out that the 10x20' shed is out of spec with ordinance. Maybe I can talk neighbor into erecting a large array over their pool...

Our property, for reference, is attached.

 

[samclem]

That size shed would not fly in my location. Sheds need permits, and someone would surely point out that the 10x20' shed is out of spec with ordinance. Maybe I can talk neighbor into erecting a large array over their pool...

Our property, for reference, is attached.

In some locations, small outbuildings without a permanent foundation (e.g. on "skids") don't need a permit. But, there are usually size limitations. In our case, even a 10' x 10' structure would let us meet about 50-60% of our requirements--and if they adopt tiered-rate billing, it might be the most expensive 50%.
But you've got a lot of trees, which is a great "problem" to have. It points out the whole silliness of this house-by-house solar concept. Let me do a fractional buy-in to get my 200 sq ft of panels, along with a hundred other people, on top of some tree-free warehouse or parking lot overhead covers. Economies of scale, easy maintenance, etc. They get the $$ to buy the panels, I get the kwh offset to my residential utility bill. I'll cede the whole thing to the developer after 25 years.

 

[daylatedollarshort]

Our MO is looking for low cost, low tech conservation solutions until solar costs come down a bit further. We usually drop our bill by $5 - $10 a month each month compared to the same month the year before. It is kind of like the Kaizen method meets the Mother Earth News method of energy bill reduction.

This past month we started using a thermal cooker meant specifically for pasta, added ventilation to the garage to keep it from heating up the house on hot days, replaced a few more bulbs with LEDs, and I bought a used, second steamer basket for the top of my rice cooker (to cook rice/grains, meat and veg all at the same time and without using the non-energy efficient stove). None of those are huge drops by themselves but over time 5 - 10 items like that each month all add up.

 

[aja8888]

................replaced a few more bulbs with LEDs,..............

I applaud you for the energy conservation effort on your part, but it seems every time I read a post of yours in that direction, you are replacing more and more lights with LEDs (which is good).

The question I have is are you replacing ALL of your bulbs with LEDs or just in the high use areas? We just finished this exercise and I just replaced the ones we use a lot. I could not see any justification for replacing bulbs in the attic or in closets as the payback is not there.

 

[ERD50]

Nope, nobody ever puts heatsink on solar panels. The extra weight and cost cannot be justified. ...

I think that is true, but I have seen plans to utilize the heat. I would think there must be many industrial processes that could utilize this low level heat (I've seen articles about a laundromat with solar water panels, so maybe that would work - combine PV with water heating?).

Hmmm, does it make any sense to use a heat pump to elevate the temperature of the water for other uses? Probably cheaper to raise the temp by burning stuff?

But a true industrial sized installation at least makes this stuff something to consider, it just can't be justified on a home scale installation.

... It points out the whole silliness of this house-by-house solar concept. Let me do a fractional buy-in to get my 200 sq ft of panels, along with a hundred other people, on top of some tree-free warehouse or parking lot overhead covers. Economies of scale, easy maintenance, etc. They get the $$ to buy the panels, I get the kwh offset to my residential utility bill. I'll cede the whole thing to the developer after 25 years.

Yep, and as I point out above, a large installation might be able to take advantage of other efficiencies.

This whole concept of subsidizing home scale installations is just so silly - I shake my head every time I think of it. And it's the environmentalists who should be opposing it the most. If we are going to subsidize solar, do it based on power production (maybe a weighting for the dirtiness of the marginal daytime power on the local grid - which is probably NG peaking plants) and do it with efficient installations - more 'green for the buck.

-ERD50

 

[daylatedollarshort]

I applaud you for the energy conservation effort on your part, but it seems every time I read a post of yours in that direction, you are replacing more and more lights with LEDs (which is good).

The question I have is are you replacing ALL of your bulbs with LEDs or just in the high use areas? We just finished this exercise and I just replaced the ones we use a lot. I could not see any justification for replacing bulbs in the attic or in closets as the payback is not there.

We did the high use areas that used basic 60 watt type bulbs first. Some of the fixtures are more complicated because they require specialty type bulbs / are enclosed / outside so those are getting replaced as we have time, are updating the fixtures anyway or find cost effective replacement bulbs. Our recent addition of more LEDs happened because painters accidentally broke a couple of our older original issue light fixtures so we replaced them with newer fixtures that could use LED bulbs and then we also found an incandescent bulb when we were decluttering one of the kids bedrooms that only get used on school breaks these days.

 

[samclem]

Our MO is looking for low cost, low tech conservation solutions until solar costs come down a bit further.

I do wonder how much lower the after-subsidy solar panel prices will go. We're basically enjoying low prices due to Chinese overproduction (i.e. they are at/close to the price of production, it has not been good for these companies) and the (last gasps?) of a federal subsidy program for buyers.
Betting against lower prices for tech products is usually not smart, but maybe most of the cutable costs have been cut?

