Small backup/semi off grid office setup

[Terence1983]

Ok so lately in my area we have been 'routine' maintenance and the power goes off for almost the entire day and this is getting more and more frequent. I work from home on a permanent basis so I need to be online 100% of the time from 6am to 5pm. I basically need to run a laptop, with 2nd screen and fibre router, I doubt all of this will even pull 200-300 watts. So im been looking for a small and as cheap as possible solar solution. Generator would cost the same as what ive seen for a small diy solar setup but then maintenance and running costs will start adding up over time. So my plan is a small inverter, max 1kw but even that may be overkill, 1 or 2 100ah batteries, 30amp solar charge controller and either 1 or 2 solar panels, around 200w to 400w max which everything should run off with the batteries as back up.

I have found a complete DIY set up for R4995 which includes:
1000w inverter
100ah gel battery
200w mono solar panel
30amp charge controller
cabling

I can always add more solar panels and batteries as I go along.

I can probably source individual items for a bit less if I shop around. My dad has a small goldstone 660w inverter which he runs his flat screen and dstv decoder off a small normal lead acid car battery and it lasts 3-4 hours so im thinking something like that inverter which costs around R800 could suit my needs just fine.

Am I crazy or could be a viable option?

 

[TheChamp]

Ok so lately in my area we have been 'routine' maintenance and the power goes off for almost the entire day and this is getting more and more frequent. I work from home on a permanent basis so I need to be online 100% of the time from 6am to 5pm. I basically need to run a laptop, with 2nd screen and fibre router, I doubt all of this will even pull 200-300 watts. So im been looking for a small and as cheap as possible solar solution. Generator would cost the same as what ive seen for a small diy solar setup but then maintenance and running costs will start adding up over time. So my plan is a small inverter, max 1kw but even that may be overkill, 1 or 2 100ah batteries, 30amp solar charge controller and either 1 or 2 solar panels, around 200w to 400w max which everything should run off with the batteries as back up.

I have found a complete DIY set up for R4995 which includes:
1000w inverter
100ah gel battery
200w mono solar panel
30amp charge controller
cabling

I can always add more solar panels and batteries as I go along.

I can probably source individual items for a bit less if I shop around. My dad has a small goldstone 660w inverter which he runs his flat screen and dstv decoder off a small normal lead acid car battery and it lasts 3-4 hours so im thinking something like that inverter which costs around R800 could suit my needs just fine.

Am I crazy or could be a viable option?

Link to the DIY kit?

 

[wingnut771]

Ok so lately in my area we have been 'routine' maintenance and the power goes off for almost the entire day and this is getting more and more frequent. I work from home on a permanent basis so I need to be online 100% of the time from 6am to 5pm. I basically need to run a laptop, with 2nd screen and fibre router, I doubt all of this will even pull 200-300 watts. So im been looking for a small and as cheap as possible solar solution. Generator would cost the same as what ive seen for a small diy solar setup but then maintenance and running costs will start adding up over time. So my plan is a small inverter, max 1kw but even that may be overkill, 1 or 2 100ah batteries, 30amp solar charge controller and either 1 or 2 solar panels, around 200w to 400w max which everything should run off with the batteries as back up.

I have found a complete DIY set up for R4995 which includes:
1000w inverter
100ah gel battery
200w mono solar panel
30amp charge controller
cabling

I can always add more solar panels and batteries as I go along.

I can probably source individual items for a bit less if I shop around. My dad has a small goldstone 660w inverter which he runs his flat screen and dstv decoder off a small normal lead acid car battery and it lasts 3-4 hours so im thinking something like that inverter which costs around R800 could suit my needs just fine.

Am I crazy or could be a viable option?

Car batteries are not meant to be continuous discharged. That battery is going to be poked in no time. You need deep cycle batteries for continuous discharge and even then only to 50% depth of discharge or your cycle life suffer:

 

[RedViking]

Maybe a Mecer 2400VA, 2/4x105ah DEEP CYCLE batteries and the solar charger. This should get you through the day and continue to charge at night if power is on.

Mecer 2400VA Inverter (Community Support)

This Thread is for the Mecer Inverter only. My personal opinion on the unit: Seeing that there are lots of question and in lots if threads, here is my review/input on the Mecer Inverter. Instead of reposting I'll just reference here. I'll add more info soon. This should give you an idea what...

mybroadband.co.za

I have not been without power since I got mine. Although I haven't had to use it for longer than 4 hours, so don't have a solar charger yet.

 

[RedViking]

12V
https://www.geewiz.co.za/long-run-u...5ah-battery-8-hour-battery-life-kit-720w.html

Or

24V
https://www.geewiz.co.za/long-run-u...ah-battery-8-hour-battery-life-kit-1440w.html

Deep Cycle Batteries 105AH:
https://www.geewiz.co.za/batteries/...-volt.html?search_query=deep+cycle&results=33

Solar Charger Controller (confirm with GeeWiz if it is the correct one):
https://www.geewiz.co.za/chargers/2...ks.html?search_query=solar+charger&results=25

Digital Watt Meter (to measure Wattage):
https://www.geewiz.co.za/gadgets/43...usage.html?search_query=watt+

Q) I would like to add more than 2 batteries, how must I connect them?
Please ask in the Battery Thread and see question above.

