Help, new build

[Wahki]

Hi guys, I'm completely new to solar but I've been looking at it for quite some time. Well the time has come for me to actually get into it because we are now completely off-grid!!! I am not an electrician or knowledgeable about these things in any way, so I need quite a bit of help and advice...

Firstly, my family and I live in South Africa in a part of the country where we are blessed with abundant sunshine! According to GIS data (https://solargis.com/maps-and-gis-data/) where we live gets on average 5-6 hours of sun per day, and I can tell that is right through the year even in winter it is about 4-5 hours of full sun (semi-desert). Secondly, we are now forced to go solar because the cost to connect to the grid is roughly (and here I'm talking only to bring power to the house, no installation) $1600.00 US, so solar makes sense.

On average we consumed (while on grid) 6kW/h per day, and that ran the following:
Fridge/freezer 730w per day (24hrs)
Computer and monitor 468w (10hrs per day)
LED TV + set-top box 80w (6-8hrs per day, these measurements were done during lockdown in South Africa, one of the longest and hardest lockdowns in the world)
WiFi router (not sure of it's consumption, but it ran 24hrs)
7x9w LED lights (average about 7hrs, at night and early morning)
Cellphone charging: 3x5w (average 3hrs, like I said lockdown figures, oh and kids are homeschooled...)
Tablets: 2x10w (2hrs)
Washing machine 730w (run for 3hrs only on a weekend, this additional usage also added up to our average daily use)
Clothes iron 1600w (20min)
Microwave: 900w (30min)

What we are looking at now, to start with, is running lights and power for charging phones and tablets. For the lights I'm looking at running LED strips, 2x400mm strips per room, which I've calculated would use about 89.6w (6.4m @ 14w/m) and this would run off 12-way fuse block. The idea is to use 2 of these solar panels which are locally manufactured, together with the Tracer 6420AN and the Vision Revo SP 12-200, 200Ah LiFePo4 battery. (data sheets/user manuals attached)

We plan to grow the system later on, expanding it to a 24v system and adding an inverter to run some AC appliances. Do you think the above setup would work, and what advice do you have regarding putting it all together (wire sizes, fuses, circuit breakers, etc)?

 

[Frank in Thailand]

Congratulations on your new home!

As I assume you just moved to rural environment.

The old energy usage of just 6kwh per 24h is really low for refrigerator and all the rest!!
You must have had a cool apartment.

In Thailand, with same amount of sun, out temperatures are quickly 35-45C, with matching energy consumption for the refrigerator.

Airconditioning will reduce the power consumption from the refrigerator, but eat its own portion

Our new energy efficient 180cm high refrigerator with freezer use about 3.5-4.5kwh per day.
That's without the airconditioning running in the living room/kitchen.
With airconditioning it's 2-3kwh per day. We don't cool our rooms to 20c
25-28c is good when it's outside 40

Anyways, this doesn't help you much.
We live off grid and have normal western energy consumption.

To be able to provide this, we needed a lot (!!!) Of solar panels and battery, + inverters.

We started with 2 X 300w panels that was enough for lights and small usage, with 2 X 135Ah lead acid.

We had one large challenge..
My wife purchased a 2000W deep well pump.
So our inverter needed to be able to power that beast.
A 2000w inverter, even with advertised peak of 5000w.. won't work. We know now from experience.

Sister in law bought refrigerator and didn't tell us about it...
That was 2 days and the healthy system was struggling, dead before 21 in the evening.

Lesson learned: lead acid sucks.
135Ah isn't 135Ah.
You can use 40-60% max, and with higher temperatures, it's more 30-45%
Besides this, from each 100W produced by solar, just 85W is stored in the lead acid battery (+95w with LiFePO4)
And, using this power will give an other 10-15% loss.
The 100 watt solar is 70-75w usable.

Then there is the weather.
It's not always sunny!
We have rain season.
A refrigerator "needs" to operate 24/7, for long-living for the food and refrigerator itself.

For us on a rainy day the panels make about 0-50 watt
That means a load of panels, and battery storage.

Usually it's short period of time without sun, a few days.
In Netherlands, Europe, we have weeks gray slow rain, low lights.
Lucky not here

We started with 24v 2000w inverter, Mppt, 2*300w solar and 2 * 135Ah lead acid.
We now have:
27*325W and 16*345w Solar.
3 * hybrid 3.2kw Inverter (max 5kw mppt)
+50Kwh LiFePO4 cells

That was a development path in about 2.5 years and spend way more then $16.000

We live 8Km from the grid, and the grid isn't stable to start with.

