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Thread: adding a secondary solar system

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    Default adding a secondary solar system

    just wondering -
    I already have an existing 2.5kw system on my house which is pumping away quite happily ,but have been offered an old 1kw system for free . This is only 5 panels and an inverter rated at 1.5kw ( not sure cannot read the label ).

    would there be any unwanted side effects if i mount this second system to my shed roof and hook it up to the garage power circuit ? would it affect the existing system and / or the digital power meter?



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    I have had up to 5 arrays going at one time.
    As long as the output does not overload the power outlet ( obviously) there is no problem Normally.
    The only trouble you may have is high line voltage if The wiring to your shed is too distant or small and the other inverter is feeding the same circuit. Could not see that coming near a problem in this case if the shed is wired in 2.5MM but if it only has 1.5 wire which it shouldn't if there are power outlets it may go high on voltage and the inverter will trip it's high voltage protection.

    Other than that, you should be fine.

    There are many meters and depends how you are set up. Some meters record consumption and generation, some are seperate meters. In either case I can't see a problem given you already have solar. What is likely to happen is the 1 Kw system will supply your household loads and the present system will effectively increase it's feedback. If you are on a FIT you should see an increase in that if your consumption stays the same.

    You could also with the 1 KW system get some more used panels and put on it. You can over clock the inverters as much as you like. they will only do their rated output. Panels are far from 100% efficent so even 1.5 Kw of panels on a 1.5 KW inverter is rarely if ever going to make full capacity. By adding extra panels, you will get the inverter on song quicker and longer. With enough panels you could be at max output at say 9:30 am and stay there in summer till 6pm depending on orientation and tilt.

    The best part about over clocking the inverter with panels is you make good power when you need it the most, on shitty days and in winter.
    To also make the most of the off times, the flatter the panels the better. You only need about 5o tilt for cleaning . I have a couple of arrays at 7o and they work better than the larger tilted arrays in winter and i don't see the panels getting any more buildup on them. One of the arrays is south and because they are relatively flat they do very well in summer. yeah, they are crap in winter but so is my west array and generation falls through the floor even when everything is perfectly set up for winter. The energy just isn't there to start with.

    I was laughing to myself the other day that even though it was completely overcast all day long, I still made a lot more power than I often do on bright sunny winters days.

    You could look at getting some more panels if you have the room on the shed roof and hook them to this inverter as well. Don't worry about the wattage too much but do try to match the voltage close as you can and then parallel the arrays. You don't have to have the voltage spot on as the output pulls down and equalises itself out.
    I have one array that is 3 different sets of differing panels in output and voltage and they have been working fine for over a year now.

    If you are paying thousands for a new system then it probably pays to follow the " Rules" but I have found that like many things they are more fluff than hard and fast.
    All my panels and inverters are used and I have broken more rules than I have followed and never had any trouble and get good outputs from my systems.

    If you do intend to install a DC shutoff from the panels ( I don't bother half the time, Pull a connector apart quick or shut the AC off and then pull the connector ) be aware you can't wire an AC breaker through in the conventional way. DC will arc and burn the crap out of an AC switch in a couple of actions if it does not keep going till it sets the thing on fire. Probably not so much with teh size setup you will have but with one of my arrays Pumping 9KW....

    DC breakers are expensive so being a Tight arse I have used conventional 10A Breakers but used ganged pairs ( joined so they both switch together ) and wired both the pos and neg sides through the breakers. They arc no more than switching off a heavy AC load. Must have switched my big array 50 time now under load and no problem at all. Another thing I found is you CAN use normal DPDT relays on the DC switching. The trick I found and not to switch the DC off but rather to divert it. This gives the arc something to jump to that is a load and stops the arc. I found through testing that you don't need the dump load to be as much as the main load but 50% is about as low as I would go.
    I was switching a water heating element and was diverting to a stove element of much lower rating when I wanted to switch off the water heating element. Using the same relays with no dummy load on the other side gave big arcs twice then the relay melted and caught fire the 3rd time.

    This soundsl like a good score and something that you can save yourself and even make some bucks with possibly!

