Went solar

[orezok]

Just to throw one more curve ball. When we calculated our ROI, you have to calculate in Loss of Opportunity costs. That is $1.00 today is not $1.00 at 8 years or whatever is calculated as the break even. It might be 10, 12 or even 15 years in real dollars for break even.

 

[sodamo]

You are the one that blew off my legitimate question about how long will it take to pay for itself with a flippant remark about how long will I be paying the power company.

Poorly phased- probably
Flippant- no way

 

[clemsonfor]

The industry warranties for degradation tend to be 90% of rated value at 10 years, and 80% of rated value at 25 years. My panels (Sharp ND-216U1F) have a 25 year limited warranty. Their rating is 216 Watts with an initial tolerance of +10/-5%.

The data sheet for the panel also has temperature coefficients for the panels. The panels have their ratings at 25 degrees C. The panel I have has a derating of -0.485% per degree C. The data sheet does not state if this temperature is ambient or the surface of the cells. I'll go out tomorrow and measure my ambient vs. cell surface temperature so we can put a number on that.

So at 77 degrees F (25 C), the panel in "full light" makes 216 Watts of power. At other temperatures:
90F makes 208 Watts
100F makes 203 Watts
110F makes 197 Watts
120F makes 191 Watts
448F makes no power (and I suspect the plastic on the back is melting )

The temperature derating is linear, and I suspect it's only good for real planet tempuratures not the extrapolated zero power out point :laughing:.

Note also that as the temperature goes down, the output goes up. So:
50F makes 226 Watts
32F makes 242 Watts
0F makes 260 Watts

And again, there is probably a limit on this end too. Temperature has other effects on copper interconnections used. Temperature cycling is probably also a prime means of wear out, even though it takes decades. For here in North Carolina, I'll see an output range between 242 and 200 watts for my 216 watt rated panels. The "110 degree and they stop performing" doesn't make a lot of sense, and I suspect there is other criteria applied to the system performance that makes that temperature a cut off point (as orezok mentions).

ShenandoahJoe's post points out the difficulty of make decade long or more guestimates on payback periods, a point I danced around on a previous post.

BTW, in the last 24 hours I made 86% of the energy my house needed, and made money to boot! Lower temps means lower HVAC use, this is great time of year!

Pete

If you made 86% of daily use how did you make money you had to still purchase 14% right? or did you make 86% of your monthly requirement today alone?

 

[clemsonfor]

Yeah, as temp goes up you get more recombination of electron hole pairs at the junction. Noise and leakage current, both temperature dependent, impact the device in a function dependent way. I'm also guess that the junction voltage goes up as the temp goes down, just like any semiconductor junction. That's probably another factor in the thermal derating for the PV panels. The data sheet had thermal derating for power, voltage, and current (I just sited power). They did not have a voltage vs. temp curve, either because most consumers might not know what that's about or because at the end of the day it's just a big honking PN junction.

Cool story , didn't know photonic emissions were a leakage detection mechanism. I had a buddy who back in the days of EEPROMS (like the 2704) spent months working on methods of detecting how many electrons _per year_ leaked out of the floating gate. They tweaked the fab process and got it down into the single digits! I know a few more "you wouldn't believe what someone can measure" stories.

Be it electronics or mechanical stuff, it's amazing how thousands of people have spent decades just quietly understanding and improving stuff. I think a lot of people focus on the big break throughs and don't focus on the effect of lots of little 1 to 2 percent improvements.

Pete

You and Robert both just geeked out on me again!!

 

[eepete]

Clemsonfor: We pay 10 cents per KWH for what we use, we make 16 cents per KWH on what we produce. So there is a KWH break even and a dollar$ break even point. So if I make 65% or more of my energy, I'm ahead dollars wise for the day. In the last 7 weeks, I've averaged making 52% of my energy.

All good geeks can outgeeek other geeks in the own geeky area.

Temperature data I just took (all in F). It was a breezy day, full sun at time of measurment:

Ambient air temp: 67 F
Surface temp of panels (the front side) ranged from 86 to 94 degrees, depending on the amount of wind blowing (it was a breezy day).
Back side of the panels was 104 degrees F.
Measured at the solar zenith, output power of the array was 7300 watts.
Inverter case was at 84 degrees, exhaust air out was 102 degrees.

So in a no wind situation, the panel temp might be around 35 degrees hotter than ambient air. So on a 95 degree day here my 216 watt panels might produce 185 watts. Of course there are errors here since I can only measure the front and back side. Also on those hot summer days the humidity is higher and there is more haze, so the panels put out less. I was still getting 6500 watts out on 95 degree days at the peak. Perhaps the most important number is that from noon to 6 PM, I provided more energy than I used even if all the air conditioners were running. A nice peak load win.

