Hello all

I'm working with my body corporate on a whole-block grid-tied PV system with battery backup. The idea is that the economies of scale of 41 flats will change the economics for us, and even more if we can team up with the neighbouring building of 68 flats.

Has anyone else been involved in something like this? We're looking for a power-purchase agreement setup from a specialist company. I'd be interested in hearing about other people's investigations/experiences/prices/etc.

I'd also be interested in any links to panel and battery calculators (or just excel models) that can cope with the numbers involved (12000-25000KWh depending on the month) since they all seem to cap out at amounts for single-dwelling mega-users.

Thanks!

J

Edited August 18, 20214 yr by jharber

Look into Micro grids, this is the reason for their existence. There may also be legal issues involved here. Only the owner of the system can consume the energy. You will likely not be able to get a second Body corp involved due to this fact.

47 minutes ago, jharber said:

Hello all

I'm working with my body corporate on a whole-block grid-tied PV system with battery backup. The idea is that the economies of scale of 41 flats will change the economics for us, and even more if we can team up with the neighbouring building of 68 flats.

Has anyone else been involved in something like this? We're looking for a power-purchase agreement setup from a specialist company. I'd be interested in hearing about other people's investigations/experiences/prices/etc.

I'd also be interested in any links to panel and battery calculators (or just excel models) that can cope with the numbers involved (12000-25000KWh depending on the month) since they all seem to cap out at amounts for single-dwelling mega-users.

Thanks!

J

Firstly, a deal with the block next door is going to fall foul of the law. OK, maybe you want to take the position that it's only a problem if you get caught. But also what happens when the occupants of one block decide that it's the guys next door who are using more than their fair share of the juice?

Many years ago I lived in a rent controlled flat. The owner of the block used to get a bill for the whole building and split that across all the flats (each flat had their own submeter, but these weren't read). 

There was unhappiness because it was known that in one flat a lot of baking was going on. In another the occupant left all his lights burning all the time. I was in one of two bachelor flats in the building, why was I paying the same as a person with a 2 bedroom flat with 3 people living it? Etc etc. The landlady soon had a fight on her hands. Muggins here volunteered to read the sub meters. After all, it's not rocket science. I soon had neighbours pounding on my door demanding that their be re-read NOW! They can't possibly be using that much etc etc

So I think even doing it for one building, the body corporate is making a stick for their own back.

How do they track who got the biggest bonus from the system, because it's a dead cert that not everybody has the same loads.

Tenant jharber might be careful with his usage, keeps his geyser under control, and is generally thrifty.

Meanwhile tenant bobster keeps tropical fish for a hobby, which means a heated tank. Oh and he has a couple of spotlights trained on that tank so the fish can be seen at their best. And he likes his electric blanket, and his wife is baking all day long because she sells at the tuisnywerheid to make some extra. And boy does that microwave oven ping all day!

And then you get loadshedding, and the one or two bobsters in the building soon deplete the battery and then nobody has anything. 

Sorry to be a bucket of cold water, but I think there are lots of problems looming on the body corporate's horizon. You could put meters on the feed to each flat, but even then what are you going to do? Tenant bobster really likes his tropical fish. Without those fish, life has no meaning. He's not draining the batteries deliberately, but what would you have him do? Poor piranhas... they have a right to a comfortable life, don't they?

Heaven forbid that somebody gets an EV and charges it every night.

OK... you don't have to get as cynical about it as I do. But the Body Corporate should discuss these issues and go into this with as much information as possible. And then they must tell the tenants how the game will be played. You'd need to split the DB in each flat (no geysers, no ovens), tell people what they can and can't plug into the sockets that are backed up and expect them to be adults about it.

Another tale from my own life. I used to work at a hospital near Melville. Melville was a dodgy proposition in those days (late 90s) because a lot of buildings had been repurposed into clubs and restaurants without proper planning (or maybe no planning and no permission) and the infrastructure which had been designed for a residential area was suddenly having to handle higher than planned for demands. 

So the power used to go down fairly often, and so the hospital bought a nice big generator. And every ward and every office had red sockets that were backed up by the generator. Essentially the backed up circuits were lights, the red sockets (supposed to be used for computers) and the operating theatres. 

But then they ran into more problems. The generator coped less and less well. So the hospital manager decided to see what was going on. Well... you can buy those red plugs with the chamfered earth pin easily enough. And people would buy a red plug, fit it to an adaptor strip, and would keep their under desk heater going. He also found some tea urns backed up in this way (on long extension leads because there were no red plugs in the kitchens). One of my colleagues got clever and bought in a toaster so we could at least have some hot toast with our tea when the grid was down. This is just in our department. Who knows what he found across the whole hospital complex.

So then there had to be regulations passed as to exactly what you could connect to red plugs, and how many of each item could be connected to any wall outlet. Etc etc... 

Then there was a secondary generator that was supposed to feed the server room only. You can imagine. We all get a talk about the difference between a "server" and a toaster, kettle or microwave oven.

Thanks for the quick replies, everyone. @87 Dream I'll be dropping you a message.

Noted everyone's response re: the legality of two buildings doing this together, that's very important to know—so thank you.

