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DB set up to prevent tripping


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Hi Guys

 

Please assist. 

I have a Goodwe 5KVA inverter and had initially set up the system on 2 loads i.e essential and non essential with 12 panels. 

I subsequently installed another 7 panels and with the excess power thought I would not be in a situation where during load shedding i would need to prioritise my loads. By this I mean I could still run my geyser and pool pump, but be wary of not exceeding 5kw. I know the inverter is only capable of supplying a max of 5kw. The system was fine, only draw back was that I had power but with load shedding or being off grid I couldn't heat my geyser or run the pool pump. Seemed like such a big waste not to use the power when I could.

Smart idea - I then called an electrician and asked him to change the DB set-up to put all the loads in one...i.e no essential and non essential.

The problem:

Now I have this issue:

My 2kw geyser is on, pool pump of 1kw and the normal house essentials comes to a total of 3400kw.

The minute I put the kettle/hairdryer or anything that pushes the total kw to over 5, the system trips.

Please advise me on what the issue is:

  1. Is the system suppose to be strictly on essential and non-essential loads?
  2. Is there a problem with perhaps the way the electrician has wired it?

I would really appreciate advice as its driving me crazy switching of geyser if I need to use hairdryer etc.

 

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Put the geyser on a Geyser wise or normal timer to heat out of "normal" hours, say 4 am when everyone is sleeping or in the afternoon before everyone gets home from work. In the winter I had to "assist" my EV geyser: I increased the temp to 60 and set the geyser wise to heat between 13h00 and 14h00 after the batteries were full. And also did 30 minutes before 5 in the mornings. 

Everyone is now trained to not have more than 2 "big load" on at the same time. My base load is about 200 to 400watt and with 2 big loads I still am under 5kw. I actually seldom go over 3.5kw lately. 

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@xinath,

https://cbi-lowvoltage.co.za/media-gallery/detail/98/1055

https://www.livecopper-cbionline.co.za/products/energy-control-unit-electronic 

In tandem with timing the pump and the geyser to match solar production:

I suggest two units in series one unit being your hairdryer/kettle circuits having priority over another unit that only allows either your geyser or your pump on simultaneously. - Problem solved.

Applications

  • To control the disconnecting of secondary or non-essential loads such as electrically heated water tanks or under floor heating, during high demand periods
  • Example: When a stove (controlling circuit) is switched on and the current exceeds the rating of the ECU, the supply to the hot water tank (controlled circuit) will be temporarily interrupted. The ECU rating (amp) should be low enough to ensure the timely interruption of the controlled circuit.
Edited by phil.g00
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I was going to make the same suggestion as phil.. (but he did a better presentation!)

Has anyone used these load control units and do they work? (my fear is that they are too slow..) 

I have a bunch of the older LCRs which had been thrown out by somebody. These devices use a bimetallic contact to switch the load when an overload condition exists. These are going to be way too slow (I reckon) for an inverter which will trip immediately when that hair dryer is switched on..

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58 minutes ago, Richard Mackay said:

Has anyone used these load control units and do they work? (my fear is that they are too slow..)

I haven't used them, (there are more modern versions out there on the WWW, I don't know their inards either).

My suggestion to use two units was because I suspected these aren't precision devices, and by prioritizing 3 loads the overload threshold would be far enough away to allow switching.

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1 hour ago, Johandup said:

I'm waiting for a clever solar guy to design and showcase a (cheap enough) system based on a plc to do load management. The possibilities are endless. 

May introduce myself? (Apologies I still don't have a business card..)

You make a good point however. I have seen RE installations which aren't simple to manage. I got talking with a guy running accommodation with a number of cottages that all had regular hot water geysers.He only had a limited amount of RE to power some of the geysers, but not all.. So how to deploy the available power in the most effective way??

I suggested a control system but he didn't jump at it.. 

 

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Also remember that there is a lag between power drawn and how fast it can be given from your solar panels, for that small time difference, your batteries need to carry the load until your PV can supply the load. Also your inverter can handle a short spike but not continuously.

unfortunately you have to spread out your loads. Try to never push it over the limit of 5kw. IMO geyser wise works the best for timing your geyser.