Here's a picture of the watts produced for yesterday and today so far. We have less clouds today than yesterday.

Pete

 

[Boeing]

Hi Guys,
I have the same issue that the fellow on the long road has. The Power com. wants BIG $$ to bring in power. My property is in the Virginia hills with limited sun and shadows. I would be very interested in SOLAR but as I am already 62 I don't want an 18 year "break even". VEPCO will not ALLOW you to go on the GRID with your power.....how's that for progressive? I am now investigating WIND...but I would need lots of batteries for low wind days. That's not cheap either. I see SAILBOATS have small wind generators.....?

 

[beppington]

Hi Guys,
I have the same issue that the fellow on the long road has. The Power com. wants BIG $$ to bring in power. My property is in the Virginia hills with limited sun and shadows. I would be very interested in SOLAR but as I am already 62 I don't want an 18 year "break even". VEPCO will not ALLOW you to go on the GRID with your power.....how's that for progressive? I am now investigating WIND...but I would need lots of batteries for low wind days. That's not cheap either. I see SAILBOATS have small wind generators.....?

Diesel or propane generator?

 

[RobertN]

My Uncle was off-grid when he lived near Mt Shasta. He started out samll as he built his house. 1st, everything was gas. He had a propane fridge, gas dryer, and a few gas lights. He had two large pressure tanks on the well. And, generators. When he ran the generator, you had water, and regular electricity. He would also charge a couple batteries for a small TV, and a couple battery powered lights.

Later, he did add some solar. But for the washer, the well, his welder, lathe ect, he still used a generator.

He was in the mountians, and had shade issues. So, even before he moved back to town because of health issues he used a combination of power and gas(propane and gasoline). He used mostly wood for heating.

there are a lot of regional considerations to solar/wind/water generated power.

Hi Guys,
I have the same issue that the fellow on the long road has. The Power com. wants BIG $$ to bring in power. My property is in the Virginia hills with limited sun and shadows. I would be very interested in SOLAR but as I am already 62 I don't want an 18 year "break even". VEPCO will not ALLOW you to go on the GRID with your power.....how's that for progressive? I am now investigating WIND...but I would need lots of batteries for low wind days. That's not cheap either. I see SAILBOATS have small wind generators.....?

 

[Cat_Driver]

When people figure ROI on solar they never ever calculate the loss of revenue on the money they invested.

Example: Lets say I buy a solar system for 30 K CASH, and it has a 15 year ROI. I could double or triple that 30K in 30 years by hundreds of opportunities.

1. I could buy 30K worth of goods and sell them double my money then take the 60K (30 K doubled), and do it again, and again and again.

2. I could reduce the equity in my house payments and save many, may thousands in interest.

3. I could play the stock market, risky but still I would make money.

4. 30K I could invest in real-estate, peopel are still making money on flipping properties, OR I could use the 30K on a rental property and make the rental income and then the entire price of the property by selling it after 15 years, while the renter make payments of it.

Solar id still way too expensive and the pay backs id too far out for it to be a viable "investment" compared to paying current utility rates and working the solar money.

Now if people think they are saving the planet and that's their goal, then sure solar is the way to go........BUT then you have a few people saving the planet and Billions of people destroying the planet, so it's a no win situation. Sorta of like spitting on a forest fire.

With Mexico, India, China, Russia, and may more Countries duping trillions of tons of carbon in the air, dumping hazardous materials in the oceans by the ship load, there is absolutely nothing the USA can do alone to save the planet, and the others NEVER WILL.

 

[RobertN]

I think it depends on your situation. For us, we pay higher electricity bills than other parts of the US. Locally, there has been good ROI when selling a home.

Given the rate our bills have been rising, I see a shorter term payoff. We added equity in our house.

I guess it's kinda like a diesel pickup. Most people do not get thier investment back from investing in the diesel when they only own the pickup for a few years and low mileage. Definitely not the average owner.

you get the investment back when you have the thing for 300k miles and use it a lot for towing or hauling.

When people figure ROI on solar they never ever calculate the loss of revenue on the money they invested.

 

[Loren49]

I haven't read the whole thread so sorry if I'm repeating something. I believe that one of the ways that money is saved when the decision is made to go solar is that you become much more aware of your power usage. This helps you to conserve and become more efficient. In the long run much less energy is used and wasted. More efficient use does not mean a lower quality of life. My family (now just wife and me) has been off the grid for 28 years.

Loren

 

[clemsonfor]

Clemsonfor: We pay 10 cents per KWH for what we use, we make 16 cents per KWH on what we produce. So there is a KWH break even and a dollar$ break even point. So if I make 65% or more of my energy, I'm ahead dollars wise for the day. In the last 7 weeks, I've averaged making 52% of my energy.

