First post and question...

[spud143]

Hey just getting started in solar and have some stupid questions for you guys ... in a grid tie system do all panels have to be the same ? Volts , watts ..

[Mike90250]

That depends. If you are using a string inverter, the panels need to be matched in Amps, and the total string voltage within the inverters operation window.

If you use micro inverters, you install one inverter on to a properly sized panel, and you can have as wild of a match as the micros will accept,

[spud143]

Don' have the inverter yet which way would you recommend? And which would be the least expensive of the two ?

[jflorey2]

Don' have the inverter yet which way would you recommend? And which would be the least expensive of the two ?

There's also a third way which is sort of a hybrid of the two which is the Solaredge. (DC optimizers on the panels, and a central DC to AC converter.)

If you don't have any issues with shadowing and you are doing it all at once, string inverters are a bit cheaper and easier. (No electronics other than the panels on the roof.) If you do have shadowing or other oddball issues (i.e. mixed panels that can't be handled by a string inverter, many different orientations) then the micro or Solaredge solutions make more sense.

[spud143]

Thanks for your help I really appreciate it .. I don' have any shadowing issues but I'm not able to get everything at once so there may be some miss matched panels...

[Sunking]

FWIW if you live in the USA, you will most likely be required to pull a permit and pass inspection by the local AHJ and the POCO. Mixed panels will not fly and I doubt you would have the skills and education necessary to pass an inspection. Electrical codes and workmanship take several years of experience to master.

[spud143]

I'm in Canada...

[J.P.M.]

I'm in Canada...

Most of the plumbing, electrical and building codes are similar but not necessarily identical one country to the next. My limited experience in dealing with Canada's codes is that they often make a bit more sense, but can often be maybe a bit more stringent up front in spec. requirements and maybe a bit more trusting when it comes to code conformance and inspections.

In either country, it's always best to follow safety and good design practices if for no other reason than penalties associated with non conformance if/when you get caught.

Knowing what is involved in code conformance is also a good way to begin learning the basics of what helps make a design safe(r), and also learning some of the fundamentals of good design, PV and otherwise.

Before that, stop what you're doing and invest a few C$ and read "Solar Power Your Home for Dummies" for a primer in the basics of residential PV. You'll learn a lot more and learn it a lot faster than by fishing expeditions on web sites. Learn from the bottom up.

Welcome to the neighborhood and the forum of few(er) illusions.

[spud143]

Any good recommendation for sites to buy equipment also does this site have a used equipment or marketplace type section ..

[jflorey2]

Thanks for your help I really appreciate it .. I don' have any shadowing issues but I'm not able to get everything at once so there may be some miss matched panels...

If you are going to piecemeal it a lot (i.e. spread it out over years) then microinverters might be the better way to go. That way you can take advantage of improvements in inverters _and_ panels. The risk will be that the communications system (i.e. the Enphase Envoy system for example) will get replaced, so you'd have one set of inverters using the old comm system and one set using the new one.

[spud143]

Yes that's kind of what I need to do .. but I'm having a hard time finding anyone that has gone on a net metering program with a diy system ..

[Shubunkin]

Hi - Just joined and I have a question. Perhaps I just didn't know how to search the forums properly. We are building a house in NC and want to use solar, but the local co-op has severe disincentives for connecting to the grid (in addition to adding monthly fees, they will buy at wholesale and sell back to us at retail.) We would like to have a system where we could use our own solar but have back-up from the co-op. I thought about batteries but have heard they are not cost/ecologically efficient. Is there any way to have the house use solar as the priority, and only draw from the co-op when necessary (no feedback to co-op so no fees?) I know we can just minimize the solar to a small portion of our usage along with continual draw from the co-op, but that seems kind of contrary to the point of having solar in the first place.

[Mike90250]

Hi - Just joined and I have a question. Perhaps I just didn't know how to search the forums properly. We are building a house in NC and want to use solar, but the local co-op has severe disincentives for connecting to the grid (in addition to adding monthly fees, they will buy at wholesale and sell back to us at retail.) We would like to have a system where we could use our own solar but have back-up from the co-op. I thought about batteries but have heard they are not cost/ecologically efficient. Is there any way to have the house use solar as the priority, and only draw from the co-op when necessary (no feedback to co-op so no fees?) I know we can just minimize the solar to a small portion of our usage along with continual draw from the co-op, but that seems kind of contrary to the point of having solar in the first place.

That would be Grid support mode, but as your load in your house varys during the day, you will have surplus that you do not sell. You will still have to enter an agreement to connect your inverter to their grid.

[Shubunkin]

Is there any way to connect batteries to store the surplus and not have it go to the grid? I'm not sure why we need to connect the inverter to their grid; can't it be a parallel system?

[jflorey2]

Hi - Just joined and I have a question. Perhaps I just didn't know how to search the forums properly. We are building a house in NC and want to use solar, but the local co-op has severe disincentives for connecting to the grid (in addition to adding monthly fees, they will buy at wholesale and sell back to us at retail.) We would like to have a system where we could use our own solar but have back-up from the co-op.

Well, as Mike mentioned, you can do grid support (or grid zero) which will prevent any selling of power back. However, this is still worse than normal grid tie, since you are choosing between getting almost nothing for your "surplus solar" and getting nothing for your "surplus solar."

I thought about batteries but have heard they are not cost/ecologically efficient.

Correct. There are very few cases where batteries make financial sense.

Is there any way to have the house use solar as the priority, and only draw from the co-op when necessary (no feedback to co-op so no fees?)

That's how regular grid tie works. It uses one meter for all generation and usage.

Solar generation of 4kW, usage of 2kW - 2kW flows to co-op (and you get peanuts.)
Solar generation of 4kW, usage of 4kW - zero power flows anywhere. As far as the co-op is concerned you are using zero power.
Solar generation of 4kW, usage of 6kW - You purchase 2kW of power from the co-op.

The one way they could hose you is to require two meters. If they do that, they might give you only 1 cent credit per kwhr and still charge you 15 cents per kwhr. (In other words, you aren't even getting credit for reducing your draw from the utility.) In that case you are usually better off with a grid zero system that does not export (if they allow that.) It would depend on the relative credit/cost for power.