I’ve been reading posts on this site for a few days now, it’s a wonderful source of information for newbies like me. I of course have quite a few questions, if anyone could offer advice or info that would be greatly appreciated.
I’d like to mainly use as little grid power as possible during the day and charge some batteries enough to help offset some of the electricity costs during the evenings (keeping a bit in reserve for load shedding, when necessary). I’d like to keep the house running during load shedding/outages so the basic lights and plug points so fridges run and I can at least watch TV etc.
The current usage:
Daily avg last month (April) was 27kWh and over December that went up to 32kWh (aircon)
Efergy monitor seems to sit around 0.4kW when everything is idling. I'm in Randburg, Johannesburg.
The bigger power consumers:
Pool pump 0.8kW (runs 4 hours in winter and around 8 hours in summer)
200L geyser which is on a timer and runs for an hour at 16:00 and two hours from 5am. I sometimes manually override this if there’s been quite a bit of hot water usage in the morning and someone wants to shower later on in the day, not sure I need to but happy wife, happy life, so just playing it safe.
I have a 550W water pump (vsd) which is connected to two toilets (roughly 20 seconds each flush) to keep some water circulation from the backup water storage and it’s switched over to the whole house manually whenever there’s a water outage, this only runs when water is being used and it seems to be using 200W looking at my efergy
The electric stove, hob and extractor (Our extractor doesn’t, and can’t, vent to outside and doesn’t always get used when cooking so wouldn’t want to go gas from a health perspective)
The aircons 2 x 9000btu and 2 x 12000btu (all inverter type), these are only used in summer and generally only one at a time. Unfortunately one of the small ones in the bedroom is used overnight in warmer months, which without lots of batteries is probably going to be an eskom usage.
Espresso machine (1500W, I think)
High power kettle (3000W, I think)
Upstairs lounge - avr (650W), sub (400W) and lcd tv (180W), these are all max figures, there are probably spikes but with everything running, it’s normally about 200-300W.
I’m happy not having essentials like stove and geyser during power outages and I realise I’d have to carefully manage the draw of other devices or the system would trip. I monitored the Eferegy meter after load shedding and I initially had a spike of 700W this dropped down to 450W pretty quickly where it seemed to stay (obviously pool pump and geyser weren’t on).
The available roof space:
The one area of roof I have which gets the most unshaded sun on the 2nd story is pretty small roughly 6m x 4m so 24m2. It is currently in the sun from about 07:00 until after 16:00, the other areas are more difficult. I do have a much larger roof below the 2nd story one but it’s shaded by the 2nd story bit in the morning and then hit by some more shade in the afternoon from trees. There’s a decent section which will probably have 1 or 2 hours less sun than the 2nd story roof but it is roughly 6mx5m so 30m2. I then have a flattish roofed single garage which isn’t attached to the main house so cabling could be fun. It would be in the sun from sunrise until about 15:00 but I’d need to get some panel mounting system to raise them up slightly and angle them correctly and I guess with enough space between them to not provide any shade, this could be very challenging and expensive!
This probably varies but where do you guys mount your inverters, batteries, etc? I think some of the installs are works of art and would like to have them on a proud display in the house, my wife would disagree though So where have you installed yours? How much noise and heat do they make? How close to the db board do they need to be? My db board is currently under a concrete roof on an ‘island’ in the kitchen so I’m guessing there’s going to be a lot of electrical work.
Some inverters seem to have mppt controllers and others require separate units for those, if I went with a small solar array at first would I be able to easily add another array, possibly with another mppt if required at a later stage? And would the arrays need to have similar output or could one be larger than the other (would I need a separate mppt for this)? My initial thought was panels are the most efficient way to have excess solar (when the sun is shining) and cheaper than trying to store power so I wanted to possibly have two arrays on my roofs and try and move as much energy usage to peak times to hopefully minimise draw from the grid.
Inverters, there’s a lot of different brands, some seem to be well supported with older manuals easily available on their website (victron) which is reassuring. Some don’t seem to though like Sunsynk, which seems to be a popular choice, how did you pick your inverter, was it based on price alone?
From lots of reading on this site, the 8kW Sunsynk for example can draw and provide over 8kW of power if needed supplementing from the grid, so if I had a big spike of 11kW it would happily handle it? Just to check my understanding here but it could only provide a max of 8kW from the batteries (assuming a big enough battery/batteries) and solar excess, is that correct?
How did you determine the sizing for your inverter, it seems like having some headroom would be a good call but it sounds like you could theoretically place another inverter in parallel down the line if you can manage to find the exact same one is that correct?
I was thinking of starting smallish on the battery front with something like a 5.5kWh battery which hopefully should give around 4kWh of usage at around 80% DOD and when funds allow possibly add another, is that a good plan or should I just take the upfront hit and get a bigger battery or multiple batteries now? Also lots of different battery manufacturers, how did you choose yours?
The panels seem to all come in different sizes and power ratings. I’m dealing with a smallish roof area so I think I’d have to go with some pretty high wattage panels to try and maximise generation for the space? The different sizes make working out what would fit really annoying. I will be mounting to a tile roof, how do you mount the panels and how close to the edges of the roof can they be?
I’m on a postpaid smart meter with city power and I have no intention of feeding back to the grid. Am I in any way limited with the size of the solar array I am allowed to install?
Installers, how did you choose yours? it sounds like there are quite a few less knowledgeable installers out there and I’m definitely going to need someone who knows what they are doing.
If you got this far, thanks so much for reading this, any advice/answers would be great. I hope to have a system up and running as soon as possible