All good geeks can outgeeek other geeks in the own geeky area.

Temperature data I just took (all in F). It was a breezy day, full sun at time of measurment:

Ambient air temp: 67 F
Surface temp of panels (the front side) ranged from 86 to 94 degrees, depending on the amount of wind blowing (it was a breezy day).
Back side of the panels was 104 degrees F.
Measured at the solar zenith, output power of the array was 7300 watts.
Inverter case was at 84 degrees, exhaust air out was 102 degrees.

So in a no wind situation, the panel temp might be around 35 degrees hotter than ambient air. So on a 95 degree day here my 216 watt panels might produce 185 watts. Of course there are errors here since I can only measure the front and back side. Also on those hot summer days the humidity is higher and there is more haze, so the panels put out less. I was still getting 6500 watts out on 95 degree days at the peak. Perhaps the most important number is that from noon to 6 PM, I provided more energy than I used even if all the air conditioners were running. A nice peak load win.

Here's a picture of the watts produced for yesterday and today so far. We have less clouds today than yesterday.

Pete

We'll have to wait till a forestry or timber harvesting/crusing question till i can outgeek you, and heck this stuff is science but i dont think its hard science so you prolly will still follow my explanation of said topic anyway.

 

[clemsonfor]

I haven't read the whole thread so sorry if I'm repeating something. I believe that one of the ways that money is saved when the decision is made to go solar is that you become much more aware of your power usage. This helps you to conserve and become more efficient. In the long run much less energy is used and wasted. More efficient use does not mean a lower quality of life. My family (now just wife and me) has been off the grid for 28 years.

Loren

i cant really get more concious of power useage. We try and wash all chlothes in multi loads back to back to take advantage of a hot dryer ( i guess we could hang them up, but were not at that point yet) wash only full dishwasher ( i heard this is cheaper than hand washing by the time u use all that hotwater and water) and heat with wood as much as possible, and turn only one light if we can in a room and cut out lights in rooms were not in. We dont have pretty lights turned on all over the house like my wifes mom, you can count 12 lightbulbs on (the normal kind) in the combo living/dining room in the evening!!!!

 

[MossRoad]

i cant really get more concious of power useage. We try and wash all chlothes in multi loads back to back to take advantage of a hot dryer ( i guess we could hang them up, but were not at that point yet) wash only full dishwasher ( i heard this is cheaper than hand washing by the time u use all that hotwater and water) and heat with wood as much as possible, and turn only one light if we can in a room and cut out lights in rooms were not in. We dont have pretty lights turned on all over the house like my wifes mom, you can count 12 lightbulbs on (the normal kind) in the combo living/dining room in the evening!!!!

As much as I do not like the light that is given off by compact florescent bulbs, they sure do use a lot less energy. But they sure do cost a lot more to replace. Do you use CFLs?

 

[Storm56]

I have no problem with someone that wants to purchase a solar system using their own money. I do not believe in tax credits to help pay for it though. If it was such a great deal everyone would do it and not consider the tax credit in the purchase price/payback calculations.

When someone gets a tax credit that means less money in the treasury coffers. Someone has to make that up and no matter how you slice it everyone that did not get a credit is paying the bill.

 

[charlz]

The school district I work for out here in the desert looked into solar. After all, what could be better than 330+ cloudless days. We talked to the sales people from several different solar companies and were given glowing reports on how much power we would produce.

We then had our professional engineers evaluate. A different story for us. It turns out that PV panels are most efficient at 59 degrees F. As the temperature climbs the cells produce less and less electricity and at about 110 degrees they about stop performing. Heat within the PV cell itself increases the internal resistance to a point that voltage diminishes to a minimum. Not a consideration for many, but it just didn't fit our environment.

I ran into the same thing when I lived in Vegas. There were no State incentives at the time and the ROI was 25 years, same as the warranty on the PV panels. When I found about about the temp thing though that really was a deal breaker... I would generate the least power when I needed it the most, hot summer days.

I would like to put in a solar DHW system here but it doesn't appear to be too feasible considering the location of various components. Still want to study it more though.

 

[beppington]

I believe that one of the ways that money is saved when the decision is made to go solar is that you become much more aware of your power usage. This helps you to conserve and become more efficient. In the long run much less energy is used and wasted. More efficient use does not mean a lower quality of life.

If I had to set my A/C 5 - 10 degrees warmer (I live in FL) that would be lowering my QOL.

