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  • #16
    Originally posted by Sunking View Post
    Well like you say, Critical Thinking is one class de goberment is afraid of and not taught in public schools.
    Or, it seems to me, most anyway else as well. Lack of teaching that skill seems to me a big part of why/how we've wasted what the greatest generation and others behind them have left us.

    Now, back on topic for me anyway.

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    • #17
      Originally posted by john1970 View Post
      Hi,

      does anybody know if there exists a mechanism for fast switching between power from a domestic mains supply and the power from an inverter linked to my battery bank?

      The reason I ask is that I have installed small PV system but I think I am not using it to it's full potential. We have lots of sunny days where the system is always fully charged and we could run the household PC, lights, TV etc... then, when the sun sets, the battery bank voltage tends to drop off fairly quickly (batteries probably on their way out)... We usually manually switch over to mains power to preserve the power in the battery bank but at the moment this involves unplugging things, turning the PC off etc...

      I would love an automated switch that could change over from the inverter to mains power without interupption - does such a thing exist? If so what are they called? Or would it be easier to get a small UPS which could act as a buffer whilst we manually switch over?

      Thanks a lot,

      John

      Actually there is a device - solar immersion, that is mostly used to divert excess pv power to the grid. I believe you can use it for this purpose as I saw it in a pool for water heating. The device was configured to divert power from the inverter to the pool heater.

      Hi Neil - if you wish to advertise contact user name Jason please.
      Last edited by russ; 01-20-2015, 10:42 AM. Reason: removed link

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      • #18
        You can switch on the high side with something like this. You should have a common ground, so you can switch hot and the neutral with a cam switch...
        https://www.amazon.com/gp/product/B0...GLG0WJ17&psc=1

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        • #19
          O.P. 6 years old, better late then never? Merry Xmas

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          • #20
            We decided to go off grid with no grid connection because it was economical. The local power company wanted $140,00 just to get power 250m down the road! Our system cost $29,000 which runs a 4 brm house with no trade offs regarding energy use, so the decision was no brainer. I understand the fact using battery will often cost more that using grid power but I also think i depends on where you live. The average cost of power here runs at $1200-$1800 per quarter well over the $100/month you guys are lucky to have. In the end though you need to do your homework based on your local area as in some cases it is actually cheaper to move to battery over the long term as long as what you get is quality and your not fluffing around with crap products which don't work as promised.
            Just my thoughts, I'm new to this site so be nice

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            • #21
              That sounds like a reasonable economic trade off. Tell us more about your system. Panels, Inverter and batteries?
              9 kW solar, 42kWh LFP storage. EV owner since 2012

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              • #22
                Originally posted by donkey07 View Post
                We decided to go off grid with no grid connection because it was economical. The local power company wanted $140,00 just to get power 250m down the road! Our system cost $29,000 which runs a 4 brm house with no trade offs regarding energy use, so the decision was no brainer. I understand the fact using battery will often cost more that using grid power but I also think i depends on where you live. The average cost of power here runs at $1200-$1800 per quarter well over the $100/month you guys are lucky to have. In the end though you need to do your homework based on your local area as in some cases it is actually cheaper to move to battery over the long term as long as what you get is quality and your not fluffing around with crap products which don't work as promised.
                Just my thoughts, I'm new to this site so be nice
                Where is the site ? if in U.S : zip ?
                How much electricity (in kWh) do you use, or plan to use, over 12 months ?
                How big is your system, what is its orientation - tilt and azimuth ?
                How big and what type of storage do you intend to employ ?
                What type of backup generation are you planning on ?
                What does new have to do with nice ? You want reality or validation ?

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                • #23
                  System is 8.5kw tier 1 PV (32 panels) array with 2 sunnyboy inverters connecting to the house and the sunnyisland battery inverter with a 13.9 kwh BYD lithium ion battery as storage, The orientation is Solar North (southern hemisphere) with a 30 degree pitch/tilt. I have a 6kva generator as back up which i have used once.
                  I never said anything regarding new being necessarily nice! I said you need to make sure your not fluffing around with crap as there are plenty of sharks out there willing to take your money and provide dodgy equipment i.e tier 3 PV panels being sold as tier 1... New can be crap, and second hand can be very good you need just need to be careful. I don't intend on running anything I do run the system and have done for the past 18months with little or no issue. I use approximately 50% of my battery overnight if I'm running the dishwasher and have run the oven, if I don't run these things I use 30-40%.
                  As for reality and validation.......i'm not sure what you mean as i don't need validation and i live in the reality of a system which works.