Also the use of “load shedding” relays or similar cheaper relays can help to “block” a big load while another big load is already in progress.

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13 hours ago, xinath said:

The minute I put the kettle/hairdryer or anything that pushes the total kw to over 5, the system trips.

I don't think to put your complete house on the "back up" output is a good thing. You will always have overloading and battery draining issues even with careful management of the big loads. How often do you have load shedding? Why do you want to go off grid sometimes?  

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1 hour ago, Fuenkli said:

I don't think to put your complete house on the "back up" output is a good thing. You will always have overloading and battery draining issues even with careful management of the big loads. How often do you have load shedding? Why do you want to go off grid sometimes?  

I think this is the truth of it. I have the same inverter. It can deliver a steady 4.6 kw, and can burst 20% higher for 10 seconds max. In theory I can run off grid on a sunny day, but if my heat pump and the pool kick in at the same time I'm already a bit more than half way to the inverter's maximum steady output, so if somebody then turns the microwave on or does some ironing I'm getting very close to the limits of the system.

I have done some careful reprogramming of timer switches, but it's hard to foresee and thus mitigate against all circumstances.

Depending on how much you want to spend, you could look at a heat pump for water heating. I had one before I went solar. Now I can see how much it uses V the other regular "guest" geyser in our house. It consumes less than half of the regular geyser.

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20 hours ago, xinath said:

The minute I put the kettle/hairdryer or anything that pushes the total kw to over 5, the system trips.

Do you have a auto change over switch? If not that can be a option so that your power just drop back to grid when a inverter trip occurs, that-way you can deal with a tripped inverter later but at least your not in the dark.

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7 hours ago, Bobster said:

Question: Can the geyser wise device be used to control a heat pump? I like my heat pump a lot, but it's not very programmable. You get 3 programs full stop, with only time of day. No day of week.

Hi, 

Geyserwise basically is a timer with a degree setting.
Example, I set my geyserwise to run from 8:45 - 10:15 to a temperature of 60 degrees Celsius, if it reach that temperature before the end time it automatically cut power until it will drop 4 degrees and will provide power in that block of time again if need to.
If it don’t reach the temperature in that time then it is just off until the next block of time kick in.

So I would say it is not a normal timer like a swimming pool pump timer.

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14 hours ago, Wilfred said:

Hi, 

Geyserwise basically is a timer with a degree setting.
Example, I set my geyserwise to run from 8:45 - 10:15 to a temperature of 60 degrees Celsius, if it reach that temperature before the end time it automatically cut power until it will drop 4 degrees and will provide power in that block of time again if need to.
If it don’t reach the temperature in that time then it is just off until the next block of time kick in.

So I would say it is not a normal timer like a swimming pool pump timer.

Thanks you. I understand the broad strokes of a geyserwise. My heat pump has a control unit with similar functionality BUT only three programs, and all of them by hour of day, not day of week. So I was wondering if there was a way to use a geyserwise instead.

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thank you for all the responses, its much appreciated!!! I should stated upfront that I lack technical jargon and knowledge on all levels lolz

 

Fuenkli....so essentially what I asked the electrician to do was put on all  my loads supply onto the back up and hence the tripping?

Isn't there another "load" that I can use so that I have full use of geyser and pool pump during outages?

We have regular outages lasting 12 hours at a time....so I cringe when I know I have the power but cannot use it!!!

 

Please advise in laymans terms what I need to have done to prevent my tripping going foward.

Is moving my loads back to essential and non essential my only option or is there some other way?

 

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On 2019/11/24 at 6:53 PM, xinath said:

Hi Guys

 

Please assist. 

I have a Goodwe 5KVA inverter and had initially set up the system on 2 loads i.e essential and non essential with 12 panels. 

