Montana grid-tie PV installation: questions

I live in a small, rural community in Montana and I'd like to plan a grid-tie PV installation this fall, complete the installation of the inverter this winter and PV panels next spring. What I'm running into are a bunch of "expert" installers in this area that want to sell me $30000 worth of stuff that's basically overpriced. If I can manage this project myself, I think I can save A LOT. So, I'll fill-in a bit of my background, the project I'd like to work on, and then lead into some questions.

I've installed off-grid PV and wind systems myself for about five years where I work in some pretty harsh mountain environments. At home, I've done most of my home wiring myself, though I'm not a certified electrician (this is legal in Montana.) I have a BS in electrical engineering, though I won't even pretend that makes me a qualified electrician. In other words, I'm an amateur with enough knowledge to make me dangerous.

In Montana, Northwestern Energy offers 1:1 energy credits on alternative energy. So, for every kW I produce and dump on the grid, I can draw a kW back later for free. This means NO BATTERIES NEEDED. I think that's huge - installing and maintaining batteries is a huge headache. In fact, most PV installations in Montana are done this way. So, this means I just need to install a grid-tie inverter (I won't do that myself), PV panels (this part I will do), and all the wiring and connectors. The panels will be roof-mounted, no tracker. For one, I don't have room for a tracker and second, I have a nice exposure on the roof for panels.

I'd like to start by installing a 4kW or 5kW inverter this winter and getting a main panel on the house converted over to use it (we actually have two panels in the house, both wired into the main.) Then, next spring I'd like to install 1kW worth of panels. Then, maybe next fall install another 1kW. PV prices are consistently dropping and I don't see any reason to install all of the panels at once. We have modest energy needs, and since we dump it all on the grid, I only need to plan for our average use as averaged over the entire year. So, a system like this looks pretty nice (though I'll probably buy the pieces all separate so I get 1kW to begin with):

Sharp 1792w Kit, 224w Poly Panels, Fronius IG 2000 Watt Inverter. (Link to NAWS competitor removed - 'Coot.)

So, the questions:
1. Like I said, I probably don't want to buy that kit. However, it has all of the connectors and everything else I need, so in that regard it saves me piecing that together. Am I really saving myself anything by piecing the parts together?
2. I've been looking at Evergreen PV panels. What's everyone's opinion of those?
3. Anyone know any electricians in Montana on the list certified by NW Energy to install grid-tie inverters?
4. Does this start-small-expand-later approach sound reasonable? If not, why not?
5. I've noticed that pricing on panels seems to vary from season to season. It seems like they're most affordable in January. Is that true or am I just smoking crack?
6. Is there a nice wiring and connector kit I should be looking at? It seems like with the right connector kit it would really make installing the panels easier. Is this stuff standard? Or vary from panel manufacturer to panel manufacturer?
7. Yes, I've considered wind. I don't like turbines for many reasons, so let's not discuss them. (Loud, mounting and wiring is hard where I live, we have VERY STRONG winds, and ongoing maintenance concerns me.)

If this all works, I might consider turning this into a side business. So far everyone in Montana I've met who installs solar hasn't been pleasant to work with. They insist I need to install 6kW of panels and that installing a grid-tie inverter will cost me well over $6000. If I could do this on the side for some friends who are also interested, I think I could have fun and make a few $$.

Comments

  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Montana grid-tie PV installation: questions

    If you want to start small and grow big there's a couple of issues that come up. The first is that next year you may not be able to get the same panels you bought this year. The things change quite quickly, and matching different panels can be a bit of a hassle. The other thing is legal permits: depending on your AHJ adding panels later may constitute a change to system design which requires re-permitting and re-inspection. Check with the local authorities on that. You'll also have to look in to your utilities specific grid-tie/net metering plans. It can be a nightmare of complexity.

    Evergreen panels are well thought of, except in as much as the company has up and hied out of the U.S. and taken its production with it. There's some extensive reading about that whole situation on the forum somewhere if it concerns you.

    There can be some advantage to assembling your own and not buying a kit. Getting the right stuff for your particular install instead of whatever comes in the package for one thing. Most panels, btw, use standard MC4 connectors.

    You'll want to try a few system designs out on PV Watts to see what you can expect for your area:
    http://www.nrel.gov/rredc/pvwatts/

    It will give you a good idea of what to expect year 'round.

    Our host NAWS has some sample grid-tie systems here: http://www.solar-electric.com/grtiesyexqu.html

    That will give you some idea of what to expect financially.