 

[eepete]

Storm, all energy sources get some form of government subsidies. But I also realize that the argument "well, everyone else is getting money from the government" is a pretty weak argument. An interesting question is this:

If none of the energy sources we used received government assistance, tax breaks or preferential regulatory laws, then would the price of electricity be high enough that solar would be finically feasible with no tax credits? Wish I new the answer...

Moss Road, As for the CFLs, I put a lot of ceiling can lights in my house only to find out that the CFLs have much lower life in them. They are best when used in the upright or sideways position in an open air environment. In a can light, the electronics is taking the brunt of the heat from the bulb and it runs very hot. Often the plastic in the base turns brown from the heat. The capacitors and semiconductors have much shorter lifetimes than if they are kept cooler. Parts that can withstand the heat are much more expensive to use. Googling CFL problems has more on all this.
Fortunately, I also put a number of sconce type lights in my house for hallways and bathrooms and those work very well with the CFLs. I also used dimmers on incandescent bulbs for the bedroom and my office. With incandescents the combination of a slow ramp up when turned on and running at partial brightness means long life and lower energy use.

CFLs tend to not work from an economic point of view if they are on for less than 5 minutes. Like a well pump, they may run forever but only turn on so many times. Incandescence have the same problem, but with a lower price they don't have to turn on as many times to be cost effective. There is a lot of manufacturer variation in quality and how much heat CFLs can take, and some of the problem here has been a rush to market with poor/cheap designs. Another problem is that since the bulbs rectify the AC and make DC for the electronic ballast, they do not draw current like a resistive incandescent bulb. They draw a peak current near the top of the AC wave form, and they draw current out of phase due to the capacitor in the bulb (in other words, bad power factor). So the 13W CFL that replaces the 60W incandescent really requires generation capacity of close to 30 watts from the power plant, adds a lot of harmonic distortion, and has bad power factor. The power bill is good for the owner since there is no charge for harmonic distortion or power factor problems but the reduction of power plant resources and pollution is half of what it might seem. Bottom line, they have a place in the house, cut generation requirements in half, are great for the light you might leave on for an hour or two, but can't replace every incandescent bulb.

Note that LED lights will have the same sorts of problems. If you look at efficiencies (lumens per watt kind of stuff), and the incandescent bulb is a '1', then florescent is a '4' and LED is a '5'. But the LED still has electronics in it, still has the harmonic distortion and power factor problem, and still has the problem of getting rid of heat in a standard fixture where the electronics and bulb are in the same screw in device. The life of the LED is proportional to how cool you keep it, so there will be problems with companies cheaping out on heat sinking the parts as well as problems with the lifetime of the electronics driving the LEDs.

soapbox:
It's sad that the world can't agree on a form factor and connector style/pinout for external electronics to drive fluorescent bulbs and LED lights (different boxes for each type). When you remove the heat from the electronics, the life of the systems makes the economics work. But that means new fixtures and a means to access the electronics. Perhaps even sadder is that if the world can't agree on this sort of thing, how do we solve the really big problems?
/soapbox

If done right, both bulb types are economically viable in terms of high initial cost of the bulb vs. savings from low energy use. The two problems are getting the designs right and getting consumers who will pay now and save later.

Hope this wasn't a TMI post...

Pete

 

[charlz]

I haven't read the whole thread so sorry if I'm repeating something. I believe that one of the ways that money is saved when the decision is made to go solar is that you become much more aware of your power usage. This helps you to conserve and become more efficient. In the long run much less energy is used and wasted. More efficient use does not mean a lower quality of life. My family (now just wife and me) has been off the grid for 28 years.

I would agree with that... having recently bought an RV that we take camping/dirtbike riding. We are always 'boondocking' which is camping without a grid hookup, just what was in the battery when we started and what we can produce with a generator. Kind of an eye opening experience as to what you take for granted at a house where you just 'flip the switch'. Goes for water usage to

 

[clemsonfor]

As much as I do not like the light that is given off by compact florescent bulbs, they sure do use a lot less energy. But they sure do cost a lot more to replace. Do you use CFLs?

Yep in all my most used lights, slowly replacing all others. The old ones i have from like 5 years ago take a few seconds to come on, but the ones that you buy now are instant on, still a little warm up time but light the second you flip the switch unlike the half second delay of the older ones. Lowes this week has 6 (iguess 60watt) bulbs in a 6pack for $6. Lowes is always way cheaper than walmart or other places.

In my house i might only have non CFL bulbs on for a total of less than an hour a day at at that it is at most only 2 at the time in a ceiling fixture. I have all new kitchen appliances, energy star fridge, ele. oven and dishwasher are not energy star. non energy star washer and dryer as well, but i wont replace them anytime soon and the price of the star ones does not pay. My water where i live is only $3/thousand gallons so water saving does not save me big $$$.