I subsequently installed another 7 panels and with the excess power thought I would not be in a situation where during load shedding i would need to prioritise my loads. By this I mean I could still run my geyser and pool pump, but be wary of not exceeding 5kw. I know the inverter is only capable of supplying a max of 5kw. The system was fine, only draw back was that I had power but with load shedding or being off grid I couldn't heat my geyser or run the pool pump. Seemed like such a big waste not to use the power when I could.

Smart idea - I then called an electrician and asked him to change the DB set-up to put all the loads in one...i.e no essential and non essential.

The problem:

Now I have this issue:

My 2kw geyser is on, pool pump of 1kw and the normal house essentials comes to a total of 3400kw.

The minute I put the kettle/hairdryer or anything that pushes the total kw to over 5, the system trips.

Please advise me on what the issue is:

  1. Is the system suppose to be strictly on essential and non-essential loads?
  2. Is there a problem with perhaps the way the electrician has wired it?

I would really appreciate advice as its driving me crazy switching of geyser if I need to use hairdryer etc.

 

Hi Xinath,

the Goodwe inverter has a feed-in side (non-essential loads that are not supplied if Eskom is gone) and a Backup side (essential side that continues being feed when you are load shed. From what you have described your sparkie has at best connected everything to the backup side of the inverter..... the inverter if it is the 5kW has a load capacity of 2.5kW on the back up side, so you would be pushing your inverter hard on the backup side to keep your house powered. If the load and backup are connected to the same load I would hope that the system trips otherwise you could be damaging your not so cheap inverter or worse feeding into the grid (the inverter should trip itself and go into a safety mode...)

I see cleverer fellows than I have given several different options on spreading your load , I would only add maybe look at adding a solar water heating system. This can assist lighten the load on the inverter by doing most of the preheating of water during the day most days of the year and you just need to top up with PV/battery power on the really cold days.

on my DB i have split it the circuits that keep the family essentials going (lights, security lights, TV, internet, fridge, microwave, garage door, alarm system and electricity fence) going. with this setup my battery bank can run through the night no issues.

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4 hours ago, xinath said:

We have regular outages lasting 12 hours at a time

ok that changes the picture. To have everything on the back up output of the inverter is however in your situation still to much of a compromise. If you really want/need the nonessential loads to be powered during load shedding you can consider putting them on a changeover switch. At least in this case you only have to manage the loads during load shedding. But please be careful I am not a sparky and not sure if this is ok with the SA electrical code.  

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On 2019/11/26 at 8:41 AM, Bobster said:

Thanks you. I understand the broad strokes of a geyserwise. My heat pump has a control unit with similar functionality BUT only three programs, and all of them by hour of day, not day of week. So I was wondering if there was a way to use a geyserwise instead.

@Bobster if you are looking to introduce the weekly and daily timer to your pool pump maybe consider get the low amp timers (they now have the touch screen type ones) and use that to activate a contactor that will and can manage the current surge and if your pool pump has a high initial startup current that would otherwise quickly burn out the timer.

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7 hours ago, Mad Mike said:

@Bobster if you are looking to introduce the weekly and daily timer to your pool pump maybe consider get the low amp timers (they now have the touch screen type ones) and use that to activate a contactor that will and can manage the current surge and if your pool pump has a high initial startup current that would otherwise quickly burn out the timer.

Thanks @Mad Mike. The heat pump is actually used for our geyser. At the moment, with just three programs available. I have to set it so that our housekeeper has hot water during the day - but she's only there two days a week. Mind you... now we're on solar it's not costing me anything, so maybe I should just chillax.

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On 2019/11/26 at 12:41 PM, xinath said:

Please advise in laymans terms what I need to have done to prevent my tripping going foward.

Is moving my loads back to essential and non essential my only option or is there some other way?

 

I asked my connection (ex SA) in California this question.

He says some inverters have a low voltage relay output built into the unit which can be used to switch off the non essential loads (using a SSR)

If your inverter doesn't have this facility you can add a device like this: https://www.morningstarcorp.com/products/relay-driver/

This will do the same job. Doing it this way should make the system automatic without the need for scheduling of loads on a time slot basis..

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