Good day everyone,
So I've been seriously considering getting a solar PV setup for several reasons.
1) My wife is a developer who works from home, and I do on occasion too, and with the load shedding it's becoming more prevalent to have some form of backup solution, other than a very expensive (and super noisy) generator (which incidentally now needs a service).
2) The climbing cost of electricity.
So what's held me back is, that I've been trying to cut my usage where possible, before I shell out ridiculous amounts of money. Now, however, with the increasingly high chances of Load Shedding again, I've decided to make the call and "Just do it". So I've managed to cut some costs, 3x geysers converted to solar, gas hotplates, but I've also decided to change what I was originally planning, by trying to be off-grid as much as possible, and only use the grid when loads are high or when batteries drop below a certain point (provided Eskom power is available).
I was looking at the same system that another poster was looking at, with a full 10kWh Lithium battery bank and extra panels.
With this change, I have a series of questions:
1) What happens when you draw more than the rate 4.6kw of the inverter (eg tumble dryer + washing machine + dishwasher all somehow start heating at the same)? Will the load shift to Eskom (which is what I would want), or would the inverter disconnect itself (or what ever happens with overloading)?
2) Can the house be configured that when there is Solar energy during the day, or Eskom power during the night, have everything available to run (whilst drawing from batteries first at night up to 50% DoD), but as soon as Eskom isn't available and the batteries are at 50% or less, have the load restricted to certain plugs and lighting etc. I understand it would involve some significant rewiring of the house, but I'm curious if it's possible.
3) Aside from the cost obviously, is there such a thing as too much solar? I'm asking as with a 10kWh battery bank, I'd need to charge min 50% of that during the day, as well as cover my load as much as possible, and I'm in the process of making changes to the way we work with regards to appliances (eg Tumble Dryer), but until that happens I'll be trying to get the solar installed. Also I want to cater for winter, when generation will be lower (I've discovered this the hard way with solar geysers).
4) As a follow on from point 3, the inverter that is included in the Kit I'm considering, rates max MPPT input of 6500Wp. My house is in a NE orientation, and I would have some panels facing NE, and some facing NW. I'm not sure exactly how many I could fit on each side, as I'm not sure on the mounting requirements etc, but I estimate I could get 8 on the NW facing side, and potentially 14 on the NE facing side, which totals 22 panels and 7260Wp. I feel the chances of getting the max power out of the panels is low, due to being in Jhb, and the panels not necessarily being at the optimum angle, and the peak power from each string being at different times of the day.
5) Next comes the issue of where the inverters and batteries will live. So I've read that you want the DC lines to be as short as possible, but the place I want them to live is a good 20m from the nearest side of the NW facing side, and 2 storeys and about 14m from the nearest end of the NE facing side. In the image below, the yellow box is where I'd like to put my Inverter and batteries, with the Red block (~9m x ~3.25m) being 1 string, and the Green (~3m x ~4m) and Blue (~4m x ~4m) being the other string. The Blue block is not bigger, as I've added additional geyser solar tubes, that come to approximately where the block ends. I'm not keen on putting the inverter and batteries close to the red block, as that is a not-so-closed "car port" area, and in heavy rains and winds, gets wet inside. Will 20m distance from panels to inverter on each string be a big issue?
6) In reality, I'm hoping to save around 80-90% of my monthly electricity bill in summer, and 50-75% in winter (heaters etc), which will in theory mean I could "pay off" the system in about 4-5 years at current electricity prices, but I'm curious what real life is like for people who have installed solar and batteries.
7) My current usage is around 30-40kWh per day currently in summer. Winter is still an unknown as I installed the geyser tubes in November last year, and last year winter usage was around 70-80kWh per day. I've managed to convince my family to use the heater less, this year, but I've yet to see how well that convincing will work. I'm hoping the geysers were the big one, as my summer usage dropped by 20-30 kWh per day, from the same time last year. So the question is, will this size system be sufficient, keeping in mind I'm still looking to drop usage further?
8) Has anyone also dealt with Solar Advice, Mega Solar or any of the online "distributors", and has negative or positive feedback with regards to them?
9) And lastly, are there any solar installers in the Ekurhuleni (or greater Gauteng) area that people would recommend?
Many thanks in advance.