Just curious, for now.

[Drunkard #1]

I'm looking at a small PV installation. It'll be on top of a new factory structure. PV panels for about 12 kWp, over 80m².

Q1. I'm at 26°S, so almost flat in summer, and around 60° in winter. Averaging out at 26°. Should I tilt more to compensate for the shorter winter days? (It'll be a fixed installation, no tracking.)

Q2. Should I compensate (by less tilt) for being slightly off north? I'm only 11° West off.

Q3. Is ye olde $1/W still valid for a thumb suck price on panels?

Q4. It's a factory, so night time use is low. Also, it'll have a grid connection that will provide most of it's energy. What do you think about 4 x 100Ah batteries?

Q5. What sort of cost am I looking at for Outback inverters, controllers and battery chargers?

Q6. Is grid tied an option in Ekurhuleni, or must this installation be entirely isolated from the mains supply? Maybe just used for lighting and office?

Do you think this will be worth it? R 200k investment (?) for a R40k/y (max) saving. I'm cheap, so I'll do this cheap - no fancy expensive engineers on this project.

Thanks.

 

[HavocXphere]

200k investment and just using it for "lighting & office" sounds a little crazy to me.

No afaik doesn't need to be isolated, but I believe you need a device that integrates the mains feed & solar and that thing...whatever its called is not cheap.

 

[Drunkard #1]

200k investment and just using it for "lighting & office" sounds a little crazy to me.

No afaik doesn't need to be isolated, but I believe you need a device that integrates the mains feed & solar and that thing...whatever its called is not cheap.

R 200k (I'm working on R 120k for panels and R 80k for inverters (R 30k), batteries (R 20k) , mountings (R 20k), etc, etc.) would produce 26 000 kWh/y - at current Ekurhuleni business prices, that's R 46 000/y, if I can use all the power it generates. That's why I'm looking at fully integrating it - if I can't, I might set up a much smaller system for lighting and a few other non-essential uses. I know that Ekurhuleni doesn't like small generators plugging into their network, hence my question about grid tie.

Right now we're still in the planning phase (of the entire building, not just the PV installation). We also need to decide what we're going to do with the building - rental or use it ourselves. If it's rental, we'd need to sell the power to the tenant.

 

[BandwidthAddict]

If you're planning a new building, I would recommend planning an energy saving building. Think insulation for the parts of the building that are heated and cooled. Think about orientation to make use of natural heating and cooling. Think about using piped lighting that brings sunlight into the offices so you don't need office lights on during the day.

 

[BandwidthAddict]

Also think about putting in showers for employees so they can cycle in to work if this place is located near where people live. Also a small gym so employees can stay fit and reduce sick leave.

 

[HavocXphere]

R 200k (I'm working on R 120k for panels and R 80k for inverters (R 30k), batteries (R 20k) , mountings (R 20k), etc, etc.) would produce 26 000 kWh/y - at current Ekurhuleni business prices, that's R 46 000/y, if I can use all the power it generates. That's why I'm looking at fully integrating it - if I can't, I might set up a much smaller system for lighting and a few other non-essential uses. I know that Ekurhuleni doesn't like small generators plugging into their network, hence my question about grid tie.

Right now we're still in the planning phase (of the entire building, not just the PV installation). We also need to decide what we're going to do with the building - rental or use it ourselves. If it's rental, we'd need to sell the power to the tenant.

Thats going to be rough since you don't know what kind of needs the lessee will have.

>Right now we're still in the planning phase (of the entire building, not just the PV installation).

Well thats good...then you can make sure you've got the right mountings on the roof instead of retro-fitting.

>I know that Ekurhuleni doesn't like small generators plugging into their network, hence my question about grid tie.

No you def can't feed back into the grid, but as I said afaik its possible to run off solar and pull the extra bit you need off the grid (hence that device thing)

 

[Drunkard #1]

Also think about putting in showers for employees so they can cycle in to work if this place is located near where people live. Also a small gym so employees can stay fit and reduce sick leave.

If you're planning a new building, I would recommend planning an energy saving building. Think insulation for the parts of the building that are heated and cooled. Think about orientation to make use of natural heating and cooling. Think about using piped lighting that brings sunlight into the offices so you don't need office lights on during the day.

