11.09.2013
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Photovoltaics after grid parity

Plug-and-play PV: the controversy

For years, we were told that people would switch to photovoltaics without any need for subsidies after grid parity had been reached. Well, new PV now costs half the retail rate in Germany, and a new "guerrilla PV movement" is underway. You can add the word "solar balcony" to your vocabulary. The European Parliament already has. But there are still problems.

There's a new product in Germany everyone's talking about: small solar arrays, sometimes just a single solar panel, that you simply plug into your wall socket. The solar panel has an integrated inverter, and you use it to meet your own in-house "baseload." For instance, a single solar panel with an output of 220 W can regularly produce 150 W for several hours a day, enough to meet the demand of all of your household devices on standby and possibly even the refrigerator when it kicks in. The average German family of four consumes around 3,800 kilowatt-hours of electricity in a year, equivalent to a constant consumption of 434 W, so such a family could easily wipe out part of its baseload consumption with a single panel (and for those of you concerned about prices, 3,800 kilowatt-hours is equivalent to an annual power bill of €1,064 a year or less than €90 a month, meaning that Germans pay less for electricity than Americans do).  

The new product is especially attractive because it opens up PV to a new market segment; no longer do you need to own your own roof or lease someone else's – you just hang your solar panel on your balcony or outdoor wall and plug it into a socket.

Solarbalkon
Solarbalkon - In Germany, electricians are warning people not to install "solar balconies." Now, the European Parliament is also calling for the legal situation to be cleared up.  What are the actual risks of plug-and-play solar panels?
In Germany, electricians are warning people not to install "solar balconies." Now, the European Parliament is also calling for the legal situation to be cleared up. What are the actual risks of plug-and-play solar panels?
Landeley Betriebstechnik / Nicole Weinhold

Solar firm GP Joule sells a single 165 watt panel with a micro inverter for €450, and the firm says you can save up to €80 a year with it, meaning that the product pays for itself within six years. But a recent article in Germany's premier IT biweekly c’t points out how quickly that calculation can change. The payback time can foreshortened if retail rates continue to rise, but simply having someone come by to install the unit safely can cost €100, setting you back more than a year. And if your panel gets damaged at any point during those years, the investment never pays for itself. The problem is not just that children playing outdoors might knock off your solar panel with a football, but that the structure the panel is installed upon might not be designed to handle the weight, especially if there is a storm.

In the Netherlands, you can hook up as many as four panels with a total rated output of up to 600 W without further ado. Likewise, no one in the Czech Republic or Switzerland has any problem with solar balconies. "And we get swarmed at trade shows in India and Greece," says Toralf Nitsch, head of Sun Invention in Germany. The British-German solar firm launched its Plug and Save product last August, and it also comes with an optional battery. "It's just the German market that is slow," he says. "Really, Germany is the only country where there is an unclear legal situation."

For instance, German electrical association VDE has expressed its concern about safety; the power generator is behind your household fuses, so there is still power in your lines even if there is an outage. Furthermore, Section 49 of the German Energy Management Act says that energy generators must "ensure technical safety, and general technological rules generally applicable must be heeded."

Breaking the rules?

In March, Renewables International and its German sister organization reported on the controversy, and the VDE responded by stating that plug-in solar arrays do not follow the rules. Since then, the European Parliament has called on member states to come up with clear rules for solar balconies. The goal is clearly to make it easier for people to install plug-and-play solar.

Electricians are mainly concerned about laypeople hooking up power generators. The article in c’t sums up the legal situation quite well: if your power meter runs backwards, you can be convicted of fraud and tax evasion; but even if you get a new power meter that does not run backwards, you will probably be asked why you need one – and you lose any power you were not able to consume. And if your home burns down, your insurance company will in all likelihood refuse to pay until you have demonstrated that your solar balcony did not cause the fire. In other words, you cover all the risks.

Scare tactics?

Why is there all this concern in Germany but not elsewhere? The VDE says it is worried about power lines overloading and causing fires and points out that fuse boxes currently installed in households only work in one direction – from the grid into your household.

But André Steinau of GP Joule says the concerns are "scare tactics" and points out that his firm has been installing plug-in modules for two years, and nothing has gone wrong. "The power lines are designed to handle 20 A, and the fuses go up to 16 A, leaving us with 4 A of leeway. The cables don't start heating up until you exceed 20 A, but the micro-inverters in the panels only produce 1 A. Even if the lines are completely full, you still have 3 A of leeway." Steinau therefore calls on Germany to follow the Dutch example and allow solar balconies up to 600 W.

Sun Invention also does not understand the concern. "Our micro-inverters ensure that no pulsating direct current reaches the alternating current side of the fuse box in the house," Nitsch says. "We have demonstrated that our panels are fully functional and safe in hundreds of tests." And he says that people can prevent fires by following some simple rules. "It's important that any power-consuming devices hooked up not consume more than 2,500 W. And you also have to use the plugs we provide with our panels and not hook the product up to a power strip. And if you want to be on the safe side, you can switch out your 16 amp fuses for 10 amp ones."

Calling the experts

But the VDE doesn't think that's enough – they want people to call an electrician. "We don't even want lay people switching out fuses – that's a job for an electrician." And indeed, German law specifies that only trained electricians are allowed to tamper with low-voltage systems.

While the German organizations try to come up with a solution for existing buildings, Nitsch has a proposal for new builds: "Why don't we start installing a separate socket where people can hook up their own power generators? Then, any technical concerns can be handed over to architects and builders." (Sven Ullrich / Craig Morris)

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2 Comments on "Plug-and-play PV: the controversy "

  1. E Morris - 11.12.2013, 06:34 Uhr (Report comment)

    most modern mini inverter now closes down as soon as mains shuts down,or if unplugged,???or should do if compliant

  2. Todd Millions - 17.09.2013, 22:53 Uhr (Report comment)

    Why not fuse the inverters,before they connect to the plug in?This also would seem to me to make the more effeient freezers in particular,that don't need the constant draw too be more compelling in payback times.I can foresee bogus pr campains on the safety of these balcony installations.pointing out that the same grade of tempered glass used to enclose balconies,is used on the panels may be wise in anticipation.Use of flouroplastic glass fibre glazing(as per unisolar), wiser still.I await output comparisions of balcony mounts vis a via same panels roof mounted at various cloudy high latitudes,with eager anticipation cheers

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