) Can I run my TV, Computer, 600W Cat, 2000W Dog & Fridge? For how long?
See Post#2 above for rough calculations.

I also tried to explain better in here.

@COMPUTEK made a very nice excel spreadsheet here.

 

[Terence1983]

Link to the DIY kit?

Don't have a link to it, I saw it on facebook marketplace while browsing

 

[Terence1983]

Car batteries are not meant to be continuous discharged. That battery is going to be poked in no time. You need deep cycle batteries for continuous discharge and even then only to 50% depth of discharge or your cycle life suffer:
View attachment 1022946

Yes I will be getting deep cycle batteries, I just used my dads setup as an example for the type of inverter im looking at

 

[Terence1983]

Maybe a Mecer 2400VA, 2/4x105ah DEEP CYCLE batteries and the solar charger. This should get you through the day and continue to charge at night if power is on.

Mecer 2400VA Inverter (Community Support)

This Thread is for the Mecer Inverter only. My personal opinion on the unit: Seeing that there are lots of question and in lots if threads, here is my review/input on the Mecer Inverter. Instead of reposting I'll just reference here. I'll add more info soon. This should give you an idea what...

mybroadband.co.za

I have not been without power since I got mine. Although I haven't had to use it for longer than 4 hours, so don't have a solar charger yet.

I looked at this option but the mecer unit with 2 batteries is way over my initial budget, hence I want to try go smaller on the inverter and batteries and use solar as much as possible during the day. This is purely a back up for now with the view of taking the office off grid at later stage with bigger battery bank and more solar.

 

[TheChamp]

I looked at this option but the mecer unit with 2 batteries is way over my initial budget, hence I want to try go smaller on the inverter and batteries and use solar as much as possible during the day. This is purely a back up for now with the view of taking the office off grid at later stage with bigger battery bank and more solar.

It could work, just remember that a 12V system is very inefficient on solar, it draws much more current and you will find your solar falling short.

What budget were you hoping to stick to?

 

[Terence1983]

It could work, just remember that a 12V system is very inefficient on solar, it draws much more current and you will find your solar falling short.

What budget were you hoping to stick to?

Ok cool thanks for the heads up, I will look into a 24v system. my initial budget is around R6000 to start off with and il work from there, I wanted to go with 12v as it would require 1 battery to start off with and I could always buy a 2nd one in a month or 2.

 

[Lupus]

Ok cool thanks for the heads up, I will look into a 24v system. my initial budget is around R6000 to start off with and il work from there, I wanted to go with 12v as it would require 1 battery to start off with and I could always buy a 2nd one in a month or 2.

A second battery would need to be hooked up in series though, rather try stretch to the 24v system

 

[Napalm2880]

A second battery would need to be hooked up in series though, rather try stretch to the 24v system

Why is a 24v system better than a 12v system?

 

[wingnut771]

A second battery would need to be hooked up in series though, rather try stretch to the 24v system

Parallel don't you mean if he wanted to extend his 12V capacity?

 

[Terence1983]

Will continue doing my homework and researching but yea 24v does seem to be the better option.

 

[wingnut771]

AFAIK, the only reason to go 24V is the cabling is much cheaper as the current is less, but in this setup, I don't think it matters much if we only using 300W. 300 divide 12V = 25A. Install 600W solar and should be good for cloudy days imho.

 

[TheChamp]

Why is a 24v system better than a 12v system?

Current, at double the voltage current is halved, which make sense if you are using solar panels because they have more voltage than current.

 

[TheChamp]

AFAIK, the only reason to go 24V is the cabling is much cheaper as the current is less, but in this setup, I don't think it matters much if we only using 300W. 300 divide 12V = 25A.

If you are going to be depending on solar to prop you up it does make a difference, it's much easier to get 12.5A from solar than to get 25A.

 

[Terence1983]

If you are going to be depending on solar to prop you up it does make a difference, it's much easier to get 12.5A from solar than to get 25A.

This actually makes a lot of sense if im understanding correctly, ie 2x 200w 24v panels would work better than 2x200w 12v panels? Higher amperage would mean faster recharging of the batteries. Am I understanding this correctly?

 

[wingnut771]

If you are going to be depending on solar to prop you up it does make a difference, it's much easier to get 12.5A from solar than to get 25A.

Surely that is dictated by your correctly sized MPPT charger and panel makeup? So, still pretty easy to get 25A?

 

[wingnut771]

This actually makes a lot of sense if im understanding correctly, ie 2x 200w 24v panels would work better than 2x200w 12v panels? Higher amperage would mean faster recharging of the batteries. Am I understanding this correctly?

AFAIK, it's a combination of both. You need the voltage higher than the battery, but it's the amps that provide the oomph. So 12V needs a panel higher than 12V like a 150W 18V, and then you can parallel them to get the amps up.