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Thread: generator inverter or solar

  1. #1
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    generator inverter or solar

    Trying to figue out a cost effective method of powering my house...not only for load shedding...but a way to have a pure sine wave feeding my electronics at home.



    No return on investment installing a generator...starts costing as you install it...what seems common...people dont maintain the generator so the day you need it...carb is blocked or diesel requires bleeding...so it is off to the generator service guy and you end up with another bill.

    ...plus the fuel costs and services....etc etc...for those 12 hours blackouts...and the fridge needs to run etc...a generator is a good way to get all those heavier loads up and running...not forgetting the terrible distorted sine wave it produces.



    So then we look at an inverter connected to the mains charging batteries ...pure sine wave...an investment? ...i would think so...not only are you providing a pure sine wave...if installed correctly...could also save your electronic devices/hadrd drives etc from minor over voltages or dips...much like installing an online pure sine wave UPS back in the old days...connected via batteries...thats where it starts getting expensive and replacing the batteries ever 5 -7 years becomes a huge capital out lay.



    Now we look at a solar setup...add an charger unit/inverter and a pile of batteries and you in for around R60 000...for a 6 kva unit....my response would be too expensive...and not an option for a home..



    So i have been thinking cut out a pile of batteries and your 5-7 years huge capital outlays is no longer a nightmare from hell...but then why waste the money installing only solar panels if you are not home during the day and your max demand is in the evening from around 5 pm...by that time the sun is already going down...now that i am looking into finding a solution for my own house...it got me thinking.



    Here are my thoughts for my house.



    An affordable outlay...sell one of my bicycles (R20k ) and invest the money into my house...buy a start kit ...by this i mean 1 or 2 solar panels to get me started...a solar charger/pure sine wave inverter (24 volt)...and just 2 batteries (12 volt 100 amp/hr) ...



    the system will run all the electronics in the house with the the battery as a backup...the alarm...which will be linked to the phone app so that i can control everything from my phone...open and close gates etc...cctv system also connected to an app for remote viewing...to check the gate which will also be controlled by the phone...control LED lights around the house...ADSL router and the TV...so no matter if there is load shedding or not...all this stuff will have power.



    The solar panel will feed power into the house during the day and charge the batteries...depending on the size and quantity of the panels the more stuff will run...fridge...pool pump etc and as more panels are added so feed more items...to a point that hopefully it will start turning my meter backwards ( i told i am not allowed to do this)...there was talk at one stage about getting a refund...i cant see that happening...i believe we will be taxed before we are credited.



    These are just my thoughts...please share your thoughts or ideas...i might be way off the mark.

  2. #2
    Diamond Member Justloadit's Avatar
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    If you look at Lead acid batteries, then you have to consider that it requires q 24 hour charge cycle.
    Also discharging a lead acid regularly by 70% of its capacity will reduce the cycles dramatically to maybe 30 or 40 if you have a deep cycle battery.
    Discharging to 50% of capacity will give approximately 200 cycles before your battery capacity slowly starts getting lees and less.
    Discharging only 30% capacity of your battery will give you approximately 700 cycles before capacity starts to be affected, and will require the current from the battery capacity in the charger, so the PV side has to be larger and off course more costly.

    The best solution is lithium, which can charge in 4 hours, and can be discharged to 20% of its capacity regularly and will give you approximately 1000 cycles, discharging less on each cycle will increase the number of cycle times.

    Do the maths - lithium is more expensive from the onset, but cheaper over the long run.
    If you intend to do higher energy from your system, then start with a higher voltage inverter rather than smaller. The battery current is going to catch you with wire size and losses.
    Some quick numbers to show
    1000watt load
    12V = 83Amps
    24V = 42Amps
    36V = 28Amps
    48V = 21Amps
    Do a price check on cable size, now double up the inverter size, and note the amps and cable required.

    NOTE! Use only DC rated switch gear and circuit breakers for all protection and isolation.
    If you don't believe me do a google surge on dc and circuit breaker fires, you will get a shock of the dangers when disconnecting the load.
    Some DC breakers are polarity orientated, and make sure when using them that you follow the source input to the breakers as incorrect connection will cause fires on switch off or trip under load.
    Victor - Knowledge is a blessing or a curse, your current circumstances make you decide!
    Solar and LED lighting solutions - www.microsolve.co.za

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    Quote Originally Posted by Justloadit View Post
    If you look at Lead acid batteries, then you have to consider that it requires q 24 hour charge cycle.
    Also discharging a lead acid regularly by 70% of its capacity will reduce the cycles dramatically to maybe 30 or 40 if you have a deep cycle battery.
    Discharging to 50% of capacity will give approximately 200 cycles before your battery capacity slowly starts getting lees and less.
    Discharging only 30% capacity of your battery will give you approximately 700 cycles before capacity starts to be affected, and will require the current from the battery capacity in the charger, so the PV side has to be larger and off course more costly.

    The best solution is lithium, which can charge in 4 hours, and can be discharged to 20% of its capacity regularly and will give you approximately 1000 cycles, discharging less on each cycle will increase the number of cycle times.

