Announcement

Collapse
No announcement yet.

What if I need to expand?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • What if I need to expand?

    We are looking at going full solar for the house. Our grid bills show us at about 700kwh per month but there is an electric stove and electric water heater in that mix. We would go with Propane for those so I guess we can drop about 40% off 700-that number.

    I'd like to get an idea of what is a reasonable system since money is tight and we are prepared to lighten up on our misuse of the solar-power. By misuse I mean leaving stuff running that should be turned off, like lights etc. It is easy to be cavalier when there is an infinite supply.

    I do not yet know and understand all that is required for a minimal system, but expansion is an issue I need ti understand first. If we were to put in something that will satisfy say 10kwh per day and it is too hard to live within that, how do we add in more?

    Can I parallel up the outlets of the inverters (from same manufacturer) or would we have to run separate 110v outputs to groups of circuits in the house?

    As in, the initial system runs 110v to the top 6 breakers in the house, a second add-in system runs 110v to the next 6 breakers.

  • #2
    That's why your current load assessment and future projections are SO important. Convert to gas heating & cooking now. See what you can reduce bills to NOW, and you will have a better baseline to project from.

    I'm somewhat troubled by your statement:
    > .... the initial system runs 110v to the top 6 breakers in the house, a second add-in system runs 110v to the next 6 breakers.

    this reads to me, that you have installed (or are thinking of) many small Plug-In inverters. Plug in inverters are not currently legal, nor is there any path to being certified for use in USA because of a large potential for fires in the household wiring. Legal grid tie inverters are nearly always 240V, which reduces the amps and fire risks, and are well tested and certified, and often run 96-99% efficient. Mini-plug in inverters vary widely in their actual efficiency from 70-90% so you are throwing away hard fought for solar with them, and risking electrical service disconnection for illegal connection, since no utility will allow a connection with plug in inverters.
    Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister

    Comment


    • #3
      Do as Mike writes. Know your loads and minimize them as your lifestyle permits before you get any solar equipment. Prior to that and as a go by, or concurrently with your load analysis/reduction, get a copy of "Solar Power Your Home for Dummies". A slightly outdated version is a free on line download. A newer/revised copy is ~ $20-25 at bookstores/Amazon.

      Knowledge is power. You need more education. Get more of both before you talk to vendors/buy anything. You'll wind up with a better system (if you do indeed choose to get some PV after the education) that's more properly sized, more fit for purpose and for probably less $$.

      Upgrade your electrical system as safety/needs dictate but don't change it around for the sake of PV.

      Replacing appliances that use electricity as a fuel source (and a low entropy - meaning high quality - energy source) when the task can be done as well or better/cheaper/faster by fossil fuel /solar thermal means (a high entropy source) is usually a good way to reduce electric bills and FWIW, in the long run usually better for the environment.

      FWIW, in general, it's usually better to use electricity for tasks that can't be done using "dumber" energy sources. Example: It's hard to run the screen you're looking at on propane, but when electricity is used as a heat source, particularly electric resistance heat, the fuel cost can easily double/triple over the cost of the fossil fuel required to do the same task.

      However, the initial cost/changeout to fossil fuel source equipment needs careful analysis and balance against the potential savings from all the alternatives.

      One example/question: Is it worth changing out a currently fit for purpose and functional electric tank type water heater to a propane fired unit for, say, $1,000 to save, say, $200/yr. in differential fuel cost ? $100/yr. ? What if you first reduced the hot water load by 50% through conservation/improved insulation/less water waste that reduced the savings from the changeout to $100/yr. while waiting until the current electric tank failed ? Lots of options.

      Get the book. Come back and ask questions about any knowledge gaps your self education creates.

      Welcome to the neighborhood.

      Comment


      • #4
        Originally posted by KaneDaly View Post
        We are looking at going full solar for the house. Our grid bills show us at about 700kwh per month but there is an electric stove and electric water heater in that mix. We would go with Propane for those so I guess we can drop about 40% off 700-that number.

        I'd like to get an idea of what is a reasonable system since money is tight and we are prepared to lighten up on our misuse of the solar-power. By misuse I mean leaving stuff running that should be turned off, like lights etc. It is easy to be cavalier when there is an infinite supply.

        I do not yet know and understand all that is required for a minimal system, but expansion is an issue I need ti understand first. If we were to put in something that will satisfy say 10kwh per day and it is too hard to live within that, how do we add in more?

