Solutions for loadshedding

[Frosty]

1. Yes and no

For a 24V system there will be lower amp requirements on the cabling but you will most likely need double the batteries for the same capacity. Most batteries are 12V. I would always recommend the higher voltage system though for handling bigger loads.

2. You can go either hybrid or a grid tied + off-grid inverters. Having separate inverters is slightly cheaper than a proper hybrid inverter. With the "hybrid" systems between R10-R15k they dont do blended power so if the load demand is higher than what it can supply from a *single* source it will just ship the entire load off to the grid. Proper hybrid inverters will supply what they can from solar+battery and then pull in the deficit from the grid, this makes a very big difference to how much power you pull from Eskom.

3. Honestly the best place for solar/inverter info is www.powerforum.co.za there are a ton of very knowledgeable people on there who would be able to give better advice.

 

 

Just some advice, if you cant afford to do a full system from the start then look at doing it in phases. Inverter and battery could be charged from the grid until you can add solar panels at a later stage.

 

The biggest long term saving is in batteries, but the downside is that there is a much higher up front cost. You can go for deep cycle AGM batteries but they have a limited lifespan and dont like to be discharged further than 50%. Lithium on the other hand has tons of cycles and can handle deep discharge, it works out a lot cheaper over time but the initial investment is quite high. 

I had a reply ready, very similar to your, but got distracted by work requirements... priorities

[Frosty]

We recently bought a new house, and I want to look at getting a "small" loadshedding setup with the idea of adding onto it at a later stage (batteries and solar panels).

 

To start of the idea is to probably get an inverter between1.5kva and 3kva (pure sinewave), since the idea is to add-on later and I don't want to get to the situation someone explained above, i.e. my inverter doesn't have enough capacity for everything added, probably 2 batteries (either 100/105AH or 150AH) and some solar panels if I can afford it all.

 

There are lots of information, and starting reading up on it I am getting confused, so hopefully someone here can shed some light.

 

1. Is a 24V inverter better than a 12V inverter?

2. My assumption is that I need a Hybrid inverter to use both power from solar and the grid, is this is the case?  If not, what is needed?

3. Anything else I should know, or perhaps a few links to sites I can use to get more information?

 

I will get someone to come and do the installation, etc for me, I just want to know what is happening so that I don't get bullsh**ed into something not needed or not necessarily correct.  Plus I would like to do additional add-on's myself in future (if possible).

Some useful replies already, so no point in me posting my original response.

A few extras to consider before you go down the long rabbit hole.

 

Note: TL;DR - just ready the bold bits.

1. If you have a flexi-loan facility on your bond, consider using it. It avoids having to apply for finance, and your home loan is/will probably (be) at a better rate;

    

2. I'm saving about R760 per month by not having to buy units (electricity) every month, and I can live off the 100 free units allocated to me monthly by the council. I occasionally use the grid to charge the battery, in case I wake up to a dark, overcast morning and the early morning sun can't charge the battery.

    

   I'm pumping R800 back into the loan every month to payback my investment. With the likely increases for the cost of electricity, I will break even earlier than anticipated, and then the real savings will start. By that time, I would hopefully have replaced the lithium battery once.

    

   Don't let people fool you into saying that lithium lasts 15-20 years (6000-7000 cycles). I've yet to see anyone guarantee for longer than 10 years, and most are at 5 years. It will still work after 10 years, but not at the same efficiency you had when new. The nice thing is that good batteries are able to be run in parallel and talk to each other (including the inverter). Remember that "Goed koop is duur koop".

    

3. Run what you can while the sun shines:
   • my pool runs between 10:00 - 14:00;
   • washing & dishwasher machines from 07:00 - 10:00;
   • garden engineer comes once every fortnight; lawnmower on once dishwasher or washing machine has finished;
   • vacuum cleaner and ironing after 14:00 but off before 16:00.
   • The peak power cycle of these appliances are all different, but if they all run at the same time, then I would be over the limit of my inverter, and it would sound the alarm;

      

   • The rest of the house is minimal and can run at the same time as the above, eg. coffee machine pulls 1.3kW for less than a minute.

