Load Shedding Solution for South-Africa – Eskom DIY UPS

With the multiplus II and grid feed, do you need an energy meter like in your diagram, or does the external current sensor clamp work?

Thank you

I see the allure of having a very simple system without solar panels, but it makes for a very, very expensive system when you do that. And the multiplus is overkill if it is only going to run a few loads. It doesn't really make any sense to try to run the whole house with a system like this due to the small amount of battery storage. So I see it as a bit of a mix of components that don't fit well with each other at small scales.

How about this. I'll describe a system revolving around 24V but the same thing can be done at 48V for about the same price except the battery charger solution might have to be a bit different (Victron doesn't make a low-cost 48V battery charger).

* 2 x Residential solar panels in series (300W or higher each for 600W+ total). Roughly $500 in total (probably less). This will work for both 24V and 48V system voltages. The open circuit voltage needs to be less than around 85V via the labeling on the panels, to be safe. As I specify Victron 100/20 charge controllers below (100V maximum VOC, but subtract a bit for margin).

* Victron SmartSolar 100/20 charge controller. Roughly $80. This will also work for 12V, 24V, or 48V system voltages (the 75/15 is only 12V or 24V). Each unit caps out at roughly 500W at 24V or 1000W at 48V. A bit more as the battery voltage rises. You can have as many as you need… no need to parallel larger panel configurations.

(unit is setup with a normal charge profile for the battery and the series configuration for the panels will work for both 24V and 48V systems as well).

(again, I'm assuming a small-scale system, not a huge solar system).

* Victron Phoenix 500VA 24V inverter: $150 (Victron also makes a 48V for about the same). Increase to 800VA if you need more power but the whole point is to only power the fridge and a few small loads. The smaller the inverter you use that is still sufficient for the loads, the less idle power the inverter will consume. The smaller inverters consumes roughly 5W at idle.

(this will depend on the fridge's startup needs. The Phoenix is pretty beefy for surge loads but if you are worried you might have to up it to the more expensive 800VA version).

(note: Some phoenix inverters have a GFCI or AFCI built-in, but the fridge-startup might trip it so be prepared to change it out for a normal plug and put the real protection in your breaker box instead… or better, buy a Phoenix that just has a normal plug and not a GFCI/AFCI).

* Victron Energy Blue Smart 24V 12A Battery charger: $180. There is no decent Victron equivalent for 48V so you are on your own in terms of finding a grid load-support solution at 48V. I use a complex setup with a Mean Well HLG-320H-54A power supply run through four schottky diodes in parallel on my 48V system.

(Basically for the battery charger I put the Victron charger in "power supply" mode and just set the voltage to a decent load-support level that still leaves room for the solar to handle most of the energy needs. For example, I'll set the power supply to roughly 26.2V on a 24V system or 52.5V on a 48V system).

(While you can have the power supply fully charge your battery, you want to leave room for the solar to provide most of the energy rather than the grid).

* One 100Ah x 25.6V LiFePO4 battery: Roughly $500. Can easily be expanded by paralleling more batteries. If you go 48V, then the minimum is one 50Ah x 51.2V LiFePO4 battery. Similar price.

(I recommend 2 AWG battery cabling. Up to 2 batteries can be paralleled with one main 120A fuse. If paralleling 4 batteries, a slightly different fusing configuration is needed or one can use thicker cables).

(So, 2560 Wh of storage with one battery, up to 10240 Wh with four).

* Fuses wires, breakers, etc: $300 (same as described in video)

Total: $1710 (USD)

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There are a couple of advantages to this sort of setup.

* Loads are always on the inverter and basically immune to bad grid power.

* Not having a transfer switch is considered a good thing in many situations.

* Relatively cheap discrete components that can be easily maintained when things inevitably break.

* Easily expandable. For the 24V system, up to around 2000W of solar (at least if you stick to 2 AWG battery cabling). For the 48V system, 5kW is easy (again sticking with 2 AWG cabling). And storage can be expanded indefinitely with appropriate fusing as long as the system total amperage is within the cable specs.

* Your grid consumption is lower, saving you roughly $0.50 (USED) a day = $180/year, or a 10-year break-even on the equipment. This is better than not having a break-even at all without solar.

-Matt

I grew up in Swaziland in the early 60's. In those days we had a paraffin fridge. A bit of a smelly old thing, but pretty fool proof

Thx for sharing! i have a question. how do you size the breaker feeding the inverter when the grid power is present? because it will be actualy used the charge the batteries and power the loads connected on out 1 and 2 when the inverter is in bypass mode.

My man, been a subscriber for a while. Happy you making content for this shitty country 😂