Guerilla PV Time

'Guerilla PV' is bodger slang for the connection of unregistered microgenerators to the power grid.

You can't earn any FIT payments for it because it is an unregistered generator and has no MCS certification.  You may get into trouble with the energy supplier and/or network operator, as your import meter may run backwards or may set an anti-tamper fraud alarm built into the meter.

Being unregistered, non-certified, and not installed by a 'qualified'  person (electrician), the network operator would have cause for alarm.  Is this thing safe?  Will lines men working on a failed power line in your area get an unexpected shock - literally?

So why would you want to do such a thing and what of those companies claiming to sell a simple plug in solar panel that anyone can install without professional help?

I decided to find out more, and in true bodging style, "Just bosh one on there and see what happens".

I managed to acquire an example of one of these kits.  They normally sell a whole thing with a PV panel with a micro inverter bolted on the back, a PV mounting kit and a long AC cable that ends in a RCD plug. In my case, I already have a whole load of PV panels, so only needed the micro inverter and AC cable.

The idea is that the kit just plugs into a normal ring main 13A socket somewhere near your garden or wherever the solar panel is.  The cable kit was well made, using fully waterproof connectors.  The micro inverter is 'micro' because it only accepts power from one PV 35V (72 cell) panel of up to 240Wp output.  So for a typical 4kW installation, you'd need about 16 of these things, one for each panel on the roof.

But if you've only got one panel, then it's a pretty neat idea.  Your solar panel literally just plugs into the AC as if it were an appliance.

Now, I don't want to get anyone killed, so I looked at what the kit is composed of.

The micro inverter is one of the well respected Enecsys models that comes with UK G83/1 certification for anti-islanding.  This is the important part, as without this it is illegal to connect to the power grid and may be extremely dangerous.  Beware the cheap Chinese grid tied inverters on eBay with no certifications!

The Enecsys inverter is has full galvanic isolation of the DC side from the AC side, to prevent high voltage AC leakage to the solar panel frame (bearing in mind this panel could be on your lawn).  The DC connections are made by MC4 connectors, so it's waterproof and somewhat foolproof in connecting the panel up.  The inverter has bolt tabs so it would just bolt to the back of the panel.

The issue of the potential for live AC appearing on the AC plug pins is countered by a RCD breaker plug.  This has to be manually reset to 'on' each time you plug the panel into a wall socket.  If the mains power fails or you pull the plug out of the wall socket, the RCD breaker is of the type that immediately clicks off, isolating the AC plug pins from the inverter output.  It can then only be reset to the on position by plugging it back into a socket and pressing the reset button.

So... Seems safe enough to connect to the grid.  It doesn't output enough power to cause a problem for a mains ring circuit (only up to 225W for the 240W input model) and has adequate certifications and disconnect provisions to prevent it being a danger.

But what of the other issues with it being unregistered and not capable of earning FITs (as it's not a MCS qualified install)..?

Without MCS certification (for the installation) or registration on the Ofgem microgenerators register, you can't claim any FIT payments for generation or export of your solar power.  With PV as cheap as it is now and the cost of the Enecsys having come down to under £100, maybe you don't need the FIT payments.  It will take longer for the kit to pay for itself, but it will reduce your electricity bills a bit (remember it only puts out a maximum of 225W of power in daylight hours).  Most people use the bulk of their imported electricity in the evening, so the plug in solar isn't going to help reduce bills there.  But a fridge freezer uses about 0.4kWh during the main daylight hours from 9am to 5pm.  It only has a working load of about 125W, so a single solar panel could do that much.

Then there are the other leeches around the house.  It took a lot of work for me to root out all the little things around the house that use power when you're not looking.  Classics are phone chargers, radio DECT phones, cooker clocks, gas boiler controls... A single 200W solar panel could negate all these leeches during daylight hours as well.  There wouldn't be much left over to export to the grid and a lot of the time it wouldn't cover all of the load, but it would reduce your background consumption bill.

So there's a case for it (maybe a bit shaky on finances but a case for the environment).

Getting into trouble with the energy supplier or network operator is another thing.  When plugged into a home without a registered micro generator, the existing electric meter may do one of a few things...  It could run backwards if it's a mechanical disk type of meter.  This 'unwinding' of imported electricity is illegal and counts a fraud or theft of electricity, same as clocking a car to make it look like it's done less miles than it really has.  You are stealing the energy companies money.  This is because you used the mains at night (winding the clock forward) and then gave them back the energy in the day when you weren't using all of the solar power (winding the clock backwards).  But you still burned their gas, coal, nuclear, or whatever fuel in the evening.

Most meters are being converted to LCD digital ones.  These can't run backwards.  But some do detect illegal reverse flow and will set an alarm that the meter reader will see when he or she visits to read the meters.  They may accuse you of electricity fraud.

Some meters get around the issue by counting up even when the power is going backwards (solar power is being exported).  In that case, they don't care that you have an unregistered generator but you would be paying the electricity supplier for every unit of electricity you gave them!  Your solar generator would actually increase your electricity bill rather than reduce it!

