GTI DIY what happened?

[(unknown)]

What happened to the DIY Grid Tie Inverter project?  It seems like there was a lot of talk but did anyone finish this?  

Has anyone ever cracked open a Grid Tie Inverter?  Is there any documentation around?  I'd love to see what's inside one of the Xantrex or SMS boxes.  

[Kevin L]

Their is no DIY GTI, at least in the US, Canada, or any other industrialized nation.  Not that the project couldn't be made by an individual.   The GTI is one of the last high priced items that block the average guy from selling without a major investment.  If you can DIY and can get UL approval, as well as Utility certification to attach to the grid, Let me know.

Kevin L

[RatOmeter]

I'll let ibedonc speak for himself, but I think you're being a bit impatient.  ibedonc has several functional building blocks in his inverter design and is making excellent progress for an after-hours project, but I don't believe he ever intended it to be grid-tied. There has been some talk here and more in the IRC chat channel (#otherpower on irc.anotherpower.com) about grid-syncing possibilities but, as far as I know, it's mostly mental excerise at this point.

Some facts about grid-tie:

   . Commercial grid-tie inverters are expensive.  Even with liberal net metering policies, it's hard to make them pay for themselves.

   . There is very little chance that a DIY grid-tie inverter is going to get UL/CSA/FCC approval.  If someone here were to release plans or even a kit, they'd need to emblazon notices everywhere to the effect of Educational Use Only! Do Not Connect to the Grid!

   . On a similar note, it would take a least a healthy, 6 figure budget for R&D, testing and various approvals before a finished model could be sold.

   . Make a serious inquirey with your local electric utility about what it would take to connect an RE system to their grid. I think many of you will discover that, while it is theoretically possible to do so in your area, in actuality there are many roadblocks, intentional or otherwise, that make it impractical.

   . Guerrilla or unauthorized grid-tie like you may have read about in HomePower magazine is fraught with risks... even more so with a DIY/homemade unit.

After all that negativity, here's my opinion. I think we will see a DIY inverter design with [optional] grid-tie features come out of this group... but it won't be for a while, so be patient. Also, it looks like one of the most practical applications of such a design would be for your private grid; to sync your wind/PV/hydro fed inverter output to that of your bio-diesel fed genset, as an example.

[TomW]

Rat;

Very good rundown. Funny how the impatient are also the uninvolved. Don [and others] have gotten a good ways on this project to date considering the lack of an R&D budget and the fact that there are about 5 parallel projects running like dc to dc converter, the generator low speed booster, etc.

I want mine now, with a side of blue cheese, thank you!

Cheers.

TomW

[thunderhead]

On a similar note, it would take a least a healthy, 6 figure budget for R&D, testing and various approvals before a finished model could be sold.

Having developed approved equipment for connection to the telephone network (a similar problem in terms of approvals and safety) I think you could manage it at home for a four figure budget, if you really, really worked hard on cost.  But the first of those four figures might be an eight or a nine.  Approvals houses tend to be expensive.

Either way, though, that's rather a lot of money to spend on something that's then going to be given away. :-(

However, nowadays the whole point is becoming academic - a new raft of UK legislation (a thing called "Part P Building Regulations", in force for all of 23 days and already reviled by electrical and electronic engineers throughout the country) makes it illegal for amateurs to install grid-tie without getting all their work inspected by the local council.  I'm sure similar legislation will be coming to a legislature near you real soon now.

Nanny knows best!

[(unknown)]

TomW,

I'm sorry if I sound impatient or uninvolved and that you misunderstood me.  I was simply asking what the status of this project was and where I could find more information and who to contact.  

I didn't see any information about the GTI on that rerenewable.org site.  Perhaps you can show me where it is and give me the email addresses of those currently working on the DIY GTI.  I'm sure I can be of some help, I am interested in the roadblocks others have come upon.  

It sounds like if there are 5 different projects and talk of a booster then there are 5 different applications and 5 different goals in mind.  I'm pretty sure the Xantrex and SMS boxes don't use boosters or have a need for them.  However if you are trying to power your house with your wife's exercise bike or a car battery then you may need a booster.  

Peter H

[RatOmeter]

To get info on what's been done so far, look back in the diary postings here. Also log in to the IRC channel #otherpower and irc.anotherpower.com Don C is usually logged in and happy to explain what he's done and planning to do.

Basically, he's finished building a full sine wave inverter output section and drive/control section.  Last I knew, he was working on a DC to DC converter design to act as a front-end to the inverter. The idea there is to allow a wider range of usable input voltage to feed the inverter.  As an example, 12, 24 and 48 volt inverters each accept a fairly narrow range of input voltage around their rated value.  What if an inverter could accept the entire range of say, 10V to 60V?  Or 20 to 100V?  I suppose you get the idea.

From a purely electronics perspective, adding a DC-DC converter front-end adds some inefficiency (more losses). But it has the potential, depending on one's energy input resources, to increase usable energy production by far more than its losses. Let's take a 24V, grid-tied wind mill as an example. To keep it simple, we've got no batteries.  A stock inverter might accept an input from around 18V to 30V.  In low wind conditions your mill might be putting out 8 to 16V... too low for the inverter. In high winds, it might put out 30 to 50V; too high for the inverter.  A DC-DC converter designed to handle your most common range of supply V might be able to feed your inverter a steady 24V across all or most of that range.

A DC-DC converter could also be used in battery charging applications to reach "cut-in" or charging voltage sooner... only got 10V? The DC-DC converter could boost it to 14V (at a lower current) and you're charging. Ideally, the circuit would switch itself out when the source voltage is in charging range, to increase the efficiency.

The "boost" circuit that jacquesm is working on (suggested by Victor and apparently done in production by Bergey) takes the DC-DC boost converter concept and uses the windmill's generator coils as a part of the boost circuit. It lowers the cut-in speed by boosting whatever voltage is available to charging level.