        Can I parallel up the outlets of the inverters (from same manufacturer) or would we have to run separate 110v outputs to groups of circuits in the house?

        As in, the initial system runs 110v to the top 6 breakers in the house, a second add-in system runs 110v to the next 6 breakers.
        Most approved inverters output 240VAC, so they cannot on their own operate 120V
        circuits. In addition they are designed to shut down when the grid is not present.
        Besides safety to line workers, there is another need. An MPPT inverter makes high
        efficiency use of the highly variable renewable energy, to get whatever power the
        panels can deliver at each moment. That much varying energy must be sent
        somewhere, but will almost never be a match to what your loads need at the moment.
        A solution to that problem, is to temporarily send it out to that infinite energy sink
        of a net metering grid tie.

        A second solution is to stay with DC and dump the power into a battery of sufficient
        capacity. This is a critical function, as batteries are easily damaged.

        I did manage to get down to 10KHW a day in warm seasons here. That took a lot
        of effort to minimize waste, not just a couple things, but for every item on 60 circuits.
        Vampire loads, stuff using power even when off, can kill your efforts. Energy star
        stuff is your friend. The furnace in winter drove my annual use to 5000KWH. Get
        measurements on everything, and the picture will become clearer.

        If money is tight, it is far more economical initially and far less troublesome later
        to use a net metering grid tie instead of batteries.
        good luck, Bruce Roe

        Comment


        • #5
          Tell us what part of the country you live in and whether your power company offers net metering? I understand you expect rates to approach $0.30 per kWh. Is that a flat rate or does your power compny offer Time of Use rates? Do you have the inclination or the resources to self install or do you need a turn key system? There are several paths to accomplish the goals you outlined earlier. A lot depends on how you can leverage opportunities in your marketplace to optimize your financial investment.

          9 kW solar, 42kWh LFP storage. EV owner since 2012

          Comment


          • #6
            I have three arrays each with grid tied inverters. They were installed over the course of 18 years and somewhere along the way I upgraded one of the arrays with different panels so I have had four different arrays at one time or another.. The price per installed watt keeps coming down although the federal solar rebate is already sunsetting. It was 30% in 2019, 26% in 2020 and 22% in 2021 and then 0% after that unless its extended. The biggest issue with adding systems on is the aesthetics of how they look. Panels types and physical sizes have changed, every solar panel not bought at the same time from the same manufacturer will probably look different and the trend is for panels to keep getting physically larger. This means that future expansions will look different and will most likely not look very good butted up against an existing array. If the panels end up an adjacent roof section with valley in between its most likely far less of an issue.

            All three inverters "play well" with the utility. I had an issue at one point with an undersized cable which was my fault that would trip one of the arrays but it got fixed quickly with some bigger wire.

            Technology has not stood still and building codes definitely have not. One array is too small to even buy a replacement inverter, the next is on my roof and its not equipped for rapid shutdown that is now required. In order to expand the roof array I would need to install microinverters or optimizers on the existing panels to replace my string inverter before I could expand it. My third array is a pole mount and as far as I know its code compliant to the current code. Of course no such thing as a free lunch as a pole mount normally costs a bit more to install. I do my own labor so the money I save in labor pays for the extra material cost I might spend. I like DIY and have installed all these arrays by myself with no help, including rigging panels up in the air and on my roof. Its part of the fun figuring out a safe way to do this solo

            Microinverters or panel mounted optimizers seem to "own" the market these days due to the rapid shutdown requirements and I expect that may be the case for a few years. Panels are relatively cheap these days so one concept is just buy spare panels and store them until you need or want to add them. Sure you may have to mess with a different racking system but if you stick with a known brand they seem to somewhat backward compatible.

            Whatever you do, do the research first, make sure you understand what is legal, take a good look at your future demand and then and only then consider buying any parts. Folks pop up all time on this and other sites where they "got a good deal" and we get to explain to them that their "good deal" is close to worthless.

            BTW under my utilities' rules which can vary substantially by state and utility, I can generate extra power and bank it for as long as the house stands. I intentionally generate extra power and run a mini split heating and cooling unit to burn up some of the extra. I am basically "bottling sunshine" in the summer and using it on cold day in the winter.as I live in a cold area.

            Comment

            Working...
            X