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Author Topic: Easy Solar PV?  (Read 1775 times)

aspazatak

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Easy Solar PV?
« on: April 10, 2012, 07:54:08 AM »
I've been playing with the idea of building a simple solar PV system that uses micro-inverters on each panel (similar to Enphase) rather than a central inverter. What I want to try and do is see how inexpensively I can offset my pool pump usage with solar panels.  I know I can get panels for sub $1/watt, and I think if I build the inverter and put it in a NEMA box it'll be cheaper than the options currently on the market.  The catch is what I know about electronics I learned in the trial intro to electronics class.  I've been reading about micro-inverters and their applications, but would still need help with design. I want to build it so I learn from the experience, but am soliciting a contact to provide guidance.


Anyone interested in helping out?  I need to finish my hydroponic garden (also solar powered) before I  start this, but I figure it's worth asking at this point.

f00bard

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Re: Easy Solar PV?
« Reply #1 on: April 10, 2012, 08:26:47 AM »
I've been interested in micro inverters myself.  I have a TI dev kit for DC/AC conversion.  It used to be difficult stuff, but when you think about it an inverter is pretty simple.  The trick is just syncing up with the existing phase.  The kit I have is a reference design plus software.  Glad to bring it in.

Also, I know one of our members, Mike S, has done a lot of power supply work.  He could probably help us with any questions concerning that side of the project.

aspazatak

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Re: Easy Solar PV?
« Reply #2 on: April 10, 2012, 08:45:33 AM »
Cool, I have to go to Atlanta this weekend, but hope to start getting serious about it the weekend after that. I was discussing with a co-worker yesterday how to tie multiple microinverters together to get up to around 20 amps of 220VAC power and I believe they are connected in parallel, but all my experience in home AC wiring is single source and multiple loads. I've never thought about multiple sources and a single load being a home. So I'm a little unsure of myself when it comes to that type of connectivity. Makes sense to me in DC power, but never thought about AC that way.  Maybe one of the power guys can elaborate on it.

Bobsea

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Re: Easy Solar PV?
« Reply #3 on: April 10, 2012, 05:23:56 PM »
Are you going to use any battery back up.  Will this be stand alone or will you want to use grid power for the times there are no sun. You can not grid tie a homemade inverter of any type.  Micro or otherwise.  When I am done with the power racing car I would love to help.  I am a NAPCEP certified PV installer and would love to work on this project.

aspazatak

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Re: Easy Solar PV?
« Reply #4 on: April 11, 2012, 08:03:50 AM »
Well the idea was to grid tie it, but your news is a buzzkill..:)  Actually I'd still like to make my own inverter for the learning experience it offers even if I ultimately buy some to tie the PV panels to the house.

Is the reason you can't grid tie them due to lack of testing like UL etc?

Bobsea

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Re: Easy Solar PV?
« Reply #5 on: April 11, 2012, 05:35:56 PM »
Yes to be grid tied you have to get the OK from AHJ  the dreaded authority having jurisdiction which is the building inspectors and the electric company you use.  For the DIYer go stand alone.  You can still do most of the work on a grid tied system yourself as long as a licensed contractor will work along with you and you use UL approved stuff.  There are alot of high efficency devices that work great with a PV system, if you can go with DC powered stuff better yet.  Prices on micro-inverters should be coming down as more Mfg. start making them. :(

aspazatak

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Re: Easy Solar PV?
« Reply #6 on: April 11, 2012, 06:04:32 PM »
Yea, I've noticed PV panels are sub $1/watt and micro-inverters are slightly over $1/watt in individual units. I had thought about going with a DC motor for the pool, but the cost of the motor would extend the ROI on the system and as long as the energy I put back in matches the energy the pump uses the net is still $0 cost for running the pool and I can add more panels as time and money permit and gain more monetary benefit.