Hi, I'm looking for advice on solar backups. I'd like to be prepped for a worst-case scenario when the power goes out for more than a day. As an advantage, if it reduces my bill, then great! I need to power the following:

1 gaming PC, my work laptop, a fan, a fridge/freezer. Ideally, it would be a grid-tied system, so I guess that means solar in the day and Eskom at night? 

I can't seem to find a decent and affordable supplier and installer in Durban. I'm being quoted for complete systems costing over R150 000. This is not what I want or need. 

How much, on average, would I need to spend for the above requirements? Any suggestions on a good installer in Durban who won't require me to sell my kidney? 

Any assistance would be appreciated. 

Edited February 13, 20233 yr by SG001

Let's say that a grid-tied system is one that supplements your grid feed with power from PV panels. There is no storage, just supplementing. You've already said "solar in the day and Eskom at night", so I think we are talking about the same thing.

Such a system will reduce your bill, but won't give you protection against load shedding. 

For protection against load shedding you need a store of energy you can fall back on. In a home this is batteries. So the talk now switches to how you charge those batteries, how much battery you need, and your budget. 

Your loads don't sound high, but you should try to quantify them so that you can calculate how much stored energy you need for a 2 hour outage, a 4 hour outage, > 4 hours. 

Make sure you include EVERYTHING you need backed up. Presumably you have a wifi device and/or a fibre interface that needs to be backed up. Include it all, add it all up.

You should get a system with a pure sine wave output since you are going to be powering motors. Modified sine wave systems are not recommended when you want to power motors.

You're probably going to need to split the DB so that there are backed up and non-backed up circuits. This is common. Without this the geyser will turn on, the oven will come into use, and your battery will discharge very quickly. Or something is left plugged in and again you are backing up more than anticipated.

So you need an inverter and batteries. That won't save you money on your electricity bill since you are still going to be using the same amount of electricity (maybe a little more, but not a huge amount), but it will give you back up power at any time of day. You can add PV later.  PV is what saves money.

Prices... well, try to figure out what the load you need to back up is (see above). There are two ways of looking at this. The average, constant load, and the peak load which will occur when devices start up (EG the motor in your fridge). The first gives an idea of how much battery you need, the second gives the upper limit of the current the inverter needs to supply.

I'd suggest buying more than you think you'll need if you can afford it. Loadshedding is going to be with us for some time, and it is very nice to have lights on, to be able to make a cup of coffee and so on.

 

6 hours ago, Bobster. said:

Let's say that a grid-tied system is one that supplements your grid feed with power from PV panels. There is no storage, just supplementing. You've already said "solar in the day and Eskom at night", so I think we are talking about the same thing.

Such a system will reduce your bill, but won't give you protection against load shedding. 

For protection against load shedding you need a store of energy you can fall back on. In a home this is batteries. So the talk now switches to how you charge those batteries, how much battery you need, and your budget. 

Your loads don't sound high, but you should try to quantify them so that you can calculate how much stored energy you need for a 2 hour outage, a 4 hour outage, > 4 hours. 

Make sure you include EVERYTHING you need backed up. Presumably you have a wifi device and/or a fibre interface that needs to be backed up. Include it all, add it all up.

You should get a system with a pure sine wave output since you are going to be powering motors. Modified sine wave systems are not recommended when you want to power motors.

You're probably going to need to split the DB so that there are backed up and non-backed up circuits. This is common. Without this the geyser will turn on, the oven will come into use, and your battery will discharge very quickly. Or something is left plugged in and again you are backing up more than anticipated.

So you need an inverter and batteries. That won't save you money on your electricity bill since you are still going to be using the same amount of electricity (maybe a little more, but not a huge amount), but it will give you back up power at any time of day. You can add PV later.  PV is what saves money.

Prices... well, try to figure out what the load you need to back up is (see above). There are two ways of looking at this. The average, constant load, and the peak load which will occur when devices start up (EG the motor in your fridge). The first gives an idea of how much battery you need, the second gives the upper limit of the current the inverter needs to supply.

I'd suggest buying more than you think you'll need if you can afford it. Loadshedding is going to be with us for some time, and it is very nice to have lights on, to be able to make a cup of coffee and so on.

 

Thank you. This is very helpful! It's given me a good understanding of what I need. I really appreciate the response and the detail.

It seems to me like the 5 to 8 kva systems I've been getting quoted on is completely unnecessary. I definitely do want something that will give me more than 4 hours of back up. 

The next question is, where do I find a reliable supplier and installer who can give me a decent quote in Durban?

Edited February 13, 20233 yr by SG001

@Steve87 will be in durban over the next couple weeks... contact him