The 27+16 solar panels seem Overkill , but sadly isn't.

With 27 X 325 we had many days struggling with energy, using just one 8500BTU airconditioning in really good insulated room, refrigerator, lights and water pumps.
(Our water heater is LPG)
Deep well pump takes the water in the 1500L tank, RO pump for the filtration of drink water and normal pump for garden irrigation.
Usage of this pump automatically flushes the pre-filters of the RO system.
The RO filtration goes into 350l tank, who have its own pump for water pressure in the house.

Vulcanic Clay soil...
That does give several challenges before it can be used.

This was with 16* 200Ah deep cycle lead acid battery. Yes 800Ah@48v

I do need to add that (new but defective) EASun hybrid inverter charged the cells with 78v...
That took a few weeks before it was fried.

During rain season, the 27* 325 panels weren't enough to provide us with enough power.

From the 27, 18 are faced to the sun, not optimal angle for here, bit get real good production.
9 are faced to the evening sun.
That was a "mistake".
It's absolutely helps for extending the period the batteries are charged / solar energy is made, it doesn't give optimal power, ever.
About 200-250 when the others give +300.

To get it over with, we installed 16 panels extra on the greenhouse.

How does this help you?
Don't calculate with watts the way you are doing now.

Realise that optimal isn't realistic and even with 5-6 solar hours a day...
You don't have it.
Things like dust will reduce your production.
Things like conversion losses will bite you in the ass.

A 300 watt panel that have average 5-6 sun hours will realistic produce not 1500 watt, absolutely not 1800.
If you calculate 1000 watt, you can always say " hey, it's giving a bit more then expected"

For lead acid battery, you can use 40% of rated capacity, and you will lose 15% minimal, if they're nice warm... Even more.
From the 1.5/1.8kw you hoped form one 300w panel is now 850watt left over to use.
As DC.
Going to AC, loss again.
Make it 750 watt or 0.75kwh realistic available AC power from a whole day sun with one 300w panel.

Now I know these numbers are conservative, but realistic.

With a bit of luck you do get 1 kWh from the 300W panel.

Not directly after installation, but 3 months after...
As you probably won't clean the panels each day.
You will have more drain in your system that you expected, phone chargers, rice cooker, etc.

I'm trying to help you not to make the same mistakes I did.

Don't even talk about 12v and higher power things like refrigerator and washing machine.

Both need pure sine wave inverter.
Modified sine wave will damage the motors in both, first the refrigerator.

An inverter will always use power when its turned on.
My Chinese Sorotec Revo II 3.2kw use +/- 50 watt.
The Victron 3.2kw uses about 40w

That's own power consumption, always 24/7.
1.2kwh a day.
Don't trust the nice papers about crazy low standby power of 5w.
The inverter isn't providing energy then, aka, turned off.

Realistic. That's what I try to help you with.

If you are planning to use anything above 2000 watt, please go to 48v.
(Or for LiFePO4 51.2v)
The thickness of the cables, fuses, breakers, etc.
They are all half of 24v system, 1/4 from 12v.
2000w is 200A on 12v.
100A on 24, 50A on 48v.
(2000 watt :0.85 = 2350w drain on the battery)

The cheapest breakers aren't safe.
I've used them, and they worked fine for months. Till they don't, and melt, smoke and probably would have bursted out in flames if I did not pulled out the cable with force.

DC isn't AC, and a contact will make a spark, that's why those breakers are way more heavy (and more expensive) as they have an arc catcher.

You can easily weld with 100A.
200A you can cut 5 cm thick iron beam with the arc.

Please be careful when playing with higher amperage.

When I saw your calculations... Memories..
3 years ago I was same naïve.

If you don't mind living regularly without energy, no light, buy ice cubes at the local store to help the refrigerator, and wash by hand on regular basis, your calculations are OK and budget friendly.

My family in law doesn't care, they are living like that for ages.
3 X 100 watt solar, 1 * 12v battery and 250w inverter, enough for everyone and everything.

The whole family watching TV, and no one is using energy for something else.
Between 20-22 the lights go out.
With a new battery longer, but after 2-3 months it's the same.
So they only bought new when the lights stop before 20.00.

