Interesting - so it's a single contactor, and you've never blown a washing machine motherboard, etc?

What is the most "inductive" load that you're powering?

The "worst" things that I plan on powering are my washing machine, and a small-ish (1KW) aircon. If a single contactor does the job for you, then I guess I'm OK to risk that too.

9 minutes ago, Ben Harper said:

What is the most "inductive" load that you're powering?

Everyday it switches over while the deepfreeze + fridge-freezer combo + sometimes Samsung inverter washing machine and Samsung dish-washer depend on usage at time. Then the small stuff like tv, wifi, decoders, gate motor, alarm, electric fence, cctv’s is always on and two pc’s that hardly ever gets shut down.

A week ago I lost a small power supply for my cctv system, I’m not sure why but this has been working non stop for about 3years now so I’m not really concerned about it.

 

Thanks - that's great to know. If the CCTVs are always on, then it's hard to imagine how that could have been affected.

1 hour ago, Gerrie said:

Everyday it switches over while the deepfreeze + fridge-freezer combo + sometimes Samsung inverter washing machine and Samsung dish-washer depend on usage at time. Then the small stuff like tv, wifi, decoders, gate motor, alarm, electric fence, cctv’s is always on and two pc’s that hardly ever gets shut down.

A week ago I lost a small power supply for my cctv system, I’m not sure why but this has been working non stop for about 3years now so I’m not really concerned about it.

 

Garrie, Funny thing, i lost a small power supply to on my DVR because of the switching. Every time i switch the DVR restarts. Then the other day the power supply said hello!!! I change it over to new power supply and now when i'm switching the DVR don't restart so seems to me the supply keeps its charge/power a bit longer before dropping. 

On 2020/02/25 at 10:50 AM, Ben Harper said:

Ideally, monitor the available PV power, to figure out when to flip the switch.

I think a normal daylight switch could also be helpful to signal if it is dark and than switch those heavy loads off. But I think it would need a delayed timer to avoid nuisance switching. I read somewhere on the forum someone suggested using a small solar panel with a resistor to signal available pv power for during the day. I don’t now if this would be possible but am curious. It is something I might try in future. 

When I get around to building the Raspberry Pi software, I'll share it here. I'm going to try and source some kind of light sensor, and take some measurements vs available PV wattage.. so that the software can make the right choice.

@Gerrie one more question - where did you buy that contactor, and do you know the exact part number(s)?

3 minutes ago, Ben Harper said:

When I get around to building the Raspberry Pi software, I'll share it here. I'm going to try and source some kind of light sensor, and take some measurements vs available PV wattage.. so that the software can make the right choice.

@Gerrie one more question - where did you buy that contactor, and do you know the exact part number(s)?

The best would be to have a small PV panel as light sensor. And either measure it's OCV, which is proportional to the MPP, or measure the IV curve continually.

4 hours ago, Ben Harper said:

where did you buy that contactor, and do you know the exact part number(s)?

Hi Ben, I ordered these on ebay the seller was arlen&alice , I used a 63A for non essential and a 25A for essential loads

part : TOCT1 4p 63A 2nc 2no 220v

part :TOCT1 4p 25A 2nc 2no 220v

I waited about 2weeks  and price is not bad for them, you can get the hager brand at electro mechanica but the price will be about double the tomzn, also ACDC sell their own brand but the quality is very bad not recommended at all. 

Just trying to understand what you are trying to do. You want to run light and heavy loads off batteries charged by solar with no grid during the day. At night you want to change to grid and run off grid. If there is insufficient solar, you want to disconnect your heavy loads but leave the light loads running still with no grid?

Thanks for the details @Gerrie.

I happened to stop by ElectroMechanica in Cape Town yesterday, and an awesome guy there (Sheldon) sorted me out.

I ended up getting two 25A 2p no 230V Hager contactors (http://www.em.co.za/Home/Modular-Relays-Contactors-Isolators/ERC225_2.html). I only need 4 poles in total, because I'm only switching my heavy loads. "Heavy" in my case is just washing machine and dish washer, so 25A should be enough.

@BoxFish yes that's mostly correct, except I don't understand what you mean by "At night you want to change to grid and run off grid". Also, I really don't care whether I'm on grid or off grid. I just want my light loads to be *always on*, and my heavy loads to be on, so long as there is power, either from grid, or from solar. When there is solar power, then I want as much powered by solar as possible.

3 hours ago, Ben Harper said:

@BoxFish yes that's mostly correct, except I don't understand what you mean by "At night you want to change to grid and run off grid". Also, I really don't care whether I'm on grid or off grid. I just want my light loads to be *always on*, and my heavy loads to be on, so long as there is power, either from grid, or from solar. When there is solar power, then I want as much powered by solar as possible.

Thanks. I wasn't sure if the inverter blended AC and Solar power or if it switched between the two. it looked switched so I wondered how you would get it to run off solar power when the grid was available unless I am completely missing some feature of the inverter.

Edited February 28, 20206 yr by BoxFish

3 hours ago, Ben Harper said:

I just want my light loads to be *always on*, and my heavy loads to be on, so long as there is power, either from grid, or from solar.

This will also mean splitting the DB in two parts with two earth leakages, one EL for grid power loads and one EL for solar powered loads that’s if you want the installation to be compliant.

Reason being when heavy loads are on grid power it needs to be on a earth leakage. And when light loads are on solar they need to be on another earth leakage as all cannot work from one EL.

Thanks @Gerrie, I didn't think about the earth leakage! I can't imagine right now how the wiring will look for this, but I'll try figure it out.

57 minutes ago, Gerrie said:

two earth leakages

Earth leakage breakers (or more properly residual current breakers, RCDs) have become affordable enough that I really think it a good idea to have more than one in your house. In multi-storey houses, that means that problem on one floor does not affect the power on other floors (for example). In my previous house I actually had my lights on their own RCD, so that a problem on a plugs circuit does not plunge me into darkness at night. A Hager RCD (which is fairly decent even it if is not quite ABB quality) is about R350, a good price imho.