Next time... Connecting up this thingy and testing it on my guinea pig house :D

Un-FIT for Purpose

Another epic fail spotted today on our travels.

This was taken at 10.25 in the morning today... Where's the Sun in this picture, children?

Yep, that's right... it's at right angles to the solar array that some PV company has talked these folks into installing on an almost west facing (250 degrees) roof with the promise of massive returns on investment in the rush to beat the FIT rate downgrade last week.

This array was installed back in early November, just after the announcement that the rates were being slashed to 21p per kWh.

The one thing that should be applauded from the "rent-a-roof" PV mob is that they never agree to install on a east-west roof because you just don't make the money on such an array...

Other companies are happy to take your cash and install wherever they can.  The fact that it will take 20 years to pay back instead of 10 isn't their problem.

Bad Installs

As PV has been more about a "rush for gold" than producing useful energy, sometimes the allure of adverts and salesmen promising future returns of 10-15% in exchange for £10,000 of your hard earned cash today has lead to some questionable installs.

What's wrong with these installs, anybody?

Can't see the PV for the trees...

This one doesn't look so bad...

 

But what's that on the roof in the middle of the array?

So when the trees aren't shading the array in the afternoon, the sewer vent is shading part of it all day. They've installed the worlds most expensive sun dial...  At least the pipe will cast its shadow in the gap between the panels at 1pm (high solar noon in BST time) for the maximum power.  It will just reduce power output from the panels left and right of it from dawn to 12.55 and from 13.05 to sunset.

Generating Boost!

After missing out at the police auction in Bristol that was selling loads of recovered stolen PV dirt cheap, and missing out on some other auctions on line, I got lucky this week...

Eight 80-85W mono panels (650Wp) for £940... £117.50 each!
Two are 85W models (a BP and a very old looking GB Sol) and the rest are pretty new Chinese "Klearskies 2000" 80W models.  One had a load of garden fence paint splashed on it but an hour with some water and the Japanese "magic sponge" soon got rid of that.  Quite a feat, considering the glass is textured.

Now all I have to do is figure out where to mount them. :D

Strange as it may seem, I'm thinking of selling one of them, as that way I'll have an even number of 80W panels overall.  I'd only gone on to eBay to look for one panel to match up to the odd panel I have on the garage (I bought 5 panels last time).  Although I could use all eight, it would leave me with an odd panel again and it's too much of a temptation to buy "just one more" to make it an even number.

If I sell one, then I won't have that itch to scratch.

The guy was selling them to pay for his MCS / Part P training and then he'll do his house with a proper grid tied array as his exam install to get certified.  So now I'm sponsoring PV installers to get through college and do things properly by bodging my own system...  There's an irony.

He donated the suspicious 600W Chinese GTI that he'd used with this lot at the back of his garden.

I had a quick look at the innards and was glad that I did.  A capacitor on the output display power supply had swelled up and burst.

If magic smoke hadn't already issued forth, it soon would have.  As its only the Watt meter on the output and not part of the inverter itself, I bodged on a similar capacitor (but alas too small to make the meter work, but safe enough to make it not work reliably, if that makes sense).

An initial play with it in the garden yesterday showed that the inverter works, sort of.  I hooked up two 80W panels in series (the inverter works from 28-52V DC) and it made some noise and a plug in AC meter said something like 40W output (it wasn't sunny).  But then it sort of stopped altogether and restarted if I turned the DC off and on again.  Not sure if this thing works properly at all (or ever did...).  But as he gave it to me as a freebie, it can't hurt to play with it a bit.  On the other hand, he did mention that he used to have a 1kW one, but it exploded.

It has some appeal though... plugging in maybe just 80W of grid tied power to offset the base load that I can't get off grid.  I could use the old pair of 40W Kyocera panels on the garage and just put the GTI in the garage, plugged into the spur there.  I've some leeches that can't go on solar power (like the clock in the electric cooker, the central heating boiler, and so on). With a little bit of grid tied power I could null most of that energy import out without losing power to the grid (and I can't get paid for or worse, the import meter may count up even when power is flowing out of the house).

Of course the next thing will be arguing with the FIT bods about having expanded my DIY system. They may throw their toys out of the pram and kick me off the FIT scheme altogether (fine by me) or they might agree to pro-rate the kWh payments to exclude the additional capacity. I think they are already calculating it wrong for my existing system; I got my second payment a few weeks ago (only the second statement though as I didn't get approved until December) and it doesn't look quite right.

I'll also now have too much PV for the 60A Tristar controller so I'm going to use some of these panels on a E-W system. I'll get rid of the mickey mouse 12W & 15W amorphous panels and use the new ones to boost morning and late afternoon production, as off-grid needs a long flat power curve rather than lining all 2400Wp up at the noon sun and over loading the controllers and battery. I can't even use 2400W as the immersion heater is geared down to just 650W. But it will mean that I can use that 650W for longer than before and run other things like the fridge longer without hitting the battery at all.

It might even be time to bite the bullet and get a roof rail kit and talk to the BC bods about allowing me to install this kit on the roof, where it belongs.

Made in Japan (part 2)

This time we're in Miharu in the prefecture of Fukushima to the NNE of Tokyo by some 200km.

