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Thread: 4 days without power again

  1. #1
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    4 days without power again

    Fortunately in SA, all some of us take from these experiences, is a smarter solution. You can sit and smash away at your keyboard all day, blame the government, blame Eskom, the ward councillor, the poor electricians who had a weekend of hell in the pouring rain and rivers of water, trying to get things working. While we lay in a warm bed with a hot coffee and a warm beacon, eggs and toast breakfast, smashing away at our keyboards, enjoying our favorite Netflix moving, thinking of who else to blame.

    What did we learn:

    Solar, inverter and flooded lead acid is not the solution, why not,

    The first one is easy, no sun no power.

    The second reason, flooded lead acid batteries are pretty useless, they can only be discharged a small percentage without reducing the cycles (lifespan), in desperate times, dropping it to 10 % DOD is what you have to do to keep your security systems and stuff operational.

    The bigger issue is charge rate, if you drop the battery to 10 % DOD, you need to charge it again and that's were it becomes an issue. A 100 amp/hr FLA battery will take 10 hours @ 10 amps to charge. Which means if it rains non stop for 5 days, you still have to run a generator for 10 hours (a gel battery can be charged a little faster if the inverter is setup right)

    Some might say, well get a lithium battery, and would be partly correct, because the charge rate could be better using a 0.5C lithium battery.

    You still have to run the generator, but a lot less time. At the current fuel cost, around R500 for the day, from 8 am till 6 pm.

    So what would be the solution, a 1C battery, because you can charger the battery at double the current, which reduces your down time, fuel in your generator and less noise pollution, because we are all considerate about the noise, someone should message those inconsiderate people who install them far away from their own house, but right next to your bedroom window.

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    Was spending R15 K on a 3 KVA axpert inverter with 2 x 100 amp/hr gel batteries a wise choice, not if you were one of the many who sat without power for 4 days and without a generator.

    Firstly lets clear up a myth, installing an inverter and batteries will save you money, no it doesn't save you a cent, unless you have PV panels to charge the batteries, in fact it will cost more money to keep the system operating and it will cost even more money to recharge the batteries, so you will see and increase in your electricity bill.

    Can you sell your generator once you install an inverter and batteries, no, not even if you install PV panels, unless you take a second bond on your house, spend around R250K + which by the way you will need another second bond to replace the batteries before you have even paid off the first set of batteries.

    How long will a 3 KVA inverter with 2 x 100 amp/hr gel batteries last? IF you use less than 500 watts of the 3000 watts you might be lucky to keep the power on for 2-3 hours.

    If your installer has setup the unit correctly, the battery cutoff will be set right, which will extend the life/cycles of the battery, however you will loose battery capacity.

    Setting up the inverter correctly is key to getting optimal performance out your system, something not too many people know how to do.

    Without remote monitoring is like riding an MTB down a trail in the dark without a light.

  3. #3
    Site Caretaker Dave A's Avatar
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    I spent yesterday afternoon tweaking my inverter setup to optimise some generator top-up. Discovered a couple of things along the way -

    1. With the Growatt inverter, you set mode to Appliances, UPS or Generator. Set it to Generator when you are connecting a generator and it will still feed the load while recharging the battery.
    2. Change the battery charge current to suit the power available from the generator. I could triple up the charge current to get the generator working at 80% of capacity.
    And yes, thank goodness for decent Lithium batteries when it comes to generator run time

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    Although at the moment people can benefit from reduced power reliance on ESKOM by installing solar, ESKOM is currently fighting for tariff changes, one of which is that solar users must pay at a higher tariff rate than others as, during peak power periods at night or on cloudy days, these users are drawing from the grid power and ESKOM has to cater for them in their power production planning. ESKOM cannot just up power production on any given day because it’s cloudy—they need to cater for this capacity all the time to be able to produce it when needed. So, the long-term outlook for solar users is that they will probably be paying much more for power than non-solar users in the future.

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    Quote Originally Posted by Alfred M View Post
    Although at the moment people can benefit from reduced power reliance on ESKOM by installing solar, ESKOM is currently fighting for tariff changes, one of which is that solar users must pay at a higher tariff rate than others as, during peak power periods at night or on cloudy days, these users are drawing from the grid power and ESKOM has to cater for them in their power production planning. ESKOM cannot just up power production on any given day because it’s cloudy—they need to cater for this capacity all the time to be able to produce it when needed. So, the long-term outlook for solar users is that they will probably be paying much more for power than non-solar users in the future.
    Then you need to get smart and find a way to take your solar system completely off grid and disconnect it from the mains In my case my workshop, office and outbuildings will be disconnected from the grid and only a small portion of my house will be connected to the grid.

