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Doom5003
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Good day to all, first post so hope it is in the right place.

I have been reading some post in hopes to learn more and get some questions answered but feels like the more i read the less i actually know.

I should probably start with whey i came here to being with.

So, loadshedding, the bane of everyday life. Firstly i would like to start small but also have the option to expand.

Some background:

The household uses about 16-17 unit a day (not sure what that is in watts usage), we try to keep it as low as possible without making life unbearable.

To start, im not looking to go completely off-grid (for now), would just like to run a TV 48" LED, 2 routers, a fan or 2 and 2 LED lights for when ever loadshedding hits.

The plan is to expand on this and add some solar panels , having them charge the batteries (lithium hopefully) and when full help supplement the house, not sure if this is even possible.

So grid and solar during the day, grid only during the night and then batteries as backup for loadshedding or power failure.

It would be much helpful if the switching between solar, grid and batteries were auto mated, since i am away on work alot and wife isnt to trustworthy with electronics, trying to explain how to switch between two different wifi's over the phone was hard enough.

 

Was thinking starting with an inverter and one battery and then add some more down the line until the battery capacity is enough to support the essentials, then add the solar to charge those and start saving money.

Any advice on what brands of batteries are great, links to products even better, and what inverter would be advised.

Budget wise, no idea. Nothing saved as of yet, first like to see what is recommended at what price. So will most likely only be buying near the end of the year depending on numerous factors. Hard to budget and plan for more than a few months when you have a 2 year old running about.

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1 hour ago, Doom5003 said:

The household uses about 16-17 unit a day (not sure what that is in watts usage), we try to keep it as low as possible without making life unbearable.

A unit is a KW/h. IE equivalent to using 1 KW continuously for an hour.

Where are you? Different municipalities have different load shedding strategies EG CT sheds for 2 hours, JHB twice as long but less often. Obviously this has a bearing on how much battery you need initially.

That said, the more the better. I used to run an inverter and batteries, and I went big on batteries. This made little difference for a load shed, but when it was a load shed and the local substation popped on restart or, as did happen, somebody dug up a power cable out of carelessness and we had an 18 hour outage, then the extra battery capacity helped.

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1 hour ago, Doom5003 said:

It would be much helpful if the switching between solar, grid and batteries were auto mated, since i am away on work alot and wife isnt to trustworthy with electronics, trying to explain how to switch between two different wifi's over the phone was hard enough.

If all the devices you want to back up are in one room, or close enough to the inverter that you can run extension leads that people won't trip over then no problem. Otherwise you'll need to wire this into the house so that it feeds the DB or part of the DB. But almost all systems you buy new these days will switch automatically. Some of them can send a signal to a generator to start it up (assuming the gennie can receive and act on the signal).

I bought my system from a vendor, and that included installation. The only way we would notice that the power is out now is that the swimming pool pump stops - and we'd only notice that during the day. Yes, there are other circuits that aren't backed up, but we seldom use them. Point is, the change over is automatic and fast, and since the new system doesn't have an audible alarm we don't notice when the change over happens. 

Even with the inverter and batteries we had no flicker of the lights or TV.

The system I have (see my signature) achieves your eventual aim. When there's a load shed our fridges and freezer still run, our lights stay on, the security system stays up etc. Plus our reliance on the grid is reduced because we get lots of solar power most days, and so on a sunny day even when the grid is available, we run mostly off solar (whilst recharging batteries)

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44 minutes ago, Bobster said:

A unit is a KW/h. IE equivalent to using 1 KW continuously for an hour.

Where are you? Different municipalities have different load shedding strategies EG CT sheds for 2 hours, JHB twice as long but less often. Obviously this has a bearing on how much battery you need initially.

That said, the more the better. I used to run an inverter and batteries, and I went big on batteries. This made little difference for a load shed, but when it was a load shed and the local substation popped on restart or, as did happen, somebody dug up a power cable out of carelessness and we had an 18 hour outage, then the extra battery capacity helped.