 

[meierlde]

Hmmm, does it make any sense to use a heat pump to elevate the temperature of the water for other uses? Probably cheaper to raise the temp by burning stuff?



-ERD50

NOte that you can buy heat pump based water heaters: Heat Pump Water Heaters | Department of Energy and pool heaters:Rheem Classic Heat Pump Pool Heaters Series
But what I have not seen that would make sense for folks in the southern states would be a device that could take the heat thrown out by the AC and heat the pool with it. At least in the spring and fall it could extend the pool season.
If you live by a lake you can use the lake as a heat dump in the summer and a source of heat in the winter. (Sort of geothermal heat without having to drill wells).

 

[target2019]

In some locations, small outbuildings without a permanent foundation (e.g. on "skids") don't need a permit. But, there are usually size limitations. In our case, even a 10' x 10' structure would let us meet about 50-60% of our requirements--and if they adopt tiered-rate billing, it might be the most expensive 50%.
But you've got a lot of trees, which is a great "problem" to have. It points out the whole silliness of this house-by-house solar concept. Let me do a fractional buy-in to get my 200 sq ft of panels, along with a hundred other people, on top of some tree-free warehouse or parking lot overhead covers. Economies of scale, easy maintenance, etc. They get the $$ to buy the panels, I get the kwh offset to my residential utility bill. I'll cede the whole thing to the developer after 25 years.

It is something I think about, and keep abreast of developments. We will not be in this home in 5 years, so I think about the next family. As you can see, some buy houses and take out most trees in backyard, and in goes the concrete pond, aka swimming pool. With our luck someone will buy our home and stipulate we must remove that awful shed!

If at all, I would do a smaller array on the 2-car attached garage. But it will not be a maximum solution. In the house photo I posted, the southern sky is perpendicular to the length of our house. As you can tell, I have thought of this as I relax in the back yard, watching the squirrels. . .

 

[daylatedollarshort]

I do wonder how much lower the after-subsidy solar panel prices will go. We're basically enjoying low prices due to Chinese overproduction (i.e. they are at/close to the price of production, it has not been good for these companies) and the (last gasps?) of a federal subsidy program for buyers.
Betting against lower prices for tech products is usually not smart, but maybe most of the cutable costs have been cut?

I think eventually we will have affordable community solar. There are places around us that bake in the sun, have few trees and the panels could be put in any direction. It makes a lot more sense from a community standpoint to have the panels located some place more optimal for gathering sun rays other than where our house roof is located. But for now our community solar option costs more per kwh than just regular grid electric, and the regular grid electricity here is already relatively expensive.

We may downsize before too long, our roof is not the right direction, most of our energy costs are from gas heat, not electricity - so for us solar on the roof is not a good option at current prices. Even if prices do not drop we will just stay on the grid and continue to reduce consumption instead.

 

[Texas Proud]

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...

 

[samclem]

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 don't know the answer, but the best spots will change over the course of the year ( what is clear today might be in the shade in winter when the sun is at a lower angle). I wonder if there is a site that can use a picture of your property (from Google Earth), let you tag the heights of relevant things (roof peak and eaves, tree canopies, etc), and then spit out a report of solar exposure for the whole year, maybe a reading for a point every 3' or so. It could incorporate local historic cloud cover, too.

 

[ERD50]

I don't know the answer, but the best spots will change over the course of the year ( what is clear today might be in the shade in winter when the sun is at a lower angle). I wonder if there is a site that can use a picture of your property (from Google Earth), let you tag the heights of relevant things (roof peak and eaves, tree canopies, etc), and then spit out a report of solar exposure for the whole year, maybe a reading for a point every 3' or so. It could incorporate local historic cloud cover, too.

It would be some work, but the 3-d drawing program 'SketchUp' does some of this (or at least the free google version did, I think ownership has changed). You can create an architectural model, add trees, etc, and tell it the co-ordinates, and you can view the shade throughout the day and seasons. Very cool.

I know that some (most, all?) panels include the blocking diodes, but I'd use the simple assumption that if there is any shade on the panel, the output is near zero for that time. It just doesn't make much sense to install them where there is shade during any appreciable amount of the day, especially in summer when most of your power is developed (longer days).

-ERD50

 

[alistair]

I definitely think people should not overlook energy efficiency before going the PV route. Lighting isn't your biggest electrical use, unless you're trying to have your house spotted from the space station at night. A/C, dryer, refrigerators, dishwasher and plasma TV individually use a lot more power than most of your lights together will (yes there are some people who this won't be true).
Consider wringing out max efficiencies out of appliances against the cost of PV. If you have ideal PV circumstances (e.g. big, open, unshaded south facing roof, tax credits, etc.) then PV may still make sense. For a lot of other people, extra attic insulation, caulk around leaky windows, etc. will make more dollars and sense than PV.