      

   • I was given a portable energy meter by my installer that shows me what I am using in the moment, and also sounds an alarm when I reach +/- 88% of max capacity. Sure, I can always use the grid to pull the excess quantity, but then it simply erodes the savings I get from keeping everything off grid for as long as possible;

      

   • I have a full gas oven, and my geyser is on the old-school solar water heating system (the 10W pump to circulate the water doesn't use too much). I've heard people say a heat pump is better than solar water heater - I'm not sure, the investment is the same and I haven't had much of a problem in the last 7 years, except for 2 hours a day in winter. That's what the accumulation of those monthly 100 free units will be used for.

      

   • If you must run your geyser on solar, get a smaller-sized element and run it over a longer period, eg. a 2kW element running for 2-3 hours will do the same as a 3.5kW element running for 1.5 hours. Water heats up at the rate, but will take longer with less va-va-voom. If you're on the grid, there will be no benefit, as you would when spreading the load over the available sunlight hours.

As some have already commented, www.powerforums.co.za has a lot more knowledge than I could every hope to know. My knowledge is mostly from experience I have from using my system for a month, a little bit of research, and the knowledge I got from my installer.

[TheoG]

I started with an 2500 W (5000 peak) pure sine inverter with 4 x 180 Ah batteries (AGM).  I connected them in series + parallel since my inverter is 24V input.

 

My DB is also wired to auto switch (relay) between grid and inverter, cutting out the geyser & stove from the circuit when on inverter.

 

The plan is to later add some solar panels, but for now I simply keep my batteries charged and that get me through most power cuts.  From previous outages, look like I can get to about 12 hours until my battery voltage will drop below 22V.

 

When that happen, my geni is also wired into the DB with a manual switch over between inverter and geni.

 

So far so good.

Edited January 19, 2021 by TheoG

[LazyTrailRider]

Some useful replies already, so no point in me posting my original response.

A few extras to consider before you go down the long rabbit hole.

 

Note: TL;DR - just ready the bold bits.

1. If you have a flexi-loan facility on your bond, consider using it. It avoids having to apply for finance, and your home loan is/will probably (be) at a better rate;

    

2. I'm saving about R760 per month by not having to buy units (electricity) every month, and I can live off the 100 free units allocated to me monthly by the council. I occasionally use the grid to charge the battery, in case I wake up to a dark, overcast morning and the early morning sun can't charge the battery.

    

   I'm pumping R800 back into the loan every month to payback my investment. With the likely increases for the cost of electricity, I will break even earlier than anticipated, and then the real savings will start. By that time, I would hopefully have replaced the lithium battery once.

    

   Don't let people fool you into saying that lithium lasts 15-20 years (6000-7000 cycles). I've yet to see anyone guarantee for longer than 10 years, and most are at 5 years. It will still work after 10 years, but not at the same efficiency you had when new. The nice thing is that good batteries are able to be run in parallel and talk to each other (including the inverter). Remember that "Goed koop is duur koop".

    

3. Run what you can while the sun shines:
   • my pool runs between 10:00 - 14:00;
   • washing & dishwasher machines from 07:00 - 10:00;
   • garden engineer comes once every fortnight; lawnmower on once dishwasher or washing machine has finished;
   • vacuum cleaner and ironing after 14:00 but off before 16:00.
   • The peak power cycle of these appliances are all different, but if they all run at the same time, then I would be over the limit of my inverter, and it would sound the alarm;

      

   • The rest of the house is minimal and can run at the same time as the above, eg. coffee machine pulls 1.3kW for less than a minute.

      

   • I was given a portable energy meter by my installer that shows me what I am using in the moment, and also sounds an alarm when I reach +/- 88% of max capacity. Sure, I can always use the grid to pull the excess quantity, but then it simply erodes the savings I get from keeping everything off grid for as long as possible;

      

   • I have a full gas oven, and my geyser is on the old-school solar water heating system (the 10W pump to circulate the water doesn't use too much). I've heard people say a heat pump is better than solar water heater - I'm not sure, the investment is the same and I haven't had much of a problem in the last 7 years, except for 2 hours a day in winter. That's what the accumulation of those monthly 100 free units will be used for.

