DirkH asked in a comment if I’m keeping any records on the performance of the 12-kW PV system my family installed on our home last year. He thinks the German Weather Service statistics concerning the amount of sunshine in Germany for June seem a little high. First, the sun statistics from the German Weather Service DWD seem to be spot on, and agree with the production of our PV system.
The first half of June was really good – plenty of sunshine. Our system produced over 1000 kwh in the first 18 days alone, with many days producing over 60 kwh. But things got bad starting June 19. The last 10 days have been really terrible. Yesterday was the worst summer day for solar energy I’ve seen so far (only 16 kwh). This month we’ve produced 1325 kwh up to now, which is okay.
Our PV system has a data-logger, but I haven’t taken the time to get it all set up on my PC notebook etc. and so I can’t present you with all these neat graphics. I just write down the result every evening and calculate output each month.
Monthly outputs so far:
Jul 2012: 957 kwh (July 10 – 31)
Aug: 1442
Sep: 1005
Oct: 682
Nov: 300
Dec: 173
Jan 2013: 114
Feb: 339
Mar: 833
Apr: 1211
May 1131
Jun (so far) 1310
I’ve spoken to other system operators who have had them a few years, and they tell me this year overall is the worst. It’s been cloudier than usual. Overall our PV system hasn’t performed as well as I hoped. The panels only work at about 75% when it’s too warm, they rarely operate at their rated capacity, even when the sun shines directly on them.
They tell us that the system pays for itself within 9 years or so. But if the power converter breaks down and you have to replace it, then you can add another 2 years. Then there are some maintenance costs, insurance, etc. So if we’re making money after 12 years, I’ll be surprised. Then there’s also the disposal costs. I seriously doubt I’ll be able to just throw everything out along with the household rubbish.
I bought the system only because 1) the person who sold it to us is a customer of ours, and 2) I didn’t want to be forced to pay high feed-in rates to subsidize other PV operators. Unfortunately it’s a screw, or be-screwed situation. Believing that we’re doing something good for the planet is totally idiotic. The feed-in act benefits (if at all) property owners with good southern exposure. The rest get the shaft.
After almost one year of operation my assessment is: I’m a little disappointed, and expected more from it. On a scale of 1 to 7, 1 = extremely satisfied / 7 = extremely disappointed, I’d have to award a score of 4.
By the way, on the other side of town where I live there’s a field covered with solar panels. Yesterday I rode my bike past it and the weeds growing underneath the panels are now starting to come through the gaps between the panels. So it’s possible that in about a week I’ll have another one of those infamous weed-covered PV system photos, like the one I wrote about here. I’ll be going back in a few days with a camera to see if I can get some shots before the owner mows the weeds down.
Photo: by P Gosselin
I rest my case, it’s only an electric toothbrush:
Notrickszone goes green
“They rarely operate at their rated capacity, even when the sun shines directly on them”
Exactly my experience of a small 15w panel I used for some years to keep a battery charged at a remote outbuilding. And your dramatic reductions of output on cloudy days also mirrors what I observed. Soooo… all those claims that “Our systems continue to generate power on cloudy days” may be true, but the actual amount of power is negligible.
My installation was intended to run an ultrasonic pest scarer, and a small fluorescent strip light. The reality, as I found out, was that in summer the charge regulator earned its keep, but in winter the panel was useless, and I had to take a freshly charged battery out every couple of weeks. Now extend that to a nations electricity supply…
Pierre,
Thanks for the update.
As I read of the potential extra costs I wonder if your panels are self cleaning? I live in a dry area ~ 8 inches (200+ mm) of precipitation annually. I think this would be a problem and would favor ground versus roof-top systems. Also, a ground installation could tilt and pan (like a sunflower) but that, too, would add initial and ongoing costs.
A power company in Washington State put in a solar array when they built a wind farm on a high and windy site. An engineering study showed that panels that could follow the sun could not last in the winds, so things are set securely in concrete and steel.
Looking forward to the photo –
We did have enough moisture to give the brush and weeds a good environment this spring. They are relentless!
I haven’t cleaned them since they got installed. a thin film of grit has formed. Most dust, pollen, bird droppings get washed off by the rain. I’m told I should wash the panels only with soft distilled water and not with, tap water. I hear a lot of different things and sometimes I’m not sure what is the best thing to do. I could have a cleaning service come in and do it, though the costs probably won’t be covered by the gains from the slightly higher efficiency.
The panels should be covered with glass. The only thing that speaks against using tap water is when you live in an area with hard water that forms a whiteish limescale residue after drying.
(I had to look up the word limescale and found this article with a fascinating electron microscope photo of limescale crystals:
https://en.wikipedia.org/wiki/Limescale )
Rainwater can be used to keep the glass clean and, on hotter days, to periodically spray a mist onto the panels to keep them cool. The reverse flow through most PV cells increases substantially when the junction temperature gets above about 50⁰C.
If you’re not shy about playing with electronics, you can build a simple controller that uses e.g. a windshield washer pump to spray water into the panels when they need it. Power the pump and controller off a separate small panel (20W or less may do, depending on how far you have to lift the rainwater); from which you can also ascertain a proxy for the intensity of insolation, but measure the temperatures of the production panels.
The water spray trick is used widely in solar “competitions” and can increase output by 20% or more.
Installers are usually shy about leaving a good convective space underneath roof-mounted PV collectors as it increases the wind load enormously. In winter, it can also produce a snow-trap, which has the potential to over-load the roof.
Oh yeah. Wash with rainwater and a good glass cleaner like windscreen washer detergent. That should leave little residue.
First, Pierre, thanks. I heard from others that they expect break-even after 12 years. Quite risky in my regard, too long term.
