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Old 04-10-15, 11:31 AM   #1
gtojohn
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Default Getting a little solar to bring down my base usage

Although my energy usage has been down, partially from this site, I've been using a the Efergy kw meter, getting real time feedback on the whole house and its making me want to do something more. The house is pretty big, there's 4 of us and I can only cut our usage so much. Our base usage is about 16kw in the winter. That translates to quite a bit more for warm weather.
We are billed with 5 tier levels at 500kwh each. The top 3 tiers really ratchet up the rate. Thats great, i'm all for it, it'll help others want to conserve too. After doing a lot of research I've hatched a plan. If I hit tier 3 usage my rate after fees and tax is $.14 per kw and tier 4 is $.16. 5, I've never hit 5.

I figure if I go with a small enphase grid tie to cut back my base while the sun shines I'll get the fastest payback by keeping out of the higher tiers. I'm starting with at least 4x maybe 6x 240 watt sharp panels and enphase m215 inverters. The pay back before government rebates could be within 5 years if I do it myself. The enphase really seems the simplest for dyi, and expansion. I'm still gathering the pieces but really hope to get this going before it gets any warmer. 8 panels could really help make up for the a/c. The biggest hurdle I see is I will need to swap out my breaker panel for more circuits to add my enphase supply circuit.

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Old 04-10-15, 09:36 PM   #2
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Do it, and don't look back! I've got 4.4kW on my roof: (20) Enphase M215 + Evergreen 220W (poly) panels. The system generates 6MWh/yr at 26.8N. I designed and installed it entirely as a DIY system. I've already got another 4.6kW Enphase system that I will be installing sometime this summer using M215 + 235W (mono) panels at 45.8N.

Living in South Florida and having the sunshine essentially pay for my A/C to run year round made sense to me. If you need pointers, feel free to ask. It literally is as simple as you think, assuming you have at least enough space to fit a double pole breaker into your panel.

In my case, I paralleled the two circuits of 10 panels each from the second floor roof to the ground level using 10/3 UF-B (90C insulation), then used a Square-D QO 100A "sub-panel" to house two 15A breakers acting as a solar combiner panel. The solar combiner panel feeds a 30A double pole breaker in my meter/service entrance panel.

If you have to replace your main panel, be sure to get a 200A main panel. The NEC limits allowable backfeed into a panel, and you certainly don't want to have to upgrade the main panel again if you later decide to add another string of solar panels on the roof.

Consult with your local building officials before you start your design and be sure to ask if they will be changing which version of the NEC they follow in the near future. Also consult with your local electric utility and determine what additional requirements they may have to install a grid-tied PV system.
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Old 04-11-15, 12:09 AM   #3
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Where2 gave some great advice.

Solar panels have to be truck shipped so shipping under a pallet is the same price as shipping a pallet. If you have some big solar installer maybe you can buy a few panels from them. Sometimes they have someone that needs less than a pallet and add yours to the order cheaply or you can buy mixed panels.

Check out my build the first page I have some links to some well documented installs.
http://ecorenovator.org/forum/solar-...lar-array.html

Sunday we will have our solar running for two years now. We have made 36.2 MWh.
We are very pleased.

A solar install in TX should do very well.
Check out PVwatts if you have not already checked it out.
PVWATTS v. 1
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Old 04-11-15, 04:53 PM   #4
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Right now in the back of my truck I have 6 Sharp 240watt 60 cell panels. Purchased from a solar hobbyist. Apparently purchased from a closed PV panel factory in Tennessee, $185 each. He has more, once my initial install is going I plan to expand. Now for the excitement of roof mounting.
Something I've noticed from the 2 solar hobby guys I've met buying parts from, all super nice, happy to show you their set ups, tell you about their trials and tribulations, and give you more information than you ever wanted. A lot like this group here.
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Old 04-11-15, 09:29 PM   #5
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Your roof mount should be fairly easy, being between the two extremes.

I'm guessing you don't have to have structural engineering to say your array will still be sitting on the roof after a 3 second gust of 170MPH? (26.8N). Then to make my install more fun, I decided I didn't want to drill holes directly through my Decra stone coated decorative metal tile roof, so I have 102 mounts intended for use with a clay tile roof, and no crazy flashing of the metal tiles.

You probably also don't have to design for 100PSF ground snow load (45.9N). I'm really beginning to think a ground mount is in my future at 45.9N. I'm not sure I really want to put a series of holes in the roof, and then a pile of snow on top and ask if the house is still standing.
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Old 04-20-15, 09:16 PM   #6
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Installed 1.4k last weekend! Its a tiny amount of power, but its a start. Roof mounting brackets took the longest. I built my own racks from 4x super strut for $24 a 10' piece and 24x simpson 5" angle brackets for $5 each as well as 30x simpson mending plates for $.58 each. I have 5 enphase m215 inverters and 1 m250, curious to see any difference. I haven't finished the wiring beyond connecting the trunk line.
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Old 04-20-15, 10:46 PM   #7
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Nice you have to post the public link to your system once it is up and running.

Do you have to get inspected? Does you power company charge for the interconnect agreement?
Ours charges $100 for the startup and another $100 every system change you make.

It will feel so good when you start that it up and see the savings add up!

Last edited by pinballlooking; 04-21-15 at 07:54 AM..
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Old 04-21-15, 07:44 AM   #8
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Wooohoo, nice job!

I definitely wouldn't say 1.4 kWh is tiny though. That would cover half of my electric usage. I'd love that!
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Old 05-01-15, 03:15 AM   #9
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I managed to replace my subpanel last week and tie in the pv on saturday. I haven't had the time to sort out the envoy system monitor. It shows connected to the web but hasn't discovered my equipment yet. There might be an online step I haven't finished yet. I have seen the meter turn backwards, what a good feeling! I haven't had a chance to meter it during peak sun but I did read 3.3 amps output today, so 792 watts coming off the inverters. Since my Efergy power monitor can't tell which direction the ac is going it only shows the difference, 500 watts coming in and 500 watts going to the grid look the same. The main difference is the all daytime power peaks are down and if I manage to stage the big appliance run times I can put my little bit of excess to good use.
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Old 05-01-15, 07:42 AM   #10
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Do you have a total installed cost for it all?

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