Things like washing machine and refrigerator.... Not.
Water from the gasoline pump.
Heating on charcoal and sometimes LPG.

They are rich in happiness and freedom, poor for money.

For them, having a refrigerator is absolutely luxury.
For me normal.

But it does cost.
More then you first expect.
If I seem my calculations now, they are still spot on, just not realistic.
They are about 1/3th of what's really needed.

I hope this helps you!
If you are in a windy area, you might consider wind turbine to assist.
They don't need to produce all the energy In a few hours, but can have the whole 24 hours to do so
Wind turbine does need some different equipment then solar, but can be a good combination

 

[Wahki]

Congratulations on your new home!

As I assume you just moved to rural environment.

The old energy usage of just 6kwh per 24h is really low for refrigerator and all the rest!!
You must have had a cool apartment.

In Thailand, with same amount of sun, out temperatures are quickly 35-45C, with matching energy consumption for the refrigerator.

Airconditioning will reduce the power consumption from the refrigerator, but eat its own portion

Our new energy efficient 180cm high refrigerator with freezer use about 3.5-4.5kwh per day.
That's without the airconditioning running in the living room/kitchen.
With airconditioning it's 2-3kwh per day. We don't cool our rooms to 20c
25-28c is good when it's outside 40

Anyways, this doesn't help you much.
We live off grid and have normal western energy consumption.

To be able to provide this, we needed a lot (!!!) Of solar panels and battery, + inverters.

We started with 2 X 300w panels that was enough for lights and small usage, with 2 X 135Ah lead acid.

We had one large challenge..
My wife purchased a 2000W deep well pump.
So our inverter needed to be able to power that beast.
A 2000w inverter, even with advertised peak of 5000w.. won't work. We know now from experience.

Sister in law bought refrigerator and didn't tell us about it...
That was 2 days and the healthy system was struggling, dead before 21 in the evening.

Lesson learned: lead acid sucks.
135Ah isn't 135Ah.
You can use 40-60% max, and with higher temperatures, it's more 30-45%
Besides this, from each 100W produced by solar, just 85W is stored in the lead acid battery (+95w with LiFePO4)
And, using this power will give an other 10-15% loss.
The 100 watt solar is 70-75w usable.

Then there is the weather.
It's not always sunny!
We have rain season.
A refrigerator "needs" to operate 24/7, for long-living for the food and refrigerator itself.

For us on a rainy day the panels make about 0-50 watt
That means a load of panels, and battery storage.

Usually it's short period of time without sun, a few days.
In Netherlands, Europe, we have weeks gray slow rain, low lights.
Lucky not here

We started with 24v 2000w inverter, Mppt, 2*300w solar and 2 * 135Ah lead acid.
We now have:
27*325W and 16*345w Solar.
3 * hybrid 3.2kw Inverter (max 5kw mppt)
+50Kwh LiFePO4 cells

That was a development path in about 2.5 years and spend way more then $16.000

We live 8Km from the grid, and the grid isn't stable to start with.

The 27+16 solar panels seem Overkill , but sadly isn't.

With 27 X 325 we had many days struggling with energy, using just one 8500BTU airconditioning in really good insulated room, refrigerator, lights and water pumps.
(Our water heater is LPG)
Deep well pump takes the water in the 1500L tank, RO pump for the filtration of drink water and normal pump for garden irrigation.
Usage of this pump automatically flushes the pre-filters of the RO system.
The RO filtration goes into 350l tank, who have its own pump for water pressure in the house.

Vulcanic Clay soil...
That does give several challenges before it can be used.

This was with 16* 200Ah deep cycle lead acid battery. Yes 800Ah@48v

I do need to add that (new but defective) EASun hybrid inverter charged the cells with 78v...
That took a few weeks before it was fried.

During rain season, the 27* 325 panels weren't enough to provide us with enough power.

From the 27, 18 are faced to the sun, not optimal angle for here, bit get real good production.
9 are faced to the evening sun.
That was a "mistake".
It's absolutely helps for extending the period the batteries are charged / solar energy is made, it doesn't give optimal power, ever.
About 200-250 when the others give +300.

To get it over with, we installed 16 panels extra on the greenhouse.

How does this help you?
Don't calculate with watts the way you are doing now.

Realise that optimal isn't realistic and even with 5-6 solar hours a day...
You don't have it.
Things like dust will reduce your production.
Things like conversion losses will bite you in the ass.