    * I have a backup generator for my solar system *

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    Quote Originally Posted by Alfred M View Post
    . So, the long-term outlook for solar users is that they will probably be paying much more for power than non-solar users in the future.
    The way I understand it , is that they want all users , especially domestic to go onto time of use tariff

    The problem is evening and morning peaks - Hence the reason for the load shedding in the evening

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    My view at the moment is a combo of Gas for cooking and heating, solar for electronics with batteries and genny for cloudy days...

    I don't know enough about gas and price to run etc but that is my current thought process...

    My buddy has a gas geyser and it's 45watts to run it when in use and he runs it off his little inverter...

    He also has gas hob... So a small adjustment to boiling water and no oven and he can be off grid with a small system

    Sent from my CPH2197 using Tapatalk

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    Diamond Member Justloadit's Avatar
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    It is extremely costly to go completely off grid.

    One of the issues is that the use of hot water has to be carefully observed to get the most out of the sun based heating periods.
    I have a dual geyser PV based water heating system, which is split between the kitchen and the bedrooms, giving me 300 litres of hot water every day with dedicated panels for this application.
    Most days both 150L geysers end up at 65°C, however when it rains, I may get 40-50°C from both depending on the amount of cloud cover if all day or not.
    I do have a mains back up when i require hot water. I usually set up the cut out at 50°C when running off mains, and has been adequate for my use.
    Depending on the start temperature, I save between 7,5kW to 14kW per day.
    My pool pump, which draws 1kW, runs of the inverter during the day between 10AM to 3PM when the sun mostly shines.

    I then have a 5.5kW hybrid system with 10kW Lithium battery pack, and 2.6kW of PV panels.
    I still use quite a bit of power from the grid, most days 50% solar, and 50% from mains. Totaling between 25 to 30kWH a day, when there is full sun shine whether winter or summer.
    I could improve the amount from solar by increasing the number of PV panels and battery back up, so that less dependence on the grid.

    I also have an 11kW generator as further back up.

    I have noted a 50% saving on my mains bill.
    My current cost for the hybrid and PV geyser is around R120K.
    To go completely off grid, is far more expensive them maintaining some use from the grid.

    Another very important point to note, that to get the best use of the PV solar water heating hot water storage, requires that the geyser be replaced with the latest models, and cladding all the pipes to and from the geysers, which have between 0.5 to 1°C of heat loss per hour, as opposed to the older geyser that use 3 to 4°C per hour, which greatly influences how long you can store the heated water, especially in winter.
    Victor - Knowledge is a blessing or a curse, your current circumstances make you decide!
    Solar pumping, Solar Geyser & Solar Security lighting solutions - www.microsolve.co.za

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    Quote Originally Posted by Justloadit View Post
    It is extremely costly to go completely off grid.

    One of the issues is that the use of hot water has to be carefully observed to get the most out of the sun based heating periods.
    I have a dual geyser PV based water heating system, which is split between the kitchen and the bedrooms, giving me 300 litres of hot water every day with dedicated panels for this application.
    Most days both 150L geysers end up at 65°C, however when it rains, I may get 40-50°C from both depending on the amount of cloud cover if all day or not.
    I do have a mains back up when i require hot water. I usually set up the cut out at 50°C when running off mains, and has been adequate for my use.
    Depending on the start temperature, I save between 7,5kW to 14kW per day.
    My pool pump, which draws 1kW, runs of the inverter during the day between 10AM to 3PM when the sun mostly shines.

    I then have a 5.5kW hybrid system with 10kW Lithium battery pack, and 2.6kW of PV panels.
    I still use quite a bit of power from the grid, most days 50% solar, and 50% from mains. Totaling between 25 to 30kWH a day, when there is full sun shine whether winter or summer.
    I could improve the amount from solar by increasing the number of PV panels and battery back up, so that less dependence on the grid.

    I also have an 11kW generator as further back up.

    I have noted a 50% saving on my mains bill.
    My current cost for the hybrid and PV geyser is around R120K.
    To go completely off grid, is far more expensive them maintaining some use from the grid.

    Another very important point to note, that to get the best use of the PV solar water heating hot water storage, requires that the geyser be replaced with the latest models, and cladding all the pipes to and from the geysers, which have between 0.5 to 1°C of heat loss per hour, as opposed to the older geyser that use 3 to 4°C per hour, which greatly influences how long you can store the heated water, especially in winter.
    I agree a small entry-level off-grid system now starts from around R250,000, while a premium system with more autonomy could run upwards of R650,000.

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    People taking seconds bonds on their house to pay off a system over 25 years, which could only last 5-10 years and then has to be replaced again, mmm I start wondering about the real reason for load shedding and power cuts.

    I am sure someone will come up with the figures and reason behind all this debt being created.

    If other countries have offered rebates and incentives to the public, yet we are looking at penalties for solar, what is really going on?

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