Going green is almost the norm these days. Obviously we'll be including the usual - polycarbonate panels on the roof for light, foil for insulation, natural ventilation, solar geysers, etc. Even a small PV installation is common, but this kind of goes beyond that.

Thats going to be rough since you don't know what kind of needs the lessee will have.

Our risk, obviously. It's a tiny factory, so it's not like they'll be setting up an aluminium smelter.

>Right now we're still in the planning phase (of the entire building, not just the PV installation).

Well thats good...then you can make sure you've got the right mountings on the roof instead of retro-fitting.

I'm not so sure. Fancy mounting needs fancy detailing, and that means roof leaks. It might be easier to design the structure so that the system just sticks to the IBR. Safintra offers something, and I'm sure General Profiling could cut and bend something for a reasonable price.

>I know that Ekurhuleni doesn't like small generators plugging into their network, hence my question about grid tie.

No you def can't feed back into the grid, but as I said afaik its possible to run off solar and pull the extra bit you need off the grid (hence that device thing)

What I asked them (a while back when we were having tariff issues) was, "Can I hook up a genny to make sure my peak doesn't exceed a certain kVA." They said, "No, any generation needs to be completely isolated from our network, ie, if you see your peak is going to exceed that value, you need to switch entirely to genny." That was resolved when they introduced a new tariff, but it's now relevant for small PV.

 

[HavocXphere]

I'm not so sure. Fancy mounting needs fancy detailing, and that means roof leaks. It might be easier to design the structure so that the system just sticks to the IBR. Safintra offers something, and I'm sure General Profiling could cut and bend something for a reasonable price.

Ah no I didn't really mean fancy mountings...my point is just that these things are pretty heavy so you do need a reasonably solid structure as a baseline....and building that into the roof design is much easier than figuring it out & retrofitting later.

Personally I'd not attempt to fit PVs straight to IBR due to easy maintenance & structural strength, but thats just me.

What I asked them (a while back when we were having tariff issues) was, "Can I hook up a genny to make sure my peak doesn't exceed a certain kVA." They said, "No, any generation needs to be completely isolated from our network, ie, if you see your peak is going to exceed that value, you need to switch entirely to genny." That was resolved when they introduced a new tariff, but it's now relevant for small PV.

afaik generation needs to be isolated just means you can't have anything feed back into the grid. e.g. I know there are business using huge battery packs to chop the "peaks" off their usage. If you're DIYing a solution without engineer involvement then an isolated version is probably the safest option.

 

[itareanlnotani]

Panels are straightforward.

Panels and mounting is easy to organize.

I'd actually look at getting everything from China - thats what I did, as you can pretty much halve the cost of what the local pricing is. 40 Panels will be about 4cbm, may as well ship a container. Container + clearance is about 32k rands. + duties +vat + unit cost.
Can PM me for further details on that if interested. Most panels are imported from China anyway, even the cough cough, "locally" made ones use imported solar cells from China...

If you do ship a container, ship over lighting as well (LED lights are dirt cheap in China, compared to here).

There are currently no duties on Panels or inverters.

The complicated part is how you take the power out. Eg grid tied, or off grid, or hybrid.

For a factory setup, I'd suggest 3 phase inverter(s), as most factories will need 3 phase.

Issue here is that you can't really feed back into the grid. Strictly speaking, yes, you can, but lots of paperwork involved, and the costs don't make sense, as Eskom is anti-solar to be honest., so either you go offgrid, or you have a system thats "on-grid", but doesn't feed back into Eskom/local supplier.

I'd probably suggest going Grid-tied, but not feeding back into the grid. - eg any excess gets wasted. This probably makes the most sense for you cost wise. There are downsides to this setup - if Eskom goes down, so do you, as grid-tied goes off when the grid goes off for safety reasons. Price wise though, its the cheapest to implement.



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12KW of panels = 40 x 300W panels
Panels are 2 x 1M in size, so you should be able to fit in your 80M roof space.

Assuming you have something similar to mine, they'll be 36.6V / 8A panels (300w panels)
You'll probably run them in 2 or 3 strings.

