I have a one-bedroom flat attached to my house that I occasionally rent out short-term. We’re fully on solar, which powers both the house and flat well in summer, but in winter we struggle, because both use electric geysers. The main house has a gas stove, but the flat’s electric stove makes it worse when guests cook often. I’m considering renting the flat out longer term and investing about R16,000 to move it partly off the home system. This will mean replacing the geyser and two-burner stove with gas options. I’d provide one 19kg gas bottle at move-in, after which the tenant refills it. My concern is power misuse: a past guest installed their own electric geyser, overloading the system. Is there a way to prevent this? Perhaps a device that limits plug power draw to under 1000W?

44 minutes ago, Kory said:

I have a one-bedroom flat attached to my house that I occasionally rent out short-term. We’re fully on solar, which powers both the house and flat well in summer, but in winter we struggle, because both use electric geysers. The main house has a gas stove, but the flat’s electric stove makes it worse when guests cook often. I’m considering renting the flat out longer term and investing about R16,000 to move it partly off the home system. This will mean replacing the geyser and two-burner stove with gas options. I’d provide one 19kg gas bottle at move-in, after which the tenant refills it. My concern is power misuse: a past guest installed their own electric geyser, overloading the system. Is there a way to prevent this? Perhaps a device that limits plug power draw to under 1000W?

You can control the plugs by putting in small circuit breakers. But beware of unintended consequences. An electric kettle, an iron, a microwave may well draw more than 1kW, and I doubt you want to rule out the use of those.

If the gas water heating provides hot water on demand, then there's no need for a tenant to go to such lengths.

Speak to B&B owners. They will know the ways to heat water efficiently and cheaply.

Also put in a water saving shower head. If water can't be drawn from the geyser as quickly, the geyser doesn't need as much reheating. These need not reduce a shower to a trickle. I have flow restricting heads fitted, and they actually give a nice shower with multiple jets.

2 hours ago, Bobster. said:

You can control the plugs by putting in small circuit breakers. But beware of unintended consequences. An electric kettle, an iron, a microwave may well draw more than 1kW, and I doubt you want to rule out the use of those.

If the gas water heating provides hot water on demand, then there's no need for a tenant to go to such lengths.

Speak to B&B owners. They will know the ways to heat water efficiently and cheaply.

Also put in a water saving shower head. If water can't be drawn from the geyser as quickly, the geyser doesn't need as much reheating. These need not reduce a shower to a trickle. I have flow restricting heads fitted, and they actually give a nice shower with multiple jets.

Yes so microwave and kettle are in the kitchen area and the kitchen area plugs are on one breaker. The microwave is permanently plugged in and well the kettle it will just not make sense to move it. Plus I choose 1000w because I made sure all the kettles in the house do not draw more than a 1000w due to going solar. The question is will the use of anything that draws more than required trip the entire house power or just the power for the flat, it is on a sub db or alternatively it will just not work.

55 minutes ago, Kory said:

Yes so microwave and kettle are in the kitchen area and the kitchen area plugs are on one breaker. The microwave is permanently plugged in and well the kettle it will just not make sense to move it. Plus I choose 1000w because I made sure all the kettles in the house do not draw more than a 1000w due to going solar. The question is will the use of anything that draws more than required trip the entire house power or just the power for the flat, it is on a sub db or alternatively it will just not work.

I think the best you can do is fit the gas appliances, and get an electrician to check what is on the sub DB* and put protection in place with circuit breakers. What did this other tenant use to power that geyser?

There are still problems: If the kettle and the microwave are in use at the same time then is that more than 1kW? That's not an unreasonable thing to do, but it may cause a trip.

You would need to be upfront with any incoming tenant so that they know what they can do that doesn't leave them in darkness.

* my property has two geysers, both in the main house. There is a sub-DB in the outbuildings. But the outbuildings get hot water from one of the geysers in the main house, and the breaker for the 2nd geyser (a later addition) is in the sub-DB. IDK. It was like that when I moved in. But if you're not sure then get it checked, or test for yourself when you have time by switching breakers off and seeing what stops working.

The sub-DB has a breaker on the main DB which places a limit on total draw for the outbuildings (and that other geyser that isn't in the outbuildings but has an electrical connection to them).

Edited November 6, 2025Nov 6 by Bobster.
clarity

Alternatively, put the flat on it's own solar, with a pre-paid meter between it and the main house. You could put big drawing items on non-backed up side of the inverter. They will likely draw some power from the grid - which is where the pre-paid meter comes in. Tell the tenant the solar only backs up lights, some plugs and it's up to them to not overload the system and to feed the pre-paid meter.

41 minutes ago, Bobster. said:

Alternatively, put the flat on it's own solar, with a pre-paid meter between it and the main house. You could put big drawing items on non-backed up side of the inverter. They will likely draw some power from the grid - which is where the pre-paid meter comes in. Tell the tenant the solar only backs up lights, some plugs and it's up to them to not overload the system and to feed the pre-paid meter.