A 300 watt panel that have average 5-6 sun hours will realistic produce not 1500 watt, absolutely not 1800.
If you calculate 1000 watt, you can always say " hey, it's giving a bit more then expected"

For lead acid battery, you can use 40% of rated capacity, and you will lose 15% minimal, if they're nice warm... Even more.
From the 1.5/1.8kw you hoped form one 300w panel is now 850watt left over to use.
As DC.
Going to AC, loss again.
Make it 750 watt or 0.75kwh realistic available AC power from a whole day sun with one 300w panel.

Now I know these numbers are conservative, but realistic.

With a bit of luck you do get 1 kWh from the 300W panel.

Not directly after installation, but 3 months after...
As you probably won't clean the panels each day.
You will have more drain in your system that you expected, phone chargers, rice cooker, etc.

I'm trying to help you not to make the same mistakes I did.

Don't even talk about 12v and higher power things like refrigerator and washing machine.

Both need pure sine wave inverter.
Modified sine wave will damage the motors in both, first the refrigerator.

An inverter will always use power when its turned on.
My Chinese Sorotec Revo II 3.2kw use +/- 50 watt.
The Victron 3.2kw uses about 40w

That's own power consumption, always 24/7.
1.2kwh a day.
Don't trust the nice papers about crazy low standby power of 5w.
The inverter isn't providing energy then, aka, turned off.

Realistic. That's what I try to help you with.

If you are planning to use anything above 2000 watt, please go to 48v.
(Or for LiFePO4 51.2v)
The thickness of the cables, fuses, breakers, etc.
They are all half of 24v system, 1/4 from 12v.
2000w is 200A on 12v.
100A on 24, 50A on 48v.
(2000 watt :0.85 = 2350w drain on the battery)

The cheapest breakers aren't safe.
I've used them, and they worked fine for months. Till they don't, and melt, smoke and probably would have bursted out in flames if I did not pulled out the cable with force.

DC isn't AC, and a contact will make a spark, that's why those breakers are way more heavy (and more expensive) as they have an arc catcher.

You can easily weld with 100A.
200A you can cut 5 cm thick iron beam with the arc.

Please be careful when playing with higher amperage.

When I saw your calculations... Memories..
3 years ago I was same naïve.

If you don't mind living regularly without energy, no light, buy ice cubes at the local store to help the refrigerator, and wash by hand on regular basis, your calculations are OK and budget friendly.

My family in law doesn't care, they are living like that for ages.
3 X 100 watt solar, 1 * 12v battery and 250w inverter, enough for everyone and everything.

The whole family watching TV, and no one is using energy for something else.
Between 20-22 the lights go out.
With a new battery longer, but after 2-3 months it's the same.
So they only bought new when the lights stop before 20.00.

Things like washing machine and refrigerator.... Not.
Water from the gasoline pump.
Heating on charcoal and sometimes LPG.

They are rich in happiness and freedom, poor for money.

For them, having a refrigerator is absolutely luxury.
For me normal.

But it does cost.
More then you first expect.
If I seem my calculations now, they are still spot on, just not realistic.
They are about 1/3th of what's really needed.

I hope this helps you!
If you are in a windy area, you might consider wind turbine to assist.
They don't need to produce all the energy In a few hours, but can have the whole 24 hours to do so
Wind turbine does need some different equipment then solar, but can be a good combination

Fhorst, I can't thank you enough!!!

You have given me lots to think about, and I'm glad that you have also included some of your own experience with solar.

I'm well aware that we'll need to further upgrade the system, as you mentioned 48v is best, but at the moment finances are quite tight so we're looking at our immediate needs for now. ?We have been without our refrigerator for 3 months now and have learnt to adjust our purchases accordingly, we therefore have no immediate need to have it connected. I think we have indirectly been utilising geothermal principals for keeping things cool: in our place we have a concrete floor (mixed with sand and coal ash from a local cheese factory), and we have used this to keep drinks and food cool (obviously not for more than 3 days) and nothing has gone bad, granted our temperatures are not at summer highs of 35°C+.

We are definitely going the LiFePo4 route as these would give us longer lifespan and also handle the heat a bit better. We have started with properly insulating our place and making use of natural cooling and heating in order to provide a more even temperature indoors, as well as a more consistent temperature for the solar equipment.

I will be posting some rough diagrams soon.