A string is a bunch of panels tied together. Usually you'll run panels in series for a higher DC voltage to the inverter.
So 20 panels as one string = 732V @ 8A = 5.8KW out for each string.

You'll need to size the inverter(s) based on that sort of voltage. You can play with how you size the strings though, but you'll need to work on that sort of calculation.

Also remember that your output is going to be quite different for summer and for winter.
Eg, in Summer, you'll get quite good output - 12KW of panels will give you 12KW peak at lunch, and lower throughout the day.

You'll probably go from about 25% in the morning in summer from 7am, through to 100% at 12-3pm, then back down again till about 6-7pm.

I have 4KW of panels on my roof, and I get about 25KW and more out per day during summer.
Winter I'm getting between 2-12KW depending how overcast it is.

You'll get about 3x those values, as you'll have 3x as many panels, so summertime you'll have excess galore, and winter time, insufficient.

Again, I'd suggest Grid tied, as you can pull in whatever excess is needed from the grid when you're not generating enough, and not need to spend on batteries.

I've got lots of info about my own solar install here - http://goingsolar.co.za

Feel free to ask more questions though.

 

[Drunkard #1]

Ah no I didn't really mean fancy mountings...my point is just that these things are pretty heavy so you do need a reasonably solid structure as a baseline....and building that into the roof design is much easier than figuring it out & retrofitting later.

Personally I'd not attempt to fit PVs straight to IBR due to easy maintenance & structural strength, but thats just me.


afaik generation needs to be isolated just means you can't have anything feed back into the grid. e.g. I know there are business using huge battery packs to chop the "peaks" off their usage. If you're DIYing a solution without engineer involvement then an isolated version is probably the safest option.

I see that panels are <20kg/m². Glueing the mounts onto IBR will work just fine.

Panels are straightforward.

Panels and mounting is easy to organize.

I'd actually look at getting everything from China - thats what I did, as you can pretty much halve the cost of what the local pricing is. 40 Panels will be about 4cbm, may as well ship a container. Container + clearance is

<snip>

You'll get about 3x those values, as you'll have 3x as many panels, so summertime you'll have excess galore, and winter time, insufficient.

Again, I'd suggest Grid tied, as you can pull in whatever excess is needed from the grid when you're not generating enough, and not need to spend on batteries.

I've got lots of info about my own solar install here - http://goingsolar.co.za

Feel free to ask more questions though.

Thanks for the info. I'll get hold of a few exporters closer to the time. I agree that grid ties without feed in is best. Surely there's a way to automatically isolate the grid when there's a power failure.

I'll keep this thread updated when things progress.

 

[Polymathic]

Until Eskom starts to pay people for adding power to the grid don't bother

 

[itareanlnotani]

Until Eskom starts to pay people for adding power to the grid don't bother

The price for generating electricity is cheaper than buying it from Eskom, and the difference will be worth more and more over the lifetime of any system. That alone makes it worthwhile.

As a home user we use around 15KW daytime, 10KW nighttime. You can install a system 4KW of panels, and can on average reduce daytime use to zero. More savings can be made by judicious use of your "free" daytime electricity - eg moving higher loads to daytime use (eg heating up the geyser during the day, or doing washing and cleaning during daylight hours).

I'll be fair and calculate that out at 20 days a month output. Thats 15KW x 20 = 300KW a month saving.
Thats 300KW x 153.86 = 461.58 a month at current rates saved a month.

System would be something like 15 x 300w panels + inverter + ATS to stop excess going to grid. That can be done for about R60,000 if you source appropriately. If you wanted to extend this to go into nighttime also, you could add batteries to either side of the inverter for about double the cost.

Assuming its just daytime, its pretty much zero maintenance to save R460 a month at current rates.
Life of system is in the 15+ year range (panels have 20+ yr lifespans, and inverters 10-15years).
It also makes for a higher return on investment than the cost of the system.
Assuming pricing goes up year on year for electricity, each year it makes even more sense.

As a business user, most of the electrical usage is daytime, so it makes even more sense.


It makes *even* more sense when you can give back to the grid, and pull back from the grid, but it still makes sense without that.
Eskom is playing a dangerous game. Their continual price raises will encourage more people to go solar, and eventually bypass the grid completely.