Combiner boxes On array or by Meter?

toppertopper Solar Expert Posts: 113 ✭✭
CEC inspector I talked to said he didn't care.
I am looking at 3 2378 watt arrays. What would you do?
Install them on each array or bring them down to an accessable location beside the power meter.

Comments

  • BB.BB. Super Moderators, Administrators Posts: 32,006 admin
    Re: Combiner boxes On array or by Meter?

    I would probably have a slight preference for the breakers near the solar array--That would allow you to kill the DC power for the run back to the GT inverter if you ever need to work on that run (trenching, squirrels ate through insulation, etc.).

    Otherwise, I would just look at cost of combiner boxes (several small ones, one large one), cabling, and where is it the easiest to make all of the electrical connections--i.e., at the arrays or at the GT inverter (working with large gauge copper cables can be their own source of fun too).

    Do the "paper design" first and figure out the wire gauges, breaker sizes, etc. first and see what ends up being the easiest/cleanest to install.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • dwhdwh Solar Expert Posts: 1,341 ✭✭✭
    Re: Combiner boxes On array or by Meter?

    My $0.02...

    From a troubleshooting point of view, it's nice to have a disconnect up by the unit (solar, HVAC, whatever). It's a real pain if you have to keep humping up and down the ladder when trying to suss out why one of the breakers is tripping.
  • stevendstevend Solar Expert Posts: 34
    Re: Combiner boxes On array or by Meter?

    I thought there was something in the Canadian Electrical Code about the disconnect means having to be in an easily accessible location (i.e. not on a roof, not need a ladder to access, not up on a pole) but I can't find it now so it must just have been a recommendation. But you can still have a combiner box in an inaccesible location and still have a separate disconnect elsewhere.

    Also, the wires you have available might be a consideration. Since you have 3 arrays you either can run 3 long sets of thinner wire from the array to a combiner box near the meter where you'll have a short thicker wire or you can combine near the array and run 1 long set of thicker wire down to near the meter.
    -Steve
  • toppertopper Solar Expert Posts: 113 ✭✭
    Re: Combiner boxes On array or by Meter?

    I do agree with both sides. Combiners on the arrays would ease troubleshooting. I overlooked that aspect. That would leave me with less on the side of the house. One triple leg disconnect for the PV in an easily accessable location right beside the meter(s).

    Next Question concerning CEC and more specifically, Saskpower Net Metering.

    According to Saskpower net metering, if I wish to get a 35% rebate I need total production metering.. I plan on running an XW inverter with a battery backup.
    With the XW system, I would require :
    1 net meter saskpower (main grid in) .
    1 net meter between the main service panel and inverter (import/sell to grid)
    1 net meter between the inverter and my backup loads panel.
    Am I having a brain fart here ? 3 meters?

    I quizzed up an inspector but he was unfamilliar with this kind of setup.

    Anyone with info I would greatly appreciate it.
    Thank you
  • BB.BB. Super Moderators, Administrators Posts: 32,006 admin
    Re: Combiner boxes On array or by Meter?

    Some of the guys up there in Canada are getting nearly $0.85 per kWH for solar power... With the XW inverter--there is no good way of installing a production power meter to measure just Solar production...

    So, it sounds like they are trying to do you a favor... Two meter on the XW system to use the difference to find the "true solar power output". And a third meter for the power into the home...

    I would have to think about it how well it will work (AC mains, GT power, battery backed power, generator backed power, AC mains charging battery bank, Generator Charging battery bank, etc.) and how all they plays into the billing... You might end up "paying" for battery backed/Generator Backed power (possibly even the $0.85 per kWH rate to generate/use your own power)... Hmmmm.

    It sounds like it would be a heck of a lot easier to put in a plain GT inverter.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Ralph DayRalph Day Solar Expert Posts: 952 ✭✭✭✭
    Re: Combiner boxes On array or by Meter?

    In Ontario the microFIT program pays 80.2 cents per kwhr. There is no provision for batteries in a microFIT project, only straight sale to the utility (grid tie only inverters).

    Ralph
  • stevendstevend Solar Expert Posts: 34
    Re: Combiner boxes On array or by Meter?

    topper,
    Unfortunately the meter requirements differ even more than by province but maybe this info will help you track it down. Here in Ontario it's up to what we call the Local Distribution Company (LDC). They're responsible for managing their area's transmission lines, poles, transformers, right down to the breaker panel in your house. We have around 80 different LDCs. From my web research it looks like in Saskatchewan you refer to them as electric utilities and yours is SaskPower (?), though it looks like your utilities are allowed to do more than ours. By Ontario provincial law, all LDCs must support net metering. Almost no one does net metering and do our microFIT program instead but if I recall correctly, Hydro Ottawa (Ottawa's LDC) requires two meters, one for each direction. That was supposed to change to just one once our smart meters came in.

    As for the CEC, there is one and most provinces just use it. However, some provinces just use it as the basis for their own electrical code. We do here in Ontario and so we have the Ontario Electrical Code. But as I said, in Ontario it's up to the LDCs to say how the metering is done.

    You might want to look at the following two links. In my experience, metering details on utility and government websites are often generic simplifications so keep that in mind. The first is SaskPower's net metering page (provided I have the right SaskPower). On that page they mention "a bi-directional meter that is installed by SaskPower". They also mention some funding you can get for net metering from the Saskatchewan Research Council (SRC). The second link is about the funding.
    http://www.saskpower.com/sustainable_growth/generate_move_power/net_metering.shtml

    http://www.src.sk.ca/html/research_technology/energy_conservation/net_metering/index.cfm

    -Steve
    PS. To clarify, Ontario's two Feed-in Tariff programs, microFIT (<=10kW) and FIT (>10kW) programs, are seperate programs from net metering. If anyone's curious, I have summaries of Ontario's net metering and Feed-in Tariff programs here:
    http://rimstar.org/renewnrg/sptypes.htm
  • stevendstevend Solar Expert Posts: 34
    Re: Combiner boxes On array or by Meter?

    topper,
    Just thinking some more about it... Since 3 meters seems a little much, maybe SaskPower is at the stage that Hydro Ottawa was when I first contacted them. I was the first person ever to contact them regarding net metering. By law they had to implement it but it was new and they were still working it all out. Basically you have a group of engineers tasked with figuring out a way to make it work with their system that is safe, reliable and accurate. It isn't easy or obvious. And usually they're glad to talk to someone else who's already done it. I know Hydro Ottawa was open to that at the time. If you'd like me to, next week I can try and track down a contact for them at Hydro Ottawa. Or you can just suggest that they contact Hydro Ottawa themselves and have their respective engineers talk.
    -Steve
  • toppertopper Solar Expert Posts: 113 ✭✭
    Re: Combiner boxes On array or by Meter?

    I do beleive I missread the saskpower requirements.
    Now that I reread the terms, it does make a whole lot more sense. Just 1 net meter reading the grid connection. Well now that simplifies things a lot..
    Long story short, if the gov't is handing out 35% of my costs I want to take full advantage. Thanks Steve and it does appear that I did experienced a BRAIN FART.
    BB I was thinking a couple days ago that a GT may end up being easier. Down side to that is our unreliable power grid in the area. I truly feel that a backup system is warranted here. I know a genset would suffice but after 3-4 days of no grid, genset is out of fuel and it gets mighty chilly up here in the winter.
    So my dreams of running an XW, solar, with backup battery bank and genset are still in the green.

    Thanks to all and let the sun shine in.
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