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    i have a twin setup here
    1 x 6.3 with a 5kw inverter installed new produces 42-49Kw on a good day
    on the main house

    1 x 1.5 with a 3Kw inverter second hand still producing 8 - 10kw on a good day
    on the guest house ( converted shed )

    i am looking at adding another 1.5Kw worth of panels to the smaller unit

    you just have to be sure of that the cable is capable of handling the
    power input to it and the distance as mentioned
    Last edited by fandtm666; 18-01-19 at 07:43 PM.

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    thanks guys , excellent food for thought.
    Ive still got a couple of questions if i may ? - I dont recall where i heard it but supposedly the council or Ergon Energy or someone take aerial photos of solar arrays , and can use that to ensure that people dont do exactly what i'm doing? I'm not too concerned about this though , if they bust me i'll just remove the second system.

    and secondly , on the main system ive just realised that i'm getting some shading from my TV antenna , so i'm looking at moving that somewhere else. I guess any shading at all , even from bird crap will significantly reduce output ?

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    You havent mentioned what state you are in ? I wouldn't be trying it in Victoria, but I presume you are not in Victoria because you can get a 5-6 kw system for about 2.5 kw after rebates.

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    I'm in QLD.
    after much consideration Ive decided not to to go ahead with any self - installed secondary systems in case something goes wrong , ( like a fire maybe ) and insurance companies become involved lol. in case i change my mind again Ive been to the local electrical supplier and all the roof tracks and parts are very easy and cheap to buy.

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    Quote Originally Posted by VroomVroom View Post
    I'm in QLD.
    after much consideration Ive decided not to to go ahead with any self - installed secondary systems in case something goes wrong , ( like a fire maybe ) and insurance companies become involved lol. in case i change my mind again Ive been to the local electrical supplier and all the roof tracks and parts are very easy and cheap to buy.

    pukpuk dont be chicken have a go at it just get someone to check it after you think you,ve done it right

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    I'm not a sparky but after the DOZENS of storys i have read on different sites where supposedly reputable installers have screwd up, ( not even mentioning the endless dodgy companies out there) the most worrying thing to me would be having someone else do a solar install.

    It's far from rocket science in difficulty and the alarmist warnings of fires are like all other gloom and doom warnings on the net, about 100K warnings for every actual problem that did occour. There have been more fires caused by Rooftop breakers by a hughe margin than anything else. Those breakers are a requirement for all installers to fit and even fire departments around the country have said they are dangerous and refused to have them fitted on their stations and premises citing the danger and the hundreds of cases where they have been the cause of fires.

    The stupidity of putting a breaker where someone has to climb onto a roof to shut it off in an emergency is moronic enough let alone the continual insistence of their fitment after hundreds of examples of them causing fires. I have isolators where they can be got to, on the ground and the protection I have is far greater than any qualified installer would allow.

    Working on ones home is also a very different thing to getting paid by the job with the prime motivation of getting it done fast as possible, collecting the money and getting onto the next job. Standards and rules are only minimums that can be done to ensure safety not the best solution. If I have to spend an hour more doing something or an extra $100 Bucks, so what? Doing the job beyond what is needed is always the cheapest in the long run and gives the best nights sleep.

    the do gooder whingers always crap on as if the worst case scenario is the only possible outcome. They inevitably have no skills of their own or balls and want to make themselves feel better by disparaging those not so useless. If one knows their limitations and looks up info or seeks advise before going ahead there is no problem.
    there are some things I can't or don't feel comfortable doing so I do what I can and ask or get help from a mate that can.
    When it comes to anything electrical, all sparky mate ever says is " What did you do it like that for? you didn't need to go to all that trouble and expense".
    When I hear that I know everything is OK.

    As it was before it got too hot I was out putting up more panels this morning. Been Umming and ahh ing about wether I need to or not but following the precarious state of the grid the last couple of weeks and coming to the inescapeable conclusion it's only going to get a LOT worse, I have decided I can't have too much backup.
    I'm setting up these panels so they can easily be changed from supplying a normal grid tie inverter to running a Charge controller for batteries I can run an inverter from.

    I have a Cheap PWM controller that I have used for a couple of years that I will get a few more of the same to give me the ability to run a 2KW inverter virtually direct from the panels with just a couple of small batteries as " ballast". Also looking to get a couple of 30 Kw heads this weekend to put on a couple of my diesel engines so I have generator power any time I want it.