 

[target2019]

I definitely think people should not overlook energy efficiency before going the PV route. Lighting isn't your biggest electrical use, unless you're trying to have your house spotted from the space station at night. A/C, dryer, refrigerators, dishwasher and plasma TV individually use a lot more power than most of your lights together will (yes there are some people who this won't be true).
Consider wringing out max efficiencies out of appliances against the cost of PV. If you have ideal PV circumstances (e.g. big, open, unshaded south facing roof, tax credits, etc.) then PV may still make sense. For a lot of other people, extra attic insulation, caulk around leaky windows, etc. will make more dollars and sense than PV.

Very good point. When we moved in about 20 years ago, the dryer was an electric hookup. After a few years we redid the kitchen, and as part of that electrical upgrade we converted the 220 for the dryer to two circuits, and installed gas line for dryer.

 

[Mulligan]

I definitely think people should not overlook energy efficiency before going the PV route. Lighting isn't your biggest electrical use, unless you're trying to have your house spotted from the space station at night. A/C, dryer, refrigerators, dishwasher and plasma TV individually use a lot more power than most of your lights together will (yes there are some people who this won't be true).
Consider wringing out max efficiencies out of appliances against the cost of PV. If you have ideal PV circumstances (e.g. big, open, unshaded south facing roof, tax credits, etc.) then PV may still make sense. For a lot of other people, extra attic insulation, caulk around leaky windows, etc. will make more dollars and sense than PV.

My neighbor last year had more insulation blown into his attic (10 year old house) for $600 or so and has really crowed about his heating/cooling savings. Although he is 87 I believe, he crawled up there and marked the beams before they came so they wouldn't "rip him off".
I really need to add more to mine as it barely covers the cross beams. But since I had my metal roof installed it has cut my bill so much by that alone it has sapped the motivation to do it. Maybe next year...


Sent from my iPad using Tapatalk

 

[NW-Bound]

... But what I have not seen that would make sense for folks in the southern states would be a device that could take the heat thrown out by the AC and heat the pool with it. At least in the spring and fall it could extend the pool season...

+1

For years, it bothers me that there's nobody doing this, or that there's no mention of it. Except in the midst of the summer, my pool stays cool most of the time due to evaporation. And exchanging heat from the AC with that 80F water should allow much higher efficiency than with hot air of 120F up on the roof.

I often wonder if I could experiment myself by brazing together a heat exchanger between a freon line of a small AC and the pool water. But perhaps I will learn that the chlorine in the pool water will corrode that copper heat exchanger in no time.

If you live by a lake you can use the lake as a heat dump in the summer and a source of heat in the winter. (Sort of geothermal heat without having to drill wells).

Only if you own the lake or pond. The warmer or colder water may disrupt aquatic life.

 

[meierlde]

+1

For years, it bothers me that there's nobody doing this, or that there's no mention of it. Except in the midst of the summer, my pool stays cool most of the time due to evaporation. And exchanging heat from the AC with that 80F water should allow much higher efficiency than with hot air of 120F up on the roof.

I often wonder if I could experiment myself by brazing together a heat exchanger between a freon line of a small AC and the pool water. But perhaps I will learn that the chlorine in the pool water will corrode that copper heat exchanger in no time.



Only if you own the lake or pond. The warmer or colder water may disrupt aquatic life.

There do exist water source heat pumps, typically used in geothermal hvac systems (the heat is extracted or rejected to the ground water). Also there are a number of small hvac to hot water systems. Ideally if money were no object, then one would build a double loop system with clean water flowing to one of 2 heat exchangers, 1 for the pool and the other for ground water. Essentially the system would set upper and lower pool temp limits and use the ground water loop outside the limits. (assuming one is in the right kind of soil area). At the pool filter you would have a water to water heat exchanger with pool water on one side and the fresh water on the other. This would minimize the length of refrigerant piping. I doubt the economics works today but then a while ago solar economics did not work either.
Note that water heating units can go to 55c or 80 c depending on requirements.

Lets assume a typical 20,000 gallon pool, which is 160,000 lbs of water. To raise it 1 degree F would take 160k btus, A 5 ton ac unit is 60k btus, so it would take about 3 hours of running flat out to raise the water 1 degree. In looking around the web I found the knock on the hvac based heating is that it is slow, although if one used a 100k btu furnace it woud just be twice as fast. Now you might want an other pipeing loop with a radiator to pump pool water thru if it gets to hot. (going from 70 to 90 would thus take 3,200,000 btus, or about 53 hours of continuous flat out running of the ac unit.