Finally, out of frustration cause by load shedding, I decided we need backup power at home. However instead of spending the money just on convenience, I wanted the system to pay for itself. That meant installing panels also.
- Have power on all plugs and all lights in the house for min 2 hours
- ROI of max 5 years
- Spend no more than R30k
- Use as much of generated power as possible for own use
- Not go grid-tied because of extra paperwork and additional cost for meters
- Able to expand to 10kva or more
- Not changing exciting appliances and geysers.
The above constraints meant that some rewiring was necessary to ensure high use equipment is connected to the PV system during the day but not when there is a power failure. It also implied that I had to buy inverter When I started the project my aim was to spend around R30k in total.
Is R30k a realistic target?
Well figured there are three big components, batteries, inverter/charger/mppt and PV panels. I just allocated R10k to each of the components. Did I mange to stick to the budget? Not really and there are a few factors that impacted on the final cost:
- I wanted the system to work seamlessly and that meant spending money on an electrician to change the DB board in the house. (I am still waiting on a final cost for this work)
- The house roof is not north facing and meant the cheap mounting options was not available. Possible saving of R1125 per 6 panels.
- I bought more expensive mounting system just because It was available immediately. Possible saving of R1100 per six panels.
- Also to speed things up, I bough ready made battery cables and a ‘integration box’ with fuses. I am sure that savings can be made if buying these separately. Possible saving of R860.
To sum up, if the roof is suitable and you don’t buy read made kits, R30k is possible.