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Planning a new solar install


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Hey all, 

I'm planning a solar setup for my property with the help of a friend of mine. We have been doing as much research as we can and putting the bits together for the setup. And my friend has been trying to get me to understand some of the principles of electricity and calculations. 😅

Let's start from the beginning: 

Goals:

The goal of the project is to not only overcome load shedding; but to also go as much as possible off grid and reduce the COJ bill. If the solar system fails in anyway; I want to be able to switch over to utility and use that. So a hybrid system is required. 

Requirements

Of course no system can be put together, without getting the requirements down first and measuring how much power we are using on the property. This was done by fitting a power monitor into the DB of the house and then hooking it up to Grafana and a database to keep historical data. So, I know what we use exactly during the day and evenings as well as peak loads. 

Peak: is just over 10Kw 

Average: is 1.2Kw 

And during the day the house generally has a constant load of around 700w - 900w 

The system we have in mind won't cover the peak load, however the house does not use over 5Kw load often, its normally when the geyser is on and the kettle / stove / AC etc. I believe the inverter we have in mind will switch over to utility and pull the full load from there, when it is exceeded; and I am okay with that.

Right so with the above in mind, we had to move on to the hardware and put something together that will stay within the budget. 

Hardware:

Inverter: KODAK Solar Off-Grid Inverter MKSII 5kW 48V
PV Panels: 12x  Canadian Solar 365W Poly KuMax Half-Cell 
Battery: 1 x 
Pylon US3000 3.5kWh Li-Ion 

 

Panels are going to be arranged in 4 strings of three. Giving us around 4300w of generation capacity. With a 70% effective generation, On a good day, we should be able to generate around 3Kw, unless my maths is wrong? 

As for the batteries, the plan there is to add more Pylons to the bank to cover the house for the full night. At the moment, the single battery won't do that. But that's okay it will get us through load shedding for the most part. 

Panels will be mounted on a pitched tilled roof, just ever so slightly off true north by a few degrees. 

Sourcing of hardware:

@Jaco de Jongh Has kindly provided some quotes for the above system, so I will be more than likely sourcing the required hardware from him. Not trusting the online stores too much. 🙃

 

So, that's the general plan for the setup and before I pull the trigger on any of it, I wanted to put this post up and hopefully someone can tell me if I am missing anything or have not considered something. 

Thanks for reading! 

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15 minutes ago, francois said:

The recommended discharge current on 1 x  US3000 is 37A.

37A x 48v = 1.76kw

95952291_CaptureUS3000Spec.thumb.JPG.efd4c76f236f63a0e0c05ffaa6330865.JPG

With a 5kw inverter, when running from batteries it would be easy to exceed the recommended discharge current of the battery.

 

Thanks for that. So, no boiling the kettle when on batteries. For now the battery is there to keep the lights on when the grid has failed during the night. Keeping the big loads off, geyser, stove 9Not on inverter anyway) and Kettle, we will stay under 1kw load. 

Edited by Rclegg
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As part of looking at solar, I would also suggest you look at what are consuming your power. 
For instance looking at your high energy devices like the geyser, stove, kettle, etc. and replacing or optimizing those will normally give you more energy for less than it cost to put in more batteries and more solar panels.
Shifting when those devices use power can also be very beneficial. If your geyser can heat water at times when no one will use the stove/kettle it will reduce the spikes. This is even more important as you are looking to go with an Axpert inverter. Most of those don't blend power, but rather switch the full load to the grid as soon as you go over their max rating. 

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1 minute ago, Louisvdw said:

As part of looking at solar, I would also suggest you look at what are consuming your power. 
For instance looking at your high energy devices like the geyser, stove, kettle, etc. and replacing or optimizing those will normally give you more energy for less than it cost to put in more batteries and more solar panels.
Shifting when those devices use power can also be very beneficial. If your geyser can heat water at times when no one will use the stove/kettle it will reduce the spikes. This is even more important as you are looking to go with an Axpert inverter. Most of those don't blend power, but rather switch the full load to the grid as soon as you go over their max rating. 

 

I've started experimenting with shifting my loads. The geyser for instance can be heated later on in the evening, when the kettle is not going to be used (Generally from 22:00 onwards) I am also planning on installing a gas stove. And almost all the lights in the house are now LED. 

With the power monitoring setup I have in place, I can see exactly when and what causes the spikes of power in the house and how often, with that data I can start to experiment with shifting the load. Right now, I am experimenting with the geyser - it is not on during the day anymore and the wife has not complained about water temp - so can try shift it to head up only from 22:00 to 5 or 6am or so. Will see how that goes. 

 

As for the Axpert (Or its clones) not blending; yep, aware of that and Im OK with it pulling full load from utility when we exceed its max load capabilities. Its not often that it happens during the day. 

 

Thanks for the input, much appreciated. 

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1 minute ago, Rclegg said:

Right, if you discard them 100%. I think recommended is 80% DOD? - which bring that down to 2.6Kw give or take I believe? 

Yes you are correct, I wouldn't take them down that low, it will reduce the cycle life. 

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Just now, francois said:

Yes you are correct, I wouldn't take them down that low, it will reduce the cycle life. 