    Do the maths - lithium is more expensive from the onset, but cheaper over the long run.
    If you intend to do higher energy from your system, then start with a higher voltage inverter rather than smaller. The battery current is going to catch you with wire size and losses.
    Some quick numbers to show
    1000watt load
    12V = 83Amps
    24V = 42Amps
    36V = 28Amps
    48V = 21Amps
    Do a price check on cable size, now double up the inverter size, and note the amps and cable required.

    NOTE! Use only DC rated switch gear and circuit breakers for all protection and isolation.
    If you don't believe me do a google surge on dc and circuit breaker fires, you will get a shock of the dangers when disconnecting the load.
    Some DC breakers are polarity orientated, and make sure when using them that you follow the source input to the breakers as incorrect connection will cause fires on switch off or trip under load.
    The catch is battery replacement costs...the more voltage the more batteries required...however i agree with you higher voltage is a better option.

    I take it you are talking about the lithium 18650 ...3.7 volt batteries.

    I cant understand why nobody is offering a basic expandable solar kits which are affordable to joe soap with the option to expand over time.

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    Something i learnt last night while speaking to a man a a solar project...you get grid tie inverters which you can install and connect to the incoming mains directly...then you can add more of them and they sync with each other and the supply voltage.

    4 panels and a grid tie inverter with 2 x 12 volt batteries...to make up a 24 volt system (or i am liking the sound of lithium ...certainly the way to go)

    I need to get smart with regards to this technology and add a little smart tech remote cctv viewing...remote alarm control...open and closing gates etc and quickly...i believe there is a massive market for simple solar ...inverter and even a battery or 2 depending on the customers budget...offer small credit facility and i would be able to close my electrical business and retire.

    People mention solar and suddenly there is a R60 k budget required ...make and affordable expandable system for around R10-15 k with a credit option 2 or years and you will be making some good money.

    generators are not the way going forward ...

    i cant see wind power taking off...

    inverter with lead acid batteries is also not the way to go.

    solar...charger/grid tie inverter and lithium batteries is going to be the future....thats were i would go.

    To add...with all the electronics in the house and bad electricity supply...a pure sine wave inverter would not only be offering you a charger...money saving electricity solution ...but also protecting your electronics from dips and surges...i do realise most people have insurance to cover and like the idea of replacing the TV etc every couple year safter a surge... but if the insurance companies got smart this would be the way to go.

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    Bingo a little scratching and i have managed to source a company which already supplies lithium batteries in stead of lead acid batteries with their solar panels and inverters

  7. #6
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    Time to scratch up this old thread:

    A year later a lot wiser.

    What have i dont since then ... I have a 5.5 kva generator ...ideal for home or site ... i know i mentioned it was a bad idea ...costs involved and all ... but i now have one ... it can run all the big loads like the fridge etc ... mine serves 2 purposes ... one for those long 12 hour power outages and secondly for site work so it is not a totl waste.

    I have since tried other things like using a UPS and a inverter (modified sine wave) to run backup lights ...was a bad idea ... the LED lights just flicker ... so i invested in a 5 amp charger with an 18 amphr battery ... a 5 metere strip of LED lights ... took some old linear light fittings which no longer work ... removed the old 230 volt strips and controls ...fitted the 12 VDC strip light ...drilled a hole into the roof ...fitted a DC plug and bingo load shedding lighting sorted.

    The bonus about the linear LED light fittings ... they have a clip which mounts on the ceiling and the fittings clips into place ... so if I want to replace or upgrad ethe fitting ... i just unclip the light from the ceiling ... pull some slack out hte roof unplug the DC plug and replace the fitting.

    The lights are controlled using an exo 7 receiver (12VDC) and a 6 relays ... with a 4 button remote and because it is all 12 VDC ... there are no losses converting from DC to AC and back to DC ... the lights can also be switched on/off using the touch keypad for the alarm ... or the alarm app.

    The next step is to add a small solar panel to charge the battery ...and eventually i will upgrade the battery to a lithium battery ...but for now capitial outlay is limiting progress ... so it is more about getting it to work ... then improve as we can afford it or replace if i find a bette rsolution.

    The next step is the solar install ... looking into grid tie and hybrid ... they both serve a purpose and there is a good chance i will be installing both ... but it is going to be done in phases as the budget allows.

    I need to figue out a way to fit panels like 2 or 4 to get started ... then a grid tied inverter to start reducing my electricity account ... the plan is to power the garage/ workshop and the stove during the day ... both used to genarate income ... garage building product to sell and the stove ... the baking bussiness ... both consume a fair amount of power during the day ... as the bussnisses generate income so the money can be used to exapnd the system until we become self sufficient.
    Comments are based on opinion...not always facts....that's why people use an alias.

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    Hi Ians

    Nice topic.

    We have downscaled as far as our accomodation is concerned. Small, low maintenance 2 bedroomed house with 1 bathroom, open plan lounge, dining room and kitchen and a single garage.

    Inside DC lighting consists of 5 of 12V 4W downlights placed in strategic spots.
    Outside DC lighting consists of a 12V 10W spotlight out front and the same out back. Total 40W.

    Supply is from the garage via 2 crocodile clamps.

    When needed, just pop the bonnet and connect to the car battery with crocodiles.

    No need for even a solar panel.

    Peace out .. Derek

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