Grid Tie Solar System Solution

[Hloni]

We've been mulling over power solution for our office for the past long while. Generator vs Solar, and I'm really at the final stages of opting for solar, being in Jo'burg and sun being plenty.

*CONCLUSION:*

Best setup would be solar, no battery bank, Eskom as back-up.

We've been monitoring our office hour consumption, and we peak at 3.2kw once a week (no air-cons or boilers or microwaves in this part of the office/DB.

Ellies (don't crucify me) has quoted around R80k for a 3.6kW setup, using Hoymiles Grid Tie Microinverter. I most likely can "pump back" into the line with the agreement from landlord so I can access any excess for nighttime passive running of office equipments. Our electricity bill is currently around R5k a month (1.5mWh), so will pay system off in 2-3 years which is a good return on investment for an NPO.

Would appreciate the minds of experts and hobbiest alike.

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[73type2]

A colleague of mine also installed a roughly 3.5kW solar system at his house, but he went the "Rolls Royce" route with batteries and online monitoring etc. He also worked out a payback period of about two years and is very happy about his investment. He is not pumping back the excess capacity to the grid because the municipality is charging a wheeling charge, meaning that you have to pay them for using their infrastructure to feed electricity into the grid. I think he paid much more than R80k for his system, so your quote sounds good, even if you had to add batteries.

[Tony Z]

Have a look at www.sustainable.co.za for more ideas and options

In my opinion, if you are using 3.2kW peak, you need around a 6kW setup. Panels loose efficiency over time, so after a year, you wont be able to keep up.
If someone switches on a kettle or uses a vacuum cleaner, or heaven forbid, they both happen at the same time, then the system has to go back onto the grid or if eskom is out, then your lights go out too.
Using batteries will get you around those spikes. But they add cost and they add maintenance.

And dont forget, the government is looking at ways to charge us for having panels, even if we go off-grid (lets not go political here).

[Hloni]

Thanks guys! We have x3 parts to the office setup, and this Phase 1 part really is an office, no kettles, no heaters, no element, just computers. Another part (separate grid/db) is where we have the kitchen, and a 3rd part is where we have our workshop. So the risk of the "sudden" spike is minimised, but between you and I, we know there is always that smart someone who will plug in an element without thinking, and then k@k gaan vlieg!!!

Regarding batteries, I'd love to get something that'll get me 60-90 minutes tops. Eskom remains my fail over! If it does so happen that eskom and sun is down, that must be a clear sign that we need to tidy the office and then go home!!!!

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