    Inevitably some people will suggest microinverters, especially from the convenience of building up a system. Perhaps you should look into that possibility as well.
  • solarvicsolarvic Solar Expert Posts: 1,060 ✭✭✭✭
    Re: Montana grid-tie PV installation: questions

    Mark is right about not bieing able to get the same panels later on. I fell into that trap and had to get 2 separate inverters. I accumulated most of my stuff over a period of 3 or 4 years before I finally quit precrastinating. I ended up with 2 different brand and sizes of panels and had to use 2 separate inverters. If I would have got all the panels at 1 time I would have only needed 1 larger inverter. Still worked out for me as I think I have 2 smaller inverters that didn,t cost that much more than I big one. If I had it to do again I would buy all the panels first and then get an inverter later if I couldn,t get everything at once. Another thing I would get an inverter that can go to 600 VOC instead of the one you chose that can only accept 500 Voc. You should look at some string charts for different inverters and decide what voltages and Amp panels you like that are a good buy. I like kyocera. I have them and Sharp. I noticed you picked sharp. I think my kyocera outperform my sharp panels. Could be the inverters too. The sharps are on A fronuis ig-3000 and the Kyocera are on a fronuis 3.1 plus which is a newer model and can take 600 voc. verses the ig-3000 @ 500 voc. :Dsolarvic:D
  • System2System2 Posts: 6,290 admin
    Re: Montana grid-tie PV installation: questions

    Those are good tips, it looks like I'm on the right track.

    So, running the NREL calculator gives me a value of yearly average of 4.35 kW/m^2/day. Assuming a 2kW array with an efficiency of 80% looks like 2 * 4.35 * .8 = 6.96 kW per day of output on average. Opening my last electric bill, we're using on average 20kW a day right now... so I probably have this a bit undersized. Hm.

    As far as mixing and matching solar panels, I was hoping as long as I could get the output really close to the same on a string I'd be ok. Perhaps that's harder than I thought, so maybe the microinverter set up is the way to go.
  • solar_davesolar_dave Solar Expert Posts: 2,379 ✭✭✭✭
    Re: Montana grid-tie PV installation: questions

    You can sort of work backwards to get a rough idea.
    20 kWh per day for 4 hours of good sun will equal a system producing 5 kWh per hour.

    Now divide that by 0.77 derating and you get a 6500 watt system.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Montana grid-tie PV installation: questions

    It's got to be said: look into every possible method of energy conservation first. The less power you use the better, with or without GT solar.
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Montana grid-tie PV installation: questions

    from the sound of things you are going to save to get this stuff so costs are your holdup. the microinverter system can get you up and running with some pvs now so you could start reaping the benefits while you save for some more that you can install next year after the weather breaks. winter production won't be huge, but if you tilt the pvs high enough (do get a variable angle mount with at least 2 angles to capitalize on the seasons) snow reflections can get more intense and the snow is less likely to stick to the pv. some go with a straight no adjust mount to save costs and are stuck with whatever angle their roof allows them to have. of course no matter the roof angle it must face south or close to it to get the maximum intensity of the sun. if you have the land you could also pole or ground mount the pvs taking the stress off of your roof. you could save with a diy setup, but remember that in a grid tied system that it will feed power to your main electrical box and the power available on the buses within it may necessitate a new electric service entrance panel. generally the bus can accommodate an extra 20% over the main breaker rating and this is what can be had on it with the solar unless you lower that total available power by using a smaller main breaker to the utility.
  • FrxddyFrxddy Solar Expert Posts: 113 ✭✭✭✭
    Re: Montana grid-tie PV installation: questions

    I guess I'm the guy that is going to suggest micro inverters. For me, and I would think a lot of people, they make it so Joe Average can install them. At no time are you working with high voltage DC. I understand 120-240 AC. I fear high DC voltage & do not have the knowledge to work with it. Micro inverters make each panel it's own individual system. Next week or next year when you want to add a panel or three, it will not matter if the panels match the ones you have now.

    I had two companies give me a price of $35,000 installed for a 7k system. I installed it myself for $25,600. (prices before tax credits, final cost about $18,000) I did end up foregoing the state rebate of $1,500 because I did the install.
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Montana grid-tie PV installation: questions
    Frxddy wrote: »
    I guess I'm the guy that is going to suggest micro inverters.

    really? vinn, who is the op, and myself both made mention of them.
  • FrxddyFrxddy Solar Expert Posts: 113 ✭✭✭✭
    Re: Montana grid-tie PV installation: questions
    niel wrote: »
    really? vinn, who is the op, and myself both made mention of them.

    Wow, I'm brain dead this morning. Please forgive? I did notice that Vin mentioned them, but I certainly blew it by not noticing your first sentence. My brain saw your good advice about variable angles, and the important advice about the main panel, but completely missed the word microinverter at the beginning.
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Montana grid-tie PV installation: questions
    Frxddy wrote: »
    Wow, I'm brain dead this morning. Please forgive? I did notice that Vin mentioned them, but I certainly blew it by not noticing your first sentence. My brain saw your good advice about variable angles, and the important advice about the main panel, but completely missed the word microinverter at the beginning.

    no problem as i get days like that myself.:roll:;)
  • meridiansolarmeridiansolar Solar Expert Posts: 34
    Re: Montana grid-tie PV installation: questions
    3. Anyone know any electricians in Montana on the list certified by NW Energy to install grid-tie inverters?

    http://www.nabcep.org/installer-locator

    is a good place to start.
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