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Grid tied system..
By buck22, Section Solar Posted on Mon Sep 28, 2009 at 09:23:20 AM MST
Just need a little help.

Hello,
I would like to build a small grid tied system. When I say small I mean just a couple of panels. I have e mailed some places and I always get the hard sell.
I would like to know of any ready great places to buy equipment and also more info on a grid tied system. I'm new so all information would be great.
Thanks a ton,
Buck

Grid tied system.. | 8 comments (8 topical)

Re: Grid tied system.. (3.00 / 0) (#1)
by juddley on Mon Sep 28, 2009 at 01:08:45 PM MST

Hi Buck,

From your other post you are in the Mountains in Southern CA. The problem with Grid Tie here is they don't want to do Small Systems and a rule of thumb is 2 kw as a starter.... and even then the Cost/Payback is $0. With the CA rebates and if you are in SoCalEdison area (they also have a program currently) it may payback in Tax incentives.

Since your other post is regarding new Home construction, the cost of implementing is much cheaper on new construction. With the Rebates, New Construction, and a well insulated home it's very doable..... But it has be for the purpose of Going Green. If it's for saving money you may want to consider using separate systems RE/Grid. The savings with Grid-Tie is the elimination of battery storage. (Which I would want anyway)

I think an important first step is to do a detailed energy survey and get a set of house plans. A good installation engineer can work with those and give a detailed proposal with sizing/costs options. A good starting point is the WEB site of the Power utility you will connect to. From that you can get an idea of whether they will "Work With You" or not. Some say they want RE but do everything in their 'power' (pun intended) to discourage it.

Judd

Re: Grid tied system.. (3.00 / 0) (#2)
by imsmooth on Mon Sep 28, 2009 at 03:19:30 PM MST

If you are doing grid-tie the inverters are very expensive. Your break-even gets better if you max out an inverter. One or two panels would not be worth it. Looks at some Sunnyboy inverters and find the smallest one you want. Then figure out how many panels you need.
Jonathan

Re: Grid tied system.. (3.00 / 0) (#4)
by DamonHD on Tue Sep 29, 2009 at 01:11:54 AM MST

I have 3 identical strings (but with different orientations / shading) of 1.29kWp each on a SunnyBoy 1(.1)kWp inverter: in other words, when my installer added up on his fingers on toes it was better from a conversion-efficiency point-of-view (and presumably money too) to risk occasional sunny peaks where there was more power than the inverter(s) could use, but in return run them closer to their peak efficiency more of the time.

I've rarely/never seen evidence of the inverter(s) actually being saturated, so I think my installer was right.

Rgds

Damon
"Once you have licked the windows of freedom your tongue gets stuck."
[ Parent ]

Re: Grid tied system.. (3.00 / 0) (#3)
by Tritium on Mon Sep 28, 2009 at 03:37:51 PM MST

There are starter grid tie systems using 1 panel and a single enphase inverter as shown here:

http://www.wholesalesolar.com/enphase-solar-power-system.html

Thurmond

Re: Grid tied system.. (3.00 / 0) (#5)
by Ungrounded Lightning Rod on Tue Sep 29, 2009 at 04:09:39 PM MST

If you're looking for payback from solar, grid tie is not the answer (so far). Panel cost per watt has to go down by a factor of ten or so (or power prices up ditto) for that to break even.

Where solar actually pays off is when you're doing new construction in an area that doesn't have nearby electrification and it would cost you a couple tens of grand to run the power line to it. If that ticket is big enough to buy a sufficiently large system to run the house if you spend it on RE instaed of financing the utility's construction, the ongoing cost of maintaining the system and replacing the batteries periodically can come out ahead of the ongoing cost of an electrical connection.

But if you're going grid-tie you don't get the "didn't buy the power company a transformer and a couple miles of poles and wire" savings. Then your benefits have to come from somewhere else - like enjoying the hobby, feeling good when your lights are on while the power's out or when you think about how much fossil fuel isn't being burned to run your place, or more-green-than-thou one-upping the local Prius-riding yuppies at a cocktail party. B-)

Now (as others have already pointed out) if you do build a grid-connected RE system anyhow, you can go to net-metering. Then you can use the grid as a BIG set of "batteries" that can "store" your power for you. Your local battery bank only has to be big enough to cover outages (and if you have a mill to provide a smoothing load for gusts and to eat the storm power when it gets ahead of your dump load). (You can even go lighter than that, if you're willing to cut down to emergency loads only during an outage on a calm night.) With monthly net metering you can use the grid to store day power for night use and windy days' power for calm days' use. Go to annualized net metering and the power grid can even "store" power from sunny/windy seasons for use during dark/calm ones. Downsizing the battery bank might pay for the fancier inverter with the grid-tie option.

Re: Grid tied system.. (3.00 / 0) (#6)
by GaryGary on Tue Sep 29, 2009 at 05:59:36 PM MST

Hi,
I don't think the rate of return for grid-tie systems these days is quite that bad.

For example:
If you put a 1000 watt system in a good sun location (I used Albuquerque), according to PVWatts it will generate 1830 KWH a year.
If you pay 12 cents a KWH, thats $219 saving a year.

Prices of grid-tie systems have been dropping lately -- the rule of thumb used to be about $8 per peak watt, but I think its at least down to $7 now, and may be a bit lower. A friend of mine got a bid on a large system at $6 per peak watt. I'm thinking about installing a 2KW system using the Enphase inverters, and the total parts price (no install labor) is coming out around $5 per peak watt -- this includes wire, racks, disconnects, ...

So, if you use $7 per peak watt, the system costs (1000 watt)($7/watt) = $7000.
Take the 30% federal tax credit off that, and its $4900. State incentives might lower it more -- some states offer as much as 50% rebates.

So, ($219/$4900)(100) = 4.5% first year return.
That's not earthshaking, but a lot of people are investing in CD's at less, and its a tax free return and the return goes up as electric rates go up.

Its a good enough return that I'm going to do it:)

----------
On the original question of a small grid tie system, I think the Enphase system that uses one micro inverter per panel might be a good choice. You could put in a 1 panel, 200 watt system to start with, and add panels and micro inverters to grow it over time.
Here is a good description of a DIY installation of an Enphase system:
http://www.arttec.net/SolarPower/index.htm

Gary
Gary gary@BuildItSolar.com www.BuildItSolar.com
[ Parent ]

Re: Grid tied system.. (3.00 / 0) (#7)
by buck22 on Sat Oct 03, 2009 at 12:21:40 PM MST

To all thank you very much.

You have giving me some things to think about.

My biggest problem like I said is trying to get information. I also
didn't think that solar would be THAT expensive.

Anyways I will do some more research.

Buck

Re: Grid tied system.. (3.00 / 0) (#8)
by GaryGary on Sun Oct 04, 2009 at 09:19:05 AM MST

Hi,
I've been doing a bit more looking for my system, and have found some pretty good prices. One place to look is:

http://www.ecobusinesslinks.com/solar_power_kits.htm

The listed prices are as low as $3.38 a watt for the grid-tie packages.

Sun Electronics also offers some packaged systems for $3.48 a watt.

I've looked at these kits to some degree, and the major stuff appears to be there -- PV panels, inverter, disconnects, .... The racking systems they include are basically just rail, so you would likely have to make or buy something to support the rails. They don't include some of the odds and ends like wire, but it seems like its most of the cost. Fright adds some more cost.
With the 30% federal rebate and maybe some state rebates, this can make a system is not so awful on rate of return.

Gary
Gary gary@BuildItSolar.com www.BuildItSolar.com
[ Parent ]

Grid tied system.. | 8 comments (8 topical)

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