Pylontech say it will reduce to 4500 cycles. So yeah, a big reduction. I'll make sure to keep to the 80% recommendation to get the most out of them. :) 

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9 minutes ago, Rclegg said:

As for the Axpert (Or its clones) not blending; yep, aware of that and Im OK with it pulling full load from utility when we exceed its max load capabilities. Its not often that it happens during the day. 

The Kodak King OG5.48 will blend. Also 0 seconds switch to utility if need be

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Just now, francois said:

Are you planning on monitoring and controlling the system remotely? 

 

 

Yes, I'd like to get data off the system. Stuff like PV generation for the day and various other data points. I've seen the ICC software and email them to check compatibility with the Kodak inverter. They've confirmed it will work. They also do a Pi4 setup with PylonTech cable to monitor. I wasn't sure if that means I need two Pi4s (One for battery and one for Inverter) Tbh I haven't looked into it a great deal. But yes, I would like to monitor the whole system as much as possible. 

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5 minutes ago, Rclegg said:

 

Yes, I'd like to get data off the system. Stuff like PV generation for the day and various other data points. I've seen the ICC software and email them to check compatibility with the Kodak inverter. They've confirmed it will work. They also do a Pi4 setup with PylonTech cable to monitor. I wasn't sure if that means I need two Pi4s (One for battery and one for Inverter) Tbh I haven't looked into it a great deal. But yes, I would like to monitor the whole system as much as possible. 

It will be one Pi monitoring the battery and the inverter at the same time. A lot of people are monitoring their systems like that, including myself.

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3 minutes ago, Plaashaas said:

The Kodak King OG5.48 will blend. Also 0 seconds switch to utility if need be

 

That's correct. However, the Kings have a limitation of PV array size and max string size due to the MPP range (60VDC - 115VDC) vs the MKSII (120VDC - 450VDC) if I recall correctly. I decided to go with a bigger PV array size and output over the blending option and 0ms transfer - which is why I settled on the MKSII 

Unless I missed something, that's how I understand it. :) 

 

Thanks for the input, much appreciated! 
 

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2 minutes ago, francois said:

It will be one Pi monitoring the battery and the inverter at the same time. A lot of people are monitoring their systems like that, including myself.

Oh, that's cool. Would you mind sharing what sort of data you get out of it and are you able to send that data elsewhere? I have Grafana setup and Home Assistant with various smart devices. It would be cool to get the data int Grafana / SQL DB - and into HA to run other automations - like when PV generation reaches a certain point; turn the pool pump on (Currently the pump is connected to a Sonoff and is controller by Home Assistant) or something like that. 😛 

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4 minutes ago, Rclegg said:

Oh, that's cool. Would you mind sharing what sort of data you get out of it and are you able to send that data elsewhere? I have Grafana setup and Home Assistant with various smart devices. It would be cool to get the data int Grafana / SQL DB - and into HA to run other automations - like when PV generation reaches a certain point; turn the pool pump on (Currently the pump is connected to a Sonoff and is controller by Home Assistant) or something like that. 😛 

There are quite a few members that have integrated their systems with HA, they can even control their inverters via HA. Maybe check out the Home Automation discussions:

https://powerforum.co.za/forum/121-home-automation/

Edit: You will be able to see all the data from your inverter and batteries such as PV generation, voltages, battery SOC etc.

 

 

Edited by francois
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Have just done something similar with RCT-Axpert with same limitation as Kodak MKII

Real live experience

12 x Canadian 410 in strings of 2 (wanted to stay safe) - beware they are big

Producing 3.17Kw at 12:30pm and up to 4Kw later in the day (good clear day). As we are on prepaid, I installed a manual change-over switch to ensure that I can access utility power when we have a bad day. Obviously it is one or the other.

As to the geyser, we have installed a Geyser Wise and replaced the element with a 2Kw unit - you need to have a smaller element! 

Also looking at home automation, so thanks to @francois for the links

 

 

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6 minutes ago, wimsza said:

Have just done something similar with RCT-Axpert with same limitation as Kodak MKII

Real live experience

12 x Canadian 410 in strings of 2 (wanted to stay safe) - beware they are big

Producing 3.17Kw at 12:30pm and up to 4Kw later in the day (good clear day). As we are on prepaid, I installed a manual change-over switch to ensure that I can access utility power when we have a bad day. Obviously it is one or the other.

As to the geyser, we have installed a Geyser Wise and replaced the element with a 2Kw unit - you need to have a smaller element! 

Also looking at home automation, so thanks to @francois for the links

 

 

 

With 12 x 410 panels, you're exceeding the inverters max limit of 4500. Are you not worried what happens when you get peak power - like cold days etc? 

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The max limit on mine is 5000, however each string is on a Noark breaker which means I can switch one off if need be.

Also make sure your budget includes all those extras such as breakers, cable, change over switch, surge protectors etc - it all adds up. Oh, and don't forget the cost of the mounting system - shop around as it varies quite a bit

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3 minutes ago, wimsza said:

The max limit on mine is 5000, however each string is on a Noark breaker which means I can switch one off if need be.

Also make sure your budget includes all those extras such as breakers, cable, change over switch, surge protectors etc - it all adds up. Oh, and don't forget the cost of the mounting system - shop around as it varies quite a bit

I think the PV is 4500w, the inverter is 5000w. But yeah, anyway if its working, its working. :) 

How much energy are you producing during your average days? (I mean total for the day) 

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