    Doing solar is not at all difficult and one can learn from doing a system laying the panels on the ground and wiring it up and having it plug in to a power point. run that for a few weeks and play with it till you have set your mind at rest it's not going to catch fire.
    If one takes the stupid rooftop breakers out the equation, One would have to try very hard to cause a fire with solar if they wanted to. You would certainly have to go out your way to use something non standard and dodgy to make it happen that's for sure.

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    I am sure that the regulations state that there must be a DC isolation point at the panels and also at the inverter.
    In the electrical world, you want to isolate it at the supply and this is the panels.

    There was a dodgy batch of isolators that made the rounds and are the ones that are well known for causing the fires.

    Buy good quality components and install them to a high standard and you should not have a problem. But just remember you might be playing with open circuit voltages of 300+ volts DC.

    Sent from my SM-G960F using Tapatalk

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    thanks guys , ive read about the DC isolator being a requirement at the panels , and ive got no problem fitting one as the shop sells them along with a mounting bracket which goes under the panel.
    anyway i got the system for free and then loaned it to my neighbour , who has it sitting in his back yard purring away happily. He still has a rotary meter and we were laughing when it almost stopped ticking over !.

    I'll probably revisit the concept down the track a bit

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    Quote Originally Posted by VroomVroom View Post

    He still has a rotary meter and we were laughing when it almost stopped ticking over !.
    It is a good feeling that's for sure!

    My setups spin the meters back quite rapidly on a good day. Allows me to effectively use the grid as a battery. Except for winter, I have to turn the solar systems off before the next meter read in order not to have the power co come change the meters thinking they are faulty because I am in credit. I let them run up about 100Kwh each to keep them satisfied. One day they will come change the meters and my picnic will be over so I try to appreciate the benefits and savings I have now as much as possible.

    With the addition of the rest of the panels I have which will total about another 9 KW, I might be OK this winter. The falloff of generation is significant in winter and the fact I have limited north roof but a heap of west roof also means there is a loss of efficiency, again at it's worst in winter. That said, for what I picked these panels up for, they will have saved me more than they cost in one season.

    They are total and utter overkill in summer, I couldn't use the power I make now even deliberately trying to waste it. I'd love to find something useful to do with it but am at a loss. Growing weed would be a productive outcome but being clueless as I am with the way that works, the first person I'd probably try to sell it too would be an undercover cop that the more educated types would spot a mile off and be pissing themselves laughing as I was cuffed and taken away.

    Couple of months back just after the last read, I spent days Boiling hundreds of liters of water. Boiling water makes a great weed killer that does not contaminate the soil and you can replant 2 hours after treatment.

    People often look at me as if I'm crazy with the amount of solar capacity I have but if I rated it in the terms of what I make per day in winter, it would sound far more modest. It's not the maximum one needs to worry about, it's the minimum winter generation. Optomise for that and the summer yields will take care of themselves.

    I will have a play with the panels I just put up tomorrow. Using the areas of the roof over the sunroom as it were given good positioning of the panels but because the areas are small and the panels have different orientations, it looks like crap from the ground. Not supposed to have the panels on different planes on the one string but again that is more pedantic crap far as I'm concerned.
    I might put a couple on the flatter areas of the roof and use some brackets for holding the rails to the roof bearers directly on the panels to give them a little northerly tilt at least and see how that looks.

    I came across this page today that was all about bad solar installs. Only re affirmed my distrust of installers. Sure, My systems violate just about every regulation going but I could never be convinced they are in the least bit unsafe. What I saw today on this page that was done by the so called professional installers made me cringe. The shortcuts and stupidity so many things typified was quite unbelievable.
    There were LOADS of pics of burnt rooftop isolators which would put me off having them even if I wasn't put off having them already.

    Seems none of them are really up to enduring the weather when exposed to the full force of the elements for near the life of other components no matter what brand they are. There are few places in the world that have this reg which says something in itself.

    The nice part of doing ones own system is the mere fact one is DIYing it makes it non compliant from the outset. From then on, you don't need to worry about rules and regs, you can concentrate on making it as safe and reliable as possible instead. :0)

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