      

   • If you must run your geyser on solar, get a smaller-sized element and run it over a longer period, eg. a 2kW element running for 2-3 hours will do the same as a 3.5kW element running for 1.5 hours. Water heats up at the rate, but will take longer with less va-va-voom. If you're on the grid, there will be no benefit, as you would when spreading the load over the available sunlight hours.

As some have already commented, www.powerforums.co.za has a lot more knowledge than I could every hope to know. My knowledge is mostly from experience I have from using my system for a month, a little bit of research, and the knowledge I got from my installer.

 

All very good points which echo my experience.

 

On the Li-ion lifespan: My approach is that battery tech will be drastically better 5-7 years from now, so even though my 10/7kWh Freedom WON battery has a 10yr guarantee if used at an average of 70% DoD, I mostly klap it down to 25% or even 20% in winter (when there is no loadshedding).

 

 

Yes, it was expensive at R95k odd, but I'm thinking that I'll rather squeeze every single bit of performance out of it short-term because it's quite possible I'll be able to buy something new double that capacity for the same price 7 years from now and in the process neatly upgrade my overall lack of reliance on whatever the grid state is at that point.

 

EDIT: I see the new model is 18 months later already down to R70k and guaranteed at 10/8, so point proven!

Edited January 19, 2021 by LazyTrailRider

[Rocket-Boy]

All very good points which echo my experience.

 

On the Li-ion lifespan: My approach is that battery tech will be drastically better 5-7 years from now, so even though my 10/7kWh Freedom WON battery has a 10yr guarantee if used at an average of 70% DoD, I mostly klap it down to 25% or even 20% in winter (when there is no loadshedding).

 

 

Yes, it was expensive at R95k odd, but I'm thinking that I'll rather squeeze every single bit of performance out of it short-term because it's quite possible I'll be able to buy something new double that capacity for the same price 7 years from now and in the process neatly upgrade my overall lack of reliance on whatever the grid state is at that point.

 

EDIT: I see the new model is 18 months later already down to R70k and guaranteed at 10/8, so point proven!

Yup, by the time a lithium battery is at end of life there will be much better tech or the pricing will have come down a lot.

Between glass electrodes and super caps there are quite a lot of developments being commercialized at the moment.

You can build a DIY 6.1kwh Li-FE battery pack for around R19k which already is a really good price. Pre-built they are coming in at R27k so even that isnt too bad considering what battery storage cost a year or two ago.

[PieterJvR]

Snip

 

 

Snip

 

 

Snip

 

 

Snip

 

Thank you very much everyone for all the information, I will go read up a bit more and save some more to ensure I put something decent in to start off with.

 

One question which one of you might be able to answer, I read somewhere that alarm system beams only "like" 12V, does that mean I shouldn't even bother to look at higher voltage inverters? Or can additional converters, etc be installed to cater for something like this

[TheoG]

Yes most alarms run on 12V.  imho, better to keep your alarm system/beams on a separate battery.

 

The higher the inverter input voltage the better (more efficient, hence less energy loss).  I'm on 24V but 48 or even 96V would be better, but that imply a lot of batteries (x 12V) to get there which is expensive.

[Frosty]

Thank you very much everyone for all the information, I will go read up a bit more and save some more to ensure I put something decent in to start off with.

 

One question which one of you might be able to answer, I read somewhere that alarm system beams only "like" 12V, does that mean I shouldn't even bother to look at higher voltage inverters? Or can additional converters, etc be installed to cater for something like this

How are you currently running it? I bet through a 12V battery which is plugged into a transformer/adapter on a plug? The plug feeds off the grid which is 240V (give or take some volts up/down, at close to 50Hz and as many Amps as your main isolator switch is rated for, eg. 63A.

