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Switching To Solar Power — Six Months Later
ThinSkin writes "Slashdot readers may remember an article regarding ExtremeTech's Loyd Case's experiences with solar power for the home after one month of usage. During that time six months ago, it sure seemed like a great deal, but the tables have turned significantly once winter approached. While it's no surprise solar power generation is expected to dwindle during the winter, Loyd compares solar power data of the last six months to determine if solar power is still worth the time and money."
Who the hell uses that much electric power?
I want to delete my account but Slashdot doesn't allow it.
There's an important step that this guy missed: cutting consumption. I have a roughly 3000 square foot house, and the most I've used since August '07 is 700kWh in a month... and that was a month when I had visitors for basically the whole month, so we used a lot more power. My average is around 500.
Now... we don't know how big this guy's house is, or how many people live there. But really... 1,635kWh? That seems pretty excessive for any reasonable house. Maybe if he's got a bunch of servers on all the time, and has electric heat, and lives in a cold climate, but it still seems high.
I would have been interesting to see some numbers or estimates for the installation and maintenance cost... and the cost of the insurance. It's like a car. Even if you succeed to find the money to buy a Ferrari, will you have the money to pay the insurance and the maintenance costs over the years ?
Not only are you saving a lot by generating your own power (actually I'd like to see your annual generated power curve along side your savings from the years previous and the savings assuming you didn't have the solar panels installed) but you could still add panels to your roof to generate more power. I wonder what the break even point is for your system, when would more panels make sense or not? I also wonder if adjustments to your system to track the sun angle even in one dimension by lifting the panels with a motion system would be? What about adding solar water heating to your house?
Why didn't this follow up article include a Return on Investment number? It would be nice if he would have included the cost of the install and compare it to the difference in his electric bills. I'm curious to see how long it will take the install to pay for itself.
I don't know about the position in the US, but in Europe there is a market in energy efficient appliances, and a small change in cost for things like freezers can buy one with half the power consumption. It would be interesting to know if he did the exercise you suggest, and if so did a cost benefit analysis. After all, in Northern CA it might be that he is using air con which could be avoided by improved ventilation, planting, modifications to windows etc., or electric heating for part of the winter which could have been replaced more efficiently with roof thermal absorbers rather than PV.
From scarped cliff or quarried stone she cries "A thousand types are gone, I care for nothing, no not one."
Who ever installed the panels mounted them directly flat on the roof. That is bad.
They need to be angled for the best sun during the time the power need is greatest. Ideally they would be adjustable semi-annually/quarterly/monthly for the best angle. And if fixed would be biased toward the point of worst number of sun days and power need.
Doing a suboptimal installation and not accounting for sun angle is not a good installation and should be perform at a fraction of potential output.
Given the 40 degree difference in the sun angle between Summer and Winter, would it make sense to change the tilt on the panels to optimize the angle for the two seasons?
Maybe a screw jack could lift the top of the panels as winter approaches, then lower them again as you move into summer?
It's not like snow or ice would be a problem and you could probably get the screw jack from an old satellite dish (or Boeing surplus!).
Just a thought...
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I went back to his original article (the instalation). He said the estimate is that his anual utility bill will drop from 4400 a year to 1100 a year.
So I made a few assumptions.
#1-his power use will not increase. Not really likely but a future increase shouldn't change the ROI on his current investment.
#2-Utilities will just keep pace with inflation (assumed 2%)...power costs will stay porportinally expensive in the future. This is probably not ture as power prices tend to increase slightly faster than inflation. So this assumption will tend to increase the ROI.
#3-I assume he is financing it through his mortgage at about 5%
Therefore when I calculate out to 25 years I find that he would spend about $141,000 in power over the 25 years without slar. With Solar he would spend $35,233.
The Payoff date comes at about 12.5 years.
Because this is a follow up article. The first article includes the Roi figures along with the fact that California Rebated half the cost of the system ($36,000.00 dollars), which explains his up front costs of $36,000.00. Not bad for the size system he had installed and yes I've read the first article and understood the reasoning for the selected installation method, which was to reduce peak Energy Usage during Peak Summer Cost. That's right, his goal was to cut the summer cost of energy during the most expensive part of the year from PG&E (his uutility company).
Note that PG&E has a variable Rate cycle that has the greatest impact during the summer cooling period. This is why he wanted to reduce his summer electric costs, which the system did quite successfully.
Mod me up/Mod me down: I wont frown as I've no crown
MAKE:blog has some descriptions of some DIY sun-trackers to move the panel with the sun during the day.