Upington, Northern Cape. Loadshedding is (depending on stage) between 1 or 2 times a day for 2.5hrs a day.

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37 minutes ago, Bobster said:

If all the devices you want to back up are in one room, or close enough to the inverter that you can run extension leads that people won't trip over then no problem. Otherwise you'll need to wire this into the house so that it feeds the DB or part of the DB. But almost all systems you buy new these days will switch automatically. Some of them can send a signal to a generator to start it up (assuming the gennie can receive and act on the signal).

I bought my system from a vendor, and that included installation. The only way we would notice that the power is out now is that the swimming pool pump stops - and we'd only notice that during the day. Yes, there are other circuits that aren't backed up, but we seldom use them. Point is, the change over is automatic and fast, and since the new system doesn't have an audible alarm we don't notice when the change over happens. 

Even with the inverter and batteries we had no flicker of the lights or TV.

The system I have (see my signature) achieves your eventual aim. When there's a load shed our fridges and freezer still run, our lights stay on, the security system stays up etc. Plus our reliance on the grid is reduced because we get lots of solar power most days, and so on a sunny day even when the grid is available, we run mostly off solar (whilst recharging batteries)

Thanks, ill have a look at that system of yours.

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1 hour ago, Doom5003 said:

Thanks, ill have a look at that system of yours.

Our useage was averaging out about 14 kw/h a day. So not a lot less than you, and the system could take more load as most days the battery is recharged by midday and the Goodwe derates the solar panels so that they just service the load.

It still retains a grid connection, so we can play it all ways. Most days it produces most of our power whilst additionally giving us protection against outages. The battery always gets us through the night and then unless the weather is foul we get solar in the morning.

We can also run it like a UPS and use grid to charge up the batteries, but increasingly I am leaving to it's own devices.

You can have rules (and this is not unique to Goodwe) like "only run the battery down by 60% if there is grid power available". So that means we would always have 40% in the battery if the power goes out.

Generally I think what you are aiming towards is a hybrid system. I have a Goodwe, but it's not the only such. So I think what you need as a foundation for the system is an inverter that can be run in that mode. Then you add panels, increase batteries with time and budget.

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Hello @Doom5003,

With the TV is there a DSTV decoder, additional audio or TV audio only? For the Wifi will you also have PCs or laptops running? That will determine what kind of system you need. Pedestal fans or ceiling fans?

VERY rough estimates here:

  • TV - ~150W
  • Ceiling fan ~60-80W
  • Pedestal fan ~75W (high speed)
  • Router ~15W
  • LED light 14W (if standard ceiling light)

Given the above as, once again, VERY rough estimates then:

  • 1x TV = 150W
  • 2x Ceiling fan = 160W
  • 2x Router = 30W
  • 4x LED light = 56W (added 2 extra lights because, you know, bathroom and so on)

Total = 396W, let's round to 400W per hour of use, given all devices are used simultaneously.

You will need a 600-800W (continuous, not peak) pure sine wave inverter. Most inverters I know in this size will not allow you to expand to solar later on though.

To power your 400W load for one hour with a lead acid battery you will require roughly a 70Ah battery, so 200Ah battery to net 3 hours at 50% depth of discharge. Given most load shedding is 2-2.5 hours you will use probably about 40% DoD and extend your battery life.

The caveat with the above scenario is you will likely require a separate battery charger as, once again, these smaller inverters do not usually come as inverter / charger combos and even if it did will probably be insufficient to charge a 200Ah battery.

You could go to a larger (or more expensive) inverter / charger straight away and cut out the separate battery charger altogether. You would need 20-40A charge current with any separate charger, 20 being minimum.

Once you go to a larger inverter, check the battery input voltage for that specific inverter because 1500W and above are usually 24V (meaning 2x 12V batteries) and 3000W upwards are usually 48V (so 4x 12V batteries or at least 1x 48V Lithium).

EDIT: I see above you have already kitted some nice things, was not sure how soon you intend to upgrade or if you wanted a basic working system for now. The Pylontech are good batteries.

Edited by netstrider
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