 

The inverter won't make a difference to your alarm/beams. The conversion is done at that transformer/adapter that would remain plugged into the 240V plug point. The inverter merely converts DC from the panels/battery and converts it into AC for you to use as if it were the grid. 

[PieterJvR]

How are you currently running it? I bet through a 12V battery which is plugged into a transformer/adapter on a plug? The plug feeds off the grid which is 240V (give or take some volts up/down, at close to 50Hz and as many Amps as your main isolator switch is rated for, eg. 63A.

 

The inverter won't make a difference to your alarm/beams. The conversion is done at that transformer/adapter that would remain plugged into the 240V plug point. The inverter merely converts DC from the panels/battery and converts it into AC for you to use as if it were the grid. 

 

Thank you, that answers my question.  And yes it runs off a 12V battery currently

[Rocket-Boy]

Thank you, that answers my question.  And yes it runs off a 12V battery currently

I think all alarm systems run off 12v DC, I have the charger plugged into my inverter and it work perfectly, the alarm system can handle around 24 hours of no power before the battery dies but with it connected to the inverter there are no issues with outages.

[PieterJvR]

I think all alarm systems run off 12v DC, I have the charger plugged into my inverter and it work perfectly, the alarm system can handle around 24 hours of no power before the battery dies but with it connected to the inverter there are no issues with outages.

 

My alarm stays on for quite a while on battery - probably not 24 hours but that might be due to the 3 outside beams.  However I have seen during the last round of loadshedding the alarm battery doesn't manage to charge enough to remain on during subsequent loadshedding slots - it does not help that we have 2.5 hour slots that can occur 5 hours apart - after a few days I start getting low battery alerts, and it even died once.  I have replaced the battery with a gel battery which lasts longer but the inverter setup is definitely the solution and / or end goal.

[Frosty]

My alarm stays on for quite a while on battery - probably not 24 hours but that might be due to the 3 outside beams. However I have seen during the last round of loadshedding the alarm battery doesn't manage to charge enough to remain on during subsequent loadshedding slots - it does not help that we have 2.5 hour slots that can occur 5 hours apart - after a few days I start getting low battery alerts, and it even died once. I have replaced the battery with a gel battery which lasts longer but the inverter setup is definitely the solution and / or end goal.

Here is my consumption for the following devices/appliances:

 

 

Router, fridge, pump for solar water heater, alarm and two sets of lights. Total usage per day was 6.4kWh (while away on holiday). Everything else was off. It means I am able to run all of this for 16 hours on my battery.

 

Ignore the following:

1 The blue part of the graph as this was the solar array recharging the battery;

2. The solar water heater was on holiday mode, so it runs like normal when the sun shines, but also circulates the water at night to bring the geyser temperature down, as we aren’t using the geyser when away.

[Frosty]

This will give you an idea of what is required to keep your alarm connected, all of the time, plus a few other devices/appliances. The smaller the inverter/battery combo, the less time you can run it before it shuts down to save the battery from 100% discharge. That’s why you need solar panels to keep it charging while in use.

[PieterJvR]

This will give you an idea of what is required to keep your alarm connected, all of the time, plus a few other devices/appliances. The smaller the inverter/battery combo, the less time you can run it before it shuts down to save the battery from 100% discharge. That’s why you need solar panels to keep it charging while in use.

 

Thanks for all the info, appreciate it! 

[Rocket-Boy]

This will give you an idea of what is required to keep your alarm connected, all of the time, plus a few other devices/appliances. The smaller the inverter/battery combo, the less time you can run it before it shuts down to save the battery from 100% discharge. That’s why you need solar panels to keep it charging while in use.

I still really want to put a proper system in place, Im saving up and keeping an eye on new developments.

For now I have a 1000W portable inverter with 2x 120AH AGM batteries in, it holds my alarm, router, fibre ONT, unifi access points, pc, TV and Roku for about 6 hours so it keeps everyone happy during loadshedding.

 

On days like these I just get sad about all the solar power Im not getting

[bertusras]

 

Another day in Sunny South Africa