John F. Hultquist
29. Juni 2013 at 16:42 | Permalink | Reply
“Also, a ground installation could tilt and pan (like a sunflower) but that, too, would add initial and ongoing costs.”
The sale and development of these so-called solar tracker systems ground to a halt around 2008; at which point the cost of PV panels had dropped to the point that the marginal utility of a tracker became smaller than its cost. You simply compensate for the lack of tracking by buying more panels. Trackers have moving parts, exposed to the weather, so they are relatively expensive and need maintenance.
Yes, it’s good Pierre that you put up that solar PV system so you will have first-hand experience and tracking system how useful (or useless overall) it is. We’re the beneficiaries too, as we read such personal account.
Don’t confuse “tracking the system performance” with a mechanical tracking system…
https://en.wikipedia.org/wiki/Solar_tracker
…as I said, nowhere in Germany are mechanical trackers still installed; even large commercial acre-wide solar fields don’t use them.
BTW, I got an interesting ad. All Siemens shareholders: run for the hills, dump them while you can. Here comes Siemens’ Underwater Windmill.
http://www.siemens.com/entry/cc/en/stories.htm?stc=wwccc135123#underwaterwind-hd
Known as the “Herring Shredder” been about for quite a while.
The RITE Project
http://verdantpower.com/what-initiative/
This IMVHO has some merit, the energy it is drawing on is at least predictable. However my experience of large rotating equipment in such an inhospitable environment shouts “downtime”! Unpredicatable downtime!
Those are dolphin shredders!
http://verdantpower.com/what-initiative2/
Those output figures are what I would expect. 12kW producing a peak of about 1300 kWh in 28 days. They’re “working” for just over 100 hours a month in summer. 4 hours a day equivalent of peak.
You might see the average peak-equivalent approach 6 hours, depending on weather and orientation. You’ve already noted the monthly average dip below the 1 hour per day equivalent during the winter months.
PV operates mainly on subsidies.
I am always interested in facts. I hope you will publish a full one-year kWh production number when you have it. I would also be interested in knowing the cost of electricity in Germany; the cost of your panels; and the amount of the incentives (including feed-in tariffs) you’ve been given.
Here in Seattle, the local “greens” point to Germany as an example of the success of solar energy. I am intensely skeptical, and would be interested in comprehensive data. I am singularly UNINTERESTED in pure opinion, selective data, or ideology. All I care about is what works.
As an aside, I own a small electric car here, and have carefully monitored its performance. Unlike the owner of this website, I’m a believer in EVs for limited-duty applications, pending a capacity breakthrough on the batteries.
Cost of electricity in Germany:
Private households pay about 26 Eurocents a kWh, or about 33.8 US cents.
Consumers above 60 MWh a year can get commercial tariffs for about 10 Eurocents when they are excempt from paying the renewables cross subsidies or 16 Eurocents when they’re not excempt. Excemption is granted for companies that compete on international markets; the current government handles it leniently.
There is competition; you can choose to buy electricity from several hundred companies, but 2/3 of the end price are fixed taxes and cross subsidy fees so the offers vary only very little.
Thanks very much for the facts. Wow, your rates are high. In the U.S., electric rates vary quite a bit, especially in those places where “time of day” pricing sets high rates in mid-day and low rates at night. In Seattle, we pay 4.6 cents/kWh for the first 300 kWh a month, and 10.71 cents/kWh for the rest.
What about solar incentives there? Can you detail them?
In most places in the U.S. with solar incentives, they are in the form of a straight swap. People whose panels feed surplus electricity into the grid get a credit for each kWh, sometimes in the form of the meter simply turning backward.
In Seattle, there are very generous additional subsidies based on where the equipment is made. If your panels and inverter are made in the State of Washington, you get an additional incentive of about 55 cents/kWh paid directly by the utility (they write you a check), plus a credit for every kWh your panels generate, even if you use that power.
Additionally, the U.S. government gives a 30% tax credit on the cost of the equipment, including installation. Even with all these incentives, the payback in Seattle (the cloudiest city in the continental United States) is roughly 10 years, and the panels are rarely able to generate a very significant percentage of a typical household’s electricity use.
I am very curious to know what incentives Germany provides, and how much you’re paying per kWh of capacity for the equipment, including installation. I ask because I’d like to know, in thorough detail, what the actual economics are at the individual level.
Thanks very much for your first response, and I hope you’ll respond again.
Jake, current tariff for new roof installations is 17.8 Eurocents I think. Guaranteed for 20 years. The grid operator must not reject any solar elec. produced. The tariffs guaranteed for new installations were much much higher in the past, above 30 cents, they fell over the years. At the same time the capacity installed grew exponentially and continues to do so. Currently the guaranteed FIT drops by 1 or 1.5% a month; the government varies the cumulative drop depending on the newly installed capacity. Once 53 GWpeak are reached no new subsidy guarantees will be given; we’re above 30 GWPeak now.
Generally the subsidy was in the past 5 years always at a point where one could say, you break even after about 12 years if you don’t have big repairs. As prices for panels dropped, so did the subsidy.
Cost of solar panels is 0.70 EUR per Wattpeak AFAIK – but I didn’t track prizes very closely. Recently the EU commission declared anti dumping import tariffs on Chinese PV, starting with 11%. They will grow in half a year to 47%. China retaliated with tariffs on French wine (not on German cars, as Germany argued against the tariffs. The Chinese are retaliating in a very measured fashion, I must say.)
Basically all the international FIT schemes are modified copies of the German solar FIT law. 50 nations and 50 provinces have copied it. Germany introduced it in 1999 when a red-green govt came to power.