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                  • #24
                    Originally posted by donkey07 View Post
                    System is 8.5kw tier 1 PV (32 panels) array with 2 sunnyboy inverters connecting to the house and the sunnyisland battery inverter with a 13.9 kwh BYD lithium ion battery as storage, The orientation is Solar North (southern hemisphere) with a 30 degree pitch/tilt. I have a 6kva generator as back up which i have used once.
                    I never said anything regarding new being necessarily nice! I said you need to make sure your not fluffing around with crap as there are plenty of sharks out there willing to take your money and provide dodgy equipment i.e tier 3 PV panels being sold as tier 1... New can be crap, and second hand can be very good you need just need to be careful. I don't intend on running anything I do run the system and have done for the past 18months with little or no issue. I use approximately 50% of my battery overnight if I'm running the dishwasher and have run the oven, if I don't run these things I use 30-40%.
                    As for reality and validation.......i'm not sure what you mean as i don't need validation and i live in the reality of a system which works.
                    Well I am glad you can get enough power from your system. Unfortunately most USA consumers use much more than 13.9kWh each day let alone only 50% of that each night.

                    I believe you have justified that living off grid system requires a very conservative power usage plan. I am glad you are ok with that.

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                    • #25
                      Originally posted by SunEagle View Post

                      Well I am glad you can get enough power from your system. Unfortunately most USA consumers use much more than 13.9kWh each day let alone only 50% of that each night.

                      I believe you have justified that living off grid system requires a very conservative power usage plan. I am glad you are ok with that.
                      Sorry, I should clarify that we use more than 13.9kwh per day (more like 18-20kwh over a 24 hour period. The 50% referred to overnight usage when the PV panels are not generating power. During the day the house runs off the PV panels and not the battery. The battery only kicks in when the load from the house is greater than what is being produced form the panels, Sorry for the confusion.

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                      • #26
                        Originally posted by donkey07 View Post
                        System is 8.5kw tier 1 PV (32 panels) array with 2 sunnyboy inverters connecting to the house and the sunnyisland battery inverter with a 13.9 kwh BYD lithium ion battery as storage, The orientation is Solar North (southern hemisphere) with a 30 degree pitch/tilt. I have a 6kva generator as back up which i have used once.
                        I never said anything regarding new being necessarily nice! I said you need to make sure your not fluffing around with crap as there are plenty of sharks out there willing to take your money and provide dodgy equipment i.e tier 3 PV panels being sold as tier 1... New can be crap, and second hand can be very good you need just need to be careful. I don't intend on running anything I do run the system and have done for the past 18months with little or no issue. I use approximately 50% of my battery overnight if I'm running the dishwasher and have run the oven, if I don't run these things I use 30-40%.
                        As for reality and validation.......i'm not sure what you mean as i don't need validation and i live in the reality of a system which works.
                        OK. Understood.

                        The reality/validation question was in response to your: "... I'm new to this site so be nice". Sometimes folks show up here and want to do little more than brag about some insipid stuff they've done, looking to get praise, and then get all pissed off when their folly is called out. To my experience only, the "please be gentle" stuff often come from such folks.

                        You're obviously a better informed person.

                        Was the cost to run power $14,000 or $140,000 ? That is, what was the "$140,00" as you wrote a typo ?

                        FWIW and not my concern, but if it's $14,000, depending on grid reliability, I'd probably spring for it. $140K changes the calculus.

                        Also, is the currency US$, or A$ or NZ$ or some other kind of dollar ?