I should say that in general we're not inventing anything new here, either technically or institutionally. There are companies that do collective solar, we've approached a few for quotes, and we're going to go with one of them—I'm just trying to educate myself as a prospective client. @Bobster it sounds like that building owner screwed up pretty badly. We, like a lot of buildings, pay a single municipal electrical account and flats get billed by the body corporate based on individual usage—changing the origin of the power going into individual meters needn't *in principle* change anything about how that works, although we all know that things can go wrong in practice. So don't worry—tenant bobster with his tropical fish will pay his fair share!

I would think grid tied and a large diesel generator for backup if needed, don't go with shared batteries. Not sure if there are microgrid options with a generator so the solar can stay online?

The big qeustion here is, is this in Eskom area or COCT area.  Does this block of flats have a bulk meter supply point or individual metering from Eskom or City of Cape Town.

In the COCT there is differant rules for PV on a bulk meter point and induvidual meter points from City of Cape Town.

If the block of flats have a bulk meter point COCT sees it as one solar installation.  With does comes rules as well.  When the exspoprt capasity is 30kVA or more and there is more than one inverter a central disconnecting device must be installed with a out of bounds relay.  When the export is 100kVA and more SCADA must be installed so that it can comunicate with COCT.

 

 

19 hours ago, jharber said:

@Bobster it sounds like that building owner screwed up pretty badly

Such situations were not uncommon in those days. The City of Johannesburg had introduced a mechanism known as "rent control" which was intended to curb the excesses of unscrupulous landlords. The maximum rent per building was capped and the landlord had to provide a stove in every flat. But since their income was capped, they mostly weren't interested in spending lots of money on admin or maintenance.

The nadir was reached in another building not far from where I lived, where a young woman was electrocuted. There was no earth leakage in any flat in her building (nor in mine), just the old fashioned fuse boxes with the fuses consisting of a length of wire stretched across a ceramic bobbin (I had the same). The matter went to court, with the municipality saying that the landlord was culpable and the landlord fighting back on the basis that you cap the rent I can charge and then expect me to rewire the whole building at my expense.

This was in the early 80s.

The building I lived in had been inherited by the then landlady. She didn't have much of a clue about running a rented building and was loathe to spend any money on repairs or maintenance. There was nearly a fire when the main DB for the building (also composed very old fashioned fittings) overloaded and one of the circuit breakers did not do it's job.  But the general situation was not unusual - there were lots of buildings owned by individuals who had little appetite for running a building and certainly weren't going to modernise because they'd lose money in doing so.

The unforeseen consequence of rent control was buildings all over the city that fell into disrepair and, as noted above, sometimes into a dangerous state. The owners could sell, but the controls stayed in place and so any prospective buyer would either do their homework and decide it wasn't worth the investment, or some clueless person would buy and then find out they couldn't make the money they had imagined they could.

The worst case was that your building would fall into the hands of somebody who lived elsewhere, cared nothing for the neighbourhood you lived in and wouldn't do so much as oil a squeaky door hinge, let alone get leaking pipes fixed. Landlords could pass water and electricity costs on to the tenants, so if a pipe on the property was leaking then why waste money getting that fixed when you can make the tenants pay for the increased consumption? A new coat of paint on the building? Forget it. Leaking roofs fixed? Go buy a bucket. The more devious landlords would set up chains of trusts and close corporations so that you could never be sure who owned the building anyway.

The seeds of urban decay were sown early in Johannesburg. 

 

On 2021/08/18 at 1:22 PM, jharber said:

Thanks for the quick replies, everyone. @87 Dream I'll be dropping you a message.

Noted everyone's response re: the legality of two buildings doing this together, that's very important to know—so thank you.

I should say that in general we're not inventing anything new here, either technically or institutionally. There are companies that do collective solar, we've approached a few for quotes, and we're going to go with one of them—I'm just trying to educate myself as a prospective client. @Bobster it sounds like that building owner screwed up pretty badly. We, like a lot of buildings, pay a single municipal electrical account and flats get billed by the body corporate based on individual usage—changing the origin of the power going into individual meters needn't *in principle* change anything about how that works, although we all know that things can go wrong in practice. So don't worry—tenant bobster with his tropical fish will pay his fair share!

Yes the tenant just pay his bill as usual and it does not matter where the power come from.  There are private meter reading companies that handle that and they make money between the bulk supply rate and individual higher rates.

Few questions:

- With grid tied you only have power when the grid has power. Do you plan to overcome this somehow?

- With residence as opposed to office block a large portion of the power usage will be at night when you don't have sun power. What is the plan for this?

.

Edited August 19, 20214 yr by Bobster
nonsense deleted

On 2021/08/18 at 12:00 PM, 87 Dream said:

Busy with a similar project for 60 apartments. The energy requirements are more like a 100,000kWh grid tied inverter. You cannot do the two at the same time. The economics are crazy. You cannot add batteries to a Grid tied inverter. You can only do this with Hybrid inverters. The cost of the hybrids is double the cost per Kw of the grid tied. However, you need to start somewhere to get the ball rolling. Because paying Eskom crazy money for electricity is madness.

This is interesting. So the concept here is centralised generation and then distribution to each unit? 

If it's grid tied then all the billing issues I foresaw go away. If batteries are involved then there has to be a way of monitoring what each unit drew from batteries and possibly limiting how much any one unit may draw.

Thanks for that detailed reply. It's an interesting scheme, and a long term winner because the value of units in that complex is going to go up.