All the ones I have seen installed around here are either on sun tracking stands or building side mounted at a fairly steep angle
to keep the snow off of them.
Got Code?
It's enough to power a small village in Africa, but not far from the average US monthly average of 920 kWh
A lot of it would be gone.
You can count on the returns for solar.
You can pretty much count on electric rates rising in the future.
She was like chocolate when she drank... semi-sweet at first and then increasingly bitter.
How dare he use a ton of electricity!
Notice that we aren't complaining about the energy usage of Bill Gates's house. That's because Bill hasn't made quite the campaign on carbon control and global warming. While flying around to summits in his private plane.
You could argue that his energy bills should be lower, after all, he's gone much of the time.
Basically, Al Gore is rich enough to actually reduce his footprint; but didn't until people made an issue of it. Even then, I remember reading that after energy saving renovations his electricity bill went up compared to the year before.
He's asking us to make sacrifices; shouldn't he lead the way?
I don't read AC A human right
Don't tell anyone, but there's a tab on the first page that's labeled "print". I don't get to wait for ads and pictures to load, but it has the text.
The cost of that cleanup, of course, will be borne by taxpayers, not industry.
I thought that only happened in Soviet Russia.
Slow down, cowboy! It has been 4 hours since you last posted. You must wait another few hours.
People talk about single solutions but that is not the answer. It will be a blended solution. It will be a combination of solar, natural gas, wind, water, AND nuclear. In Israel, ever since I can remember (80s) each house/condo has solar panels to help heat water tanks...which are also sitting under the sun. Wind turbines are in various areas (Atlantic City NJ has about 5 or 6 MAJOR wind mills). Water turbines can work well. In California they created these water turbines that are hidden into the cliffsides. So when surf hits it water is sent up (and back down) to generate electricity.
But all of those will not be enough. We also need to supplant that with natural gas and nuclear energy. We also need to find ways to recycle spent nuclear fuel and convert it to useful energy...put it this way if that spent fuel is SO radioactive (meaning having lots of energy) then we could harnass it - we just don't know how (i think).
Until we get warp power - a blended solution will be needed - but it can work.
I mod down so you can mod up. Your welcome.
And that's in the winter. It's a lot more in the summer because of AC. Granted our building faces south and in the winter time gets a lot of solar time when the sun is out.
Granted we're a business and we run several servers in house 24x7 for development, testing, and backup and about 25 PC's.
We put up as much solar as we could given our amount of roof space last October. We've seen our electric bill go down to around $700 - $900 per month. It's basically cut our bill in half. Now we had the cash on hand to invest in the technology, plus there were some tax write offs that made it advantageous to do so before December of 2008.
But we viewed it as a wise investment that freed up over $1000 a month in cash flow. That's about a $1000 per month we can spend on additional development. It doesn't sound like much, but it was enough to offer 2 paid internships this spring semester at the local university.
Will the investment still take 5 - 7 years to pay for itself? In raw dollars, yes. But there are intangibles as far as I'm concerned. We've found two really good interns for this spring semester. Just over winter break they were able to take a piece of one project and get it to a working beta. It was the final piece of the puzzle to finishing that product that is now on the market and we've already got 20 installs lined up totaling about 1/3rd the cost of the solar panels.
Granted, we knew what our limits were. We did it not to be green and save money. The cash was either going to be given out as dividends (we are employee owned) and taxed or retained as earnings and taxed.
"The problem with socialism is eventually you run out of other people's money" - Thatcher.
...a separate web server for each page request.
They are so extreme that they provide enough computers to server one page of HTML, then they throw it away.
Every time I start to have faith in humanity, I ruin it by driving to work between 7 and 8 am.
That article has a lot of consumption and billing numbers for each of utility and homegrown power, but it's hard to get exact performance comparisons because the numbers don't exactly measure the same things. There is no exact start and end date, just month names, and approximate mentions of offsets into them, not lining up generation and billing dates in either the solar generation half-year or the time before drawing from only the utility. And practically no data on income from overgenerating, selling back to utility or grid.
But there is enough data to make rough comparisons. They say their January/utility bill was $446, but their December bills are the highest (all of which extra usage was billed in the highest rate, 300% of the base rate). So let's say their average bill used to be $450:mo, or $5600 annually. However, they said up front that their annual bill is about $4400. We'll take the average of $5400. Now their July-December/solar bill is $389.39. Even if we call that $400, and so their annual/solar bill is $800, they're saving $4600 a year. They paid about $55,000 before rebates, about $37,000 after all rebates. Their utility bill savings pays off their installation investment in $37,000 / $4600 = 8.04 years. Pessimistically, they should be paid off in 9 years.
