Elbow

Thanks guys for the advice - really appreciate it. I have put some EmonCMS monitoring on my board and I'm gathering some stats - I'm going to use that to really understand my load profile and that should help figure out exactly what I need. Once I've got a few weeks data I'll post the data and my analysis for comment. Right now it shows my geyser using between 9 and 14 kