Grid Tie. opinions and experiences please

[stag]

At first glance, grid tie seems like a dream come true. BUT!!  the concensus of opinion appears to be that cheap chinese units are crap or illegal, and stuff that is the real deal is prohibitively expensive for a small, DIY wind power set up. I don't wish to sell power to the grid but it would be nice to have a simple system that helped out with the bills.  Can it be done with chinese stuff or had I better stick with my battery bank. Note, I'm talking about the UK here.

[Flux]

I am not sure of the legal position. You will need an approved grid tie inverter as a very minimum. If you can get away with the other stuff it might work depending on your wind area.

If you have grid you won't save anything if you include batteries. If you value back up if the grid goes down again you might justify it but it won't "pay".

If you can use the grid as an energy store and use it to save power it works, there is no point in trying to sell back but you can use it for energy saving..

It all depend on what the initial cost is. In a very good wind area there is little doubt that you will break even on the cost of a grid tie inverter and probably see a profit.

If the rest of the equipment doesn't cost a fortune it may work but if everything has to be approved the whole set up will most likely never pay for itself in the working lifetime unless the wind site is exceptionally good.

To benefit from the feed in tarrif and other incentives you will need approved equipment and it will have to be professionally installed. To go this route on the cheap with Chinese kit is not likely to be effective.

Basically as I see it wind works in areas with exceptionally high wind speeds, it only works in other areas if you milk the incentives and it can still work then in areas that are crazy from the wind point of view but the initial cost will be massive.

Flux

[bob golding]

mastervolt do a 600 watt GTI that doesnt need any approval. you just plug it into a 13 amp socket. costs around £300. i worked out in cornwall with solar it would take about 4 years to pay for itself. i am off grid anyway so only thought about it for a friends house as i can get cheap damaged panels. still only just worth the trouble in my opinion. might be better with wind though. cant remember what the things are called offhand.

[DamonHD]

Bob,

Are you completely sure that plug-in GTI is actually legal in the UK (my memory of G83/1-1 says not)?  Do you have a link for that inverter?

(And only if it is legal *and* MCS approved is there any chance of getting FiTs, of course.)

I do wish that 'nano' generation could be done DIY, eg: http://www.earth.org.uk/note-on-G83-lite.html

I've stuck this under the government's nose more than once and I know it has been read and thought not necessarily lunatic, but I can't see it happening any time soon.

Rgds

Damon

[stag]

Thanks for the input guys. We are into self sufficiency, growing lots of friut and vegetables. We run 2 freezers,have electric water heating and cooking. A wood burner and chain saw takes care of space heating. So there is virtually no time when we are not using some power. Therefore, I am not concerned with feed in tariffs , just a little help with the bills. At present I am charging batteries effectively but don't have the equipment to measure the max output of the mill yet,so am gathering info so as to weigh up the options.

[thirteen]

I installed my solar control panels and applied for the tax break on my taxes. It was supposed to be 30% of the total cost the first year and 20% for the next year. I only have $5600.oo in it. I did have to get them a picture and diagram of it. I did also get to put my milage down and time of travel. So I ended up with about $7100.oo. They did not require a permit to install it but it needs to be inspected. Since I am way off the grid out in the sticks the electrical inspector said he would ok it if I opened up the panels and took pictures of the wiring and showed the ground tests and the batteries. I have an electrical repair license for maintence on crushing and hotplant electrical equipement. I have worked with him before and never had any of my work turned down. He is a common sense inspector. There is no grid power for 4-5 miles. But to get my tax break from the Feds I need his sticker on the side of my panel. $45.oo should get me about a $2100.oo deduct this year and about $1000.oo next year.
I thought I would mention this incase you can get a tax break for installing new indepandent system. I do not know what requirements are needed where you live. But they do not need to know everything we do.   13

[midwoud1]

Windmaster  GTI  500 Watt.
Possible 2 in parallel.
Input 35 - 150 Vdc
Output  230 Vac 50 Hz !!!!!!!

http://www.mastervoltsolar.com/solar/products/windmaster/windmaster-500/

Rgds -Frans-

[DamonHD]

From the manual:  "In some countries one single Windmaster 500 may be connected to an existing electricity branch circuit which is fused with 16 Amp. In other countries different restrictions apply. Please acquaint yourself with the local regulations on this issue!"

In particular, though it is G83-compliant, and is thus type approved for connection, I suspect that at the very least a Part-P competent electrician would be legally required to make the connection and on a permanent fused spur (ie not a 'widow-maker' flying lead with plug).

You'd also need to notify the local DNO (the people that run wires to your house, not necessarily your retail supplier) after installation, and they *may* order you to disconnect it if not done as above.

So... If you don't care about FiTs, then as long as you use G83 compliant kit and get it permanently wired in properly then you may be fine!

Rgds

Damon

[bob golding]

soladin 600 was the one i was looking at. as regards the flying lead i thought the whole idea of g83 was that you DONT kill yourself if you grab the plug. not that i want to try it but if it is g83 compliant it should switch off as soon as you unplug it. within a few milli seconds, the same as any other GTI.

[DamonHD]

G83 is more about protecting people working on the lines outside your house after a power cut then protecting householders pulling plugs (with the cut-off time seemingly ~0.5s), though I agree it could help.

But that's not the same as meeting legal requirements as to which equipment needs to be permanently wired in, and if so, by whom.

Rgds

Damon

[stratford4528]

It sounds as if you are producing power and storing it. If you are and using an inverter can you not have a change over switch by your fuse box. When you have power in your batteries change over when the batteries are flat change back or is that not feasible. 

[stag]

The windmaster 500 by mastervolt is the wind version of the soladin 600 solar grid tie. This may be a possibility if my max output turns out to be within its capabilities. I'm still waiting for an ammeter from ebay so that I can measure DC current. Charging 12v batteries at present,but have not had to buy any yet,so no money has been laid out for a battery bank. At present, just charging power tools , lamps etc with a small inverter. The house and land is rented, so I don't want to touch any internal infrastructure,but we have 2 waterproof sockets outside so the grid tie could be housed in my brick battery shed and plugged into one of these. Has anyone had any successes or failures with the chinese ebay stuff. The island protection feature should shut the unit down if the grid goes out but then the mill would have no load.

[Mary B]

The cheap chinese stuff has started fires. Stay away from it! Besides they are illegal to use and a good way to get disconnected from your utility.

[boB]

The cheap chinese stuff has started fires. Stay away from it! Besides they are illegal to use and a good way to get disconnected from your utility.

MaryAlana,  I collect this type of information.  Could you possibly point me to any links or stories on failures from cheap Chinese
stuff like this ?

Much appreciated !

boB

[thirteen]

I was a volenteer fireman for 5 years. We had several people that had off grid systems and some that were half and half.  They were required to have  sign on their mail box and one on their grid power supply and one on there power room or shed. The sign let us know where the power could be supplied from and cut.  The power company would supply the signs. If you did not the fine was around $3,000.oo and then they charged you for them to put one up I think it was about $250.oo. A couple of years before they did this they had a pole jumper (lineman)  get hurt and lost 2 fingers. The line was back fed with a short from an off grid system but there was no indication of any other power source. Do they require this in your area? Just a question, 13

[DamonHD]

13: my PV system is certainly decorated all over the place with signs indicating that wiring and equipment may be live until BOTH mains and PV are shut off, and I believe that that is a legal requirement (for just the sort of situation you describe).  Sorry to hear about the bloke losing his fingers.

Rgds

Damon

[fabricator]

In the US most power companies charge you a monthly fee for your connection, plus initial permits and extra wiring and equipment costs for exterior disconnect switches, if you can make enough power to pay all this stuff off then you might come out ahead, most people cant, you have to do the real numbers.

[DamonHD]

Here (UK), no specific fees or permitting that I've encountered, at least for small systems, beyond having stuff wired in and signed off by someone competent.  I've put up 3 grid-tie PV systems now (2 houses and a local school) and the general lack of red tape has been amazing.  Indeed, after the school effort and an annoyance that I encountered doing it:

http://www.kingathelstan.kingston.sch.uk/for-parents-and-carers/latest-news/2012/ed-davey-opens-king-athelstan-s-solar-system/

the UK FiT rules got simplified a little for everyone in the future attempting a similar 'community' install, which I hope to take advantage of working on a much bigger forth system!  B^>

Rgds

Damon

[stag]

Seems that the UK is more amenable to this stuff than the USA,but from the above comments I think I will bide my time ,using a few batteries and an inverter. In addition to some of the above advice, my gut reaction has been to avoid the cheap chinese stuff and I have a strong aversion to spending money anyway . Keep it coming guys. I'm learning something every day. QUESTION. When connected to a battery, the voltage is held down, but what happens when hooked up to a grid tie. Does it just take everything that the mill can throw at it( open voltage)??