These systems have a minimum lifetime of 30 years (if you don't invest in an upgrade during that time). Even if energy rates stay the same in those 30 years (probably not, probably higher), that $4600 for 21 more years is $96,600, or 2.6x the installation cost. Total return is $133,600 on $37,000 investment, so 3600% Return on Investment over 30 years. If you invested that money in a compound interest account (either savings or some investment with an average annual return reinvested), you'd have to get 15.43% annual compound interest to turn $37K into $136K in 30 years. Conversely, if you took out a 30 year mortgage on your home at today's average rate of 5.63%, you'd net 9.8% benefit. Which means that it's worth mortgaging (part of) your home to invest in these, with a fraction of your old utility bills paid as mortgage interest, and getting $78K more ("profit", really utilities savings) after 30 years, with no out of pocket.
That could be even better than they say. Their reasons for failing to maximize their roof generating area don't seem compelling: "it would get a little crowded up there". Other than access to the panels for cleaning, who cares how crowded it is? It looks like they could double their area. Which would give them closer to zero Winter bills, but overkill in Summer that exceeds what's left (if any) during Winter, which exceeds their "zero annual bill" maximum for reselling overgeneration to the utility at retail rates. So probably about 1.5x the area would give them Summer overgeneration that would equal their Winter utility draw, netting zero bills. It's got to cost less than 1.5x to install just more area, because labor and shared components (especially the inverter that sells power back to the utility) are a substantial cost that doesn't increase at all at that rate. Say it costs 1.2x, or $44,400, but they save the full $5400 annually. That's still about the same time in payback (about 2% longer), but 3.7x the return. And the "green feeling" is complete.
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make install -not war
Al Gore's carbon footprint should be measured against people with similar incomes, not against the average Joe.
No, it shouldn't. If Al Gore insists on promoting things like the Kyoto Accord that measure country's carbon footprints independently of income, then he should expect the same on an individual basis. Anything less is total hypocrisy.
Solar PV is a good replacement for utility electricity, as this article demonstrates.
Solar heating of water is supposed to be even more economical. The equipment is cheaper (basically a black pipe looped across area), and captures a lot more than 20% of the sun's power in the heated water. The only problem is that the extra power not consumed by using the hot water (washing or heating the building's air) is lost, dissipated through the system, or discharged when it exceeds even the water tank's heat storage capacity. But the tank can be made very large, and its heat can be converted to electricity (inefficiently, but better than losing it). You don't get to send unlimited surplus power back to a "bottomless reservoir" like the surplus PV electric to the utility, but some large tank should be sufficient to store all the extra heat. And perhaps store some extra PV power beyond what the electric utility will stop taking when the net annual utility consumption reaches zero. Elevating the water stores energy at close to 90% efficiency (the multiplied efficiencies of the elevating electric pump and the electric turbine in the downpipe).
It seems that there's a compelling case for installing both, and using a large tank as storage that increases the total efficiency substantially beyond the basic operating parameters. Which sounds like it's even better than the 3-4x+ 30 year ROI from just the PV demonstrated in the article.
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make install -not war
Our building's insurance didn't increase after the installation, as its included by the insurance agency as 'equipment', just the same as the heating and cooling system. It didn't change the property tax for us at all, since the facility is already worth a few million, and land values have been going down in the area.
Annual maintenance costs for us have just been an hour or two of squeegeeing every 6 months. Other than that, it just hums along next to silently every day. The furnaces at the building require more maintenance.
I remember reading about solar shingles a few years ago, how it was supposed to be the next wave of solar power for the home, the price was lower for installation, etc. I did read that they were a bit less efficient, but you were able to cover a much larger area of your roof for the price, thereby more than offsetting the disadvantages.
Fast forward to today, everywhere I look people are still installing solar panels and I haven't seen a single new article, blog or discussion about solar shingles. Was the technology flawed?
I'd love some feedback on this, because there's a possibility I might build a home in the foreseeable future, and I'm definitely intending on going solar for both electricity and water, maybe even a heat pump. Proper insulation is a given, energy efficiency appliances, passive solar design. I'd love to shoot the works on this project.
Lil' Thindime, lilting a lacrimose lament, krashes the kwaint konfines of Kokonino Kounty