If you keep hitting (+) on the map it will zoom in and show Miharu (eventually!).

My father-in-law's house has two arrays on the South and West facing roof slopes and luckily even though it is in a quite steep valley, the valley runs East to West and his house is on the North side so it gets a fair bit of sun even in the winter.

The panels are made by Hitachi and are their newest hybrid crystalline amorphous type that have layers that give excellent wide spectrum responsiveness on cloudy days but the high output of crystalline panels on sunny days. The Sharp ones used on the house in Tokyo were a common crystalline type. On the South roof there are 18 panels and another 13 on the West roof.

All the power conversion kit is made by Sanyo.

As the array is split into unequal strings of 18 and 13 panels, they work at two different DC voltages. So outside on the wall is a voltage converter / combiner that converts the two different DC supplies into one at a common voltage that then goes into the inverter indoors.

A single DC cable goes to the power conditioner in the house where it is converted to mains. It's a less elaborate unit than the Sharp one and just has a single display that toggles between current kW output and the lifetime kWh generated. The information plate says it is rated for 70-380V DC input and 5.5kW output at 200VAC with an efficiency of 95%.

Outside, the utility company has fitted two digital electric meters, again one for power used and another for surplus power sold to the grid.

The inverter appears to be putting out 200V rather than the house 100V, so either it's designed to be split phase (100-0-100) relative to earth or it actually doesn't feed the house directly but just the grid through the separate meter so that the household usage bill is offset by the generating credits.

My father-in-law said that in the summer and up until September it generates a net surplus to the household requirements but by November it doesn't quite make enough to completely offset their usage.  On the clear sunny day shown here, the inverter reported making 3.0kW for a short while around mid-day but 2.1 to 2.6kW for the bulk of the day. The sun was quite low in the sky even at noon and as it moved round to the West, the output declined a bit.  In summer it was probably ok with the sun much higher in the sky and on cloudy days it probably doesn't make much difference either having part of the array facing west.

Another novel feature of their house is a Sanyo air source heat pump (ASHP) that heats water by extracting heat from the outside air (usually hot and humid). Using a sort of reverse air conditioner it pumps the heat into an insulated hot water tank. 

It uses about 60-70% less electricity than a resistive heater. The Japanese call it an Eco-Cute. It doesn't mean "cute" though... "kyu" is a kanji in Japanese than means "to heat water". The difference between an ordinary air conditioner compressor and these water heaters is that the refrigerant is at a much higher pressure in this system to more efficiently extract heat and it's only in recent years that they've been made small enough and cheaply enough for home use.

Inside the house is the large hot water tank and compressor. A digital display shows the water temperature and how "full" the hot tank is as a bar graph.

The system also controls the heating of the bath to a constant temperature - very important for Japanese.  You take a shower and wash and then sit in the tub just to relax and get warm while the system cycles the water.  You could sit in it all evening.

He also had the kitchen refitted and they changed from a gas hob for cooking to electric induction.  This wastes a lot less energy (95% of the energy goes into heating the pan rather than the hob or the air) but did have the drawback that they had to replace most of their cookware.  Induction hobs only work on ferrous metal pans, so the typical aluminium or stainless steel with copper bottoms don't work well.  As they generate quite a large surplus of electricity, it made sense to change from gas to electric for cooking.

Made in Japan (part 1)

It's not just me in my family that has solar power, no sireee.  It was actually my in-laws that started things off.

My wife is Japanese and her sister lives in the suburbs of Tokyo.  Back in 2008 they installed a grid tied 3.07kWp Sun Vista system by Sharp.  

Sharp call the inverter a "power conditioner" and it has a control and info panel near the utility breaker panel indoors.  It lights up different colours during the day to indicate the power level.  Blue means the system is generating a surplus and is selling electricity to the grid and yellow means it is generating but grid power is being used as well.

The panels are mounted on both sides of the roof but the slopes face sort of east and west so one half of the array is always sub-optimal. The sun doesn't make such a low angle in winter in Tokyo when compared to the south of the UK so the variation of day hours are less extreme and Japanese Autumns and Winters are characterised by clear sunny days (very unlike the UK). In the summer the sun goes mostly directly overhead so it's not such a problem.

Their house is the one at the back of the white one - you can just see the panels on the roof.  The houses are terraced back to back.

The installers mounted the inverter on the outside wall and then ran a wire to the remote control panel inside.

The mains is fed to two meters outside that the utility company installed.  The digital one on the left measures grid power drawn and the old school mechanical one on the right measures solar power sold to the grid.

The remote panel in the house displays an estimate of power being generated as well as the proportion being used or sold and the lifetime kWh. Flicking through the menus you can pull up generating history graphs for the last hour, day, week, or month.

It's about 11am in this shot and it's just started to make a surplus now that we are done with breakfast and have stopped using the kettle.  The sun is a bit hazy today. 

They tend to sell a lot of power during the weekdays when they are out at work but then buy it back at the weekends when they use the air conditioning and clothes dryer.

The whole system is a kit made by Sharp but a local installation company fitted it.