[fabricator]

The UK is not owned by big oil.

[Flux]

" QUESTION. When connected to a battery, the voltage is held down, but what happens when hooked up to a grid tie. Does it just take everything that the mill can throw at it( open voltage)?? "


The grid tie inverter can be programmed to load the blades so that they run at ideal tsr at all wind speeds. This effectively means that the voltage of the input rises directly with wind speed and the power absorbed from the blades rises as speed cubed.

With direct battery charging you start with the prop running too fast, then it comes about correct for your most common wind speed and comes down towards stall in the higher winds. The energy capture is a lot lower than the ideal loading of a gti inverter. The Classic lets you do the same thing for battery charging by letting the volts rise with wind speed. You get a better match to the prop and you avoid the very high I^R losses due to high alternator and line current in high winds.

You can't in fact load a machine at its open circuit volts as the prop is in runaway mode and is dissipating all its power supplying the aerodynamic losses. The ideal operating speed will be at the peak of the curve between run away and stall and will typically be near half run away speed so you will be loading at something like half open circuit volts.

Flux

[stag]

 Flux. Thanks for the above Info.Very helpful.   Fab.Since joining the forum I have been amazed to hear of the  tight restrictions in the USA, which is much less denseley populated than the UK. What happened to the land of the free?. Sorry! a bit of topic. Didn't mean to start a political rant.

[thirteen]

first Lawyers came along, then greed took over and common sense disappeared then the government got bigger  and bigger.  13

[Mary B]

One of the fire stories was told by someone on here who owned one. He caught it in time before it fried the entire house.

[fabricator]

Yep, I remember that one, he was pretty hot on those things till one almost burned his house down.

[WindyOne]

The grid tie inverter can be programmed to load the blades so that they run at ideal tsr at all wind speeds.

Flux,
For the typical three blade wind turbine, is the ideal TSR roughly constant for all wind speeds from cut-in all the way up to max power ( furling ) ?

 

[Flux]

Good question. Yes in theory the tsr is determined by the pitch angle and the blade chord width and should be constant.

Having said that I do find that the best tsr does fall in the higher wind speeds ( 25mph plus) with my blades. The drag rises with speed and with a tsr of 7 you are getting up to quite high tip speeds, when it becomes noisy you can reasonably expect the drag to be rising rapidly.

I find that my blades with tsr7 tend to be happy running at nearer tsr5 in high winds but I have never tried to carefully copy any specific profile. It is likely that choosing a suitable profile and making it exactly will bring benefits in high wind where drag is more of a factor.

I think that if you are working without mppt there is absolutely no need to spend a lot of effort making exact profiles. When you have achieved mppt and overcome the serious matching problem then it might be worth looking at profiles if you use the higher tsrs. Probably starting with tsr5 you will be limited in high winds by other factors before the drag affects the matching.

Just my thought, it would be interesting to see what other people using the Classic have found.

Flux

[stag]

Ebay is awash with the cheap chinese grid tie units, mostly for solar, but many claim to be for wind and solar,but seem to be the same units. I wonder why they fail. Do they not live up to their rating? Some say use a buffer battery when hooking up to a wind turbine . others say never connect to a battery. another accepts 3 phase AC input,meaning that the rectifier is in the box, which I don't like.  All paints a confusing picture, and ,of course many people ate temped by the price.

[fabricator]

I'm not Flux, but no TSR is the ratio of wind speed to blade tip speed, as the wind speed rises the blades become less efficient and more wind slips through the blades and is not used so the ratio goes up as wind speed increases.

[Tom Sullivan]

In the US most power companies charge you a monthly fee for your connection, plus initial permits and extra wiring and equipment costs for exterior disconnect switches, if you can make enough power to pay all this stuff off then you might come out ahead, most people cant, you have to do the real numbers.

When I installed my first wind turbine (a Prairie Turbine), I went grid tie with WE Energies.  There was a $100 application fee and some reasonable equipment requirements.   I was able to make my own signs, and they were NOT done yet when I had my inspection, yet they still approved it.  The inspector drove up from 125 miles away, spent a couple hours looking over the system, testing it, filling out a bunch of paperwork for HIS company and approved it.  No inspection fee, no monthly fees and they installed a special meter to monitor my electrical generation.  I was able to bank any excess (like that ever happened).  When I removed the unit and no longer needed the "grid tie" meter, they removed that for no charge as well.  Point being, not all power companies in the U.S. are unreasonable.

Tom Sullivan