Do ISPs do private prepaid meters that are not part of a utility connection?

Thinking of how the payment gets to the tenant credit on the meter.

I would get a whistle kettle and induction plate and train the tenant to use it on lower power or get the 1.2kW induction plate. This is a lot better than them using a 2.2kW kettle. I boil mine on the 1kW setting.

1 hour ago, Scorp007 said:

Do ISPs do private prepaid meters that are not part of a utility connection?

Thinking of how the payment gets to the tenant credit on the meter.

I should have called it a sub-meter. There are companies that do this. The sub-meter sits between the municipal meter and the rented property. It meters what the rented property consumes. You can run it just in monitoring mode (my sister has one in her home, installed by the previous owner) or you can set it so that the tenant has to load tokens or run out of juice.

See https://www.recharger.co.za/pages/getting-started as an example.

1 hour ago, Scorp007 said:

I would get a whistle kettle and induction plate and train the tenant to use it on lower power or get the 1.2kW induction plate. This is a lot better than them using a 2.2kW kettle. I boil mine on the 1kW setting.

I still a good old whistle kettle that we used to use during load sheddding (before we had solar). But you're assuming the tenant is a reasonable person. And most will be, but see the note above about the tenant who installed his own geyser element and overloaded the PV system.

2 minutes ago, Bobster. said:

I should have called it a sub-meter. There are companies that do this. The sub-meter sits between the municipal meter and the rented property. It meters what the rented property consumes. You can run it just in monitoring mode (my sister has one in her home, installed by the previous owner) or you can set it so that the tenant has to load tokens or run out of juice.

You can buy the meters cheap! At Builders and such places. R89 for a Hexing. I'm hoping this is a once-off loss the vendor takes because he knows he's going to make money selling tokens. Or something.

1 hour ago, Bobster. said:

You can buy the meters cheap! At Builders and such places. R89 for a Hexing. I'm hoping this is a once-off loss the vendor takes because he knows he's going to make money selling tokens. Or something.

How is the token value added to the meter?

This means you will be selling power to the tenant and that is against the law AFAIK.

11 hours ago, Scorp007 said:

How is the token value added to the meter?

This means you will be selling power to the tenant and that is against the law AFAIK.

I must say I was wondering about that too. They do discuss pricing in their FAQ.

But there they are, operating openly.

Edited November 7, 2025Nov 7 by Bobster.
I've been reading a book about punctuation, so I punctuated in the interest of clarity

22 hours ago, Bobster. said:

I think the best you can do is fit the gas appliances, and get an electrician to check what is on the sub DB* and put protection in place with circuit breakers. What did this other tenant use to power that geyser?

There are still problems: If the kettle and the microwave are in use at the same time then is that more than 1kW? That's not an unreasonable thing to do, but it may cause a trip.

You would need to be upfront with any incoming tenant so that they know what they can do that doesn't leave them in darkness.

* my property has two geysers, both in the main house. There is a sub-DB in the outbuildings. But the outbuildings get hot water from one of the geysers in the main house, and the breaker for the 2nd geyser (a later addition) is in the sub-DB. IDK. It was like that when I moved in. But if you're not sure then get it checked, or test for yourself when you have time by switching breakers off and seeing what stops working.

The sub-DB has a breaker on the main DB which places a limit on total draw for the outbuildings (and that other geyser that isn't in the outbuildings but has an electrical connection to them).

Well if I manage to fit the gas appliances the electric use will minimized so I will not stress too much. The Setup is as follows: There are two electric geyser; one for the main house and the second for the flat. I am not worried about sumner as we barely buy electric with solar. The flat has a sub DB which shares it circuits with the garages. I think garages plugs are on one, garage light on the other, then kitchenette plugs on one the geyser on one, all other plugs one one but all the light are together. The sub db then has a breaker on the main db. I am able to switch off the flat DB if I turn the breaker off in the main house. My issue is not to prevent them from consuming but as much as possible to ensure they pay for their consumption without me needing to intervene. I do not rent consistently and generally most tenants have been easy as I rent to single persons of occasionally a couple. But I have had a few hard nuts.

Just now, Kory said:

But I have had a few hard nuts.

As you described earlier. But you will have to cater for the worst case that you can foresee.

22 hours ago, Scorp007 said:

Do ISPs do private prepaid meters that are not part of a utility connection?

Thinking of how the payment gets to the tenant credit on the meter.

I would get a whistle kettle and induction plate and train the tenant to use it on lower power or get the 1.2kW induction plate. This is a lot better than them using a 2.2kW kettle. I boil mine on the 1kW setting.

It is actually a 2 burner induction plate that is in the flat. Getting the flat on an independent solar system might be a waste as current setup means when the flat is not in use the main house can use the excess production. I think based on the feedback, thanks so much everyone. The best option is to do the gas switch to move the two main sources of power draw off my back. It will also be helpful in preserving my battery as the main house uses gas and but the flat cooks with electric and so cooking late and early draws from my batteries.