                        Many/Most posters around here are, for better or worse, from the U.S. Telling us all where you are located up front helps us understand your situation or at least flags us ignorant U.S. posters that some of our assumptions about your conditions, including electricity prices and grid reliability may not be valid. For example, a $6,000 annual electric bill gets a bit more understandable if you're on some Micronesian island (that uses U.S. $) and power costs a buck/kWh and the cost of everything, including running power lines is through the roof because of relative isolation.

                        My question about annual usage was meant to go with my location question and what would have been a follow on question about grid electricity prices/kWh, and then a price/usage question that might provide some insight as to why the average annual (residential ?) power cost where you are runs ~ $6,000/yr, in whatever currency you're using.

                        One other thing: Not everyone in the U.S. has $100/month bills. While the ave. U.S. usage (11,000 kWh/yr.) and ave. U.S. price (.1331/kWh) works out to $122/month, I If I used the ~11,000 kWh/yr. as is about the ave. residential usage in the U.S, I'd be paying ~ $3.6K/yr, not $1.5K/yr.

                        But you are singing my tune when you write that users need to do their homework. Just too bad that most of them are ignorant of what's required to make informed decisions and apparently, at least how I see it, choose to remain so.

                        Welcome to the forum of few(er) illusions.
                        Last edited by J.P.M.; 12-25-2019, 09:09 PM. Reason: spelling

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                        • #27
                          Hi J.P.M,

                          Sorry for the confusion, I'm in The central western Ranges of NSW, Australia so A$ is the currency.

                          As for cost of running electricity it was a typo the cost quoted was $140 thousand dollars. Our grid electricity prices have risen sharply in the last 10 years so we on ave, are paying between 35-40cents per kwh plus a 85-95 cent daily supply charge. With 11,000kwh/yr its about $4700 inc, supply charge, so $366/month which all adds up. You can get discounts from suppliers which make a difference if you shop around but you usually need to bundle gas as well.
                          Hope that clears up a few things, Thanks for you reply

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                          • #28
                            Originally posted by donkey07 View Post
                            Hi J.P.M,

                            Sorry for the confusion, I'm in The central western Ranges of NSW, Australia so A$ is the currency.

                            As for cost of running electricity it was a typo the cost quoted was $140 thousand dollars. Our grid electricity prices have risen sharply in the last 10 years so we on ave, are paying between 35-40cents per kwh plus a 85-95 cent daily supply charge. With 11,000kwh/yr its about $4700 inc, supply charge, so $366/month which all adds up. You can get discounts from suppliers which make a difference if you shop around but you usually need to bundle gas as well.
                            Hope that clears up a few things, Thanks for you reply
                            Thank you for the reply and information.

                            If I was off grid because of high per kWh charges or high costs of getting grid power to a site, I'd only be using electricity for tasks such as lighting or communication or that that could not be done any other way by using nat. gas, propane or solar thermal. I still use a solar clothes dryer. Works great.

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                            • #29
                              Originally posted by donkey07 View Post

                              Sorry, I should clarify that we use more than 13.9kwh per day (more like 18-20kwh over a 24 hour period. The 50% referred to overnight usage when the PV panels are not generating power. During the day the house runs off the PV panels and not the battery. The battery only kicks in when the load from the house is greater than what is being produced form the panels, Sorry for the confusion.
                              Ok. I understand. I guess my question is what do you do on the days you don't get any sunshine for the pv system? Do you decide not to run any loads or do you use some other power source?

                              Unfortunately even here is sunny Florida we get a number of days each year when the sunshine is non existent due to bad weather.

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                              • #30
                                Originally posted by SunEagle View Post

                                Ok. I understand. I guess my question is what do you do on the days you don't get any sunshine for the pv system? Do you decide not to run any loads or do you use some other power source?

                                Unfortunately even here is sunny Florida we get a number of days each year when the sunshine is non existent due to bad weather.
                                Unless I'm screwing something up, it looks like donkey7 may live in a place that doesn't get many clouds. If he's near a place called Cobar, an 8.5 kW system will produce ~ 19kWh/day for all but 30 or so days/yr. and > ~ 14 kWh/day for all but maybe 15 of those 30 days. 3 day min. ave. totals are about the same. Looks like a place with a high clearness index (~ 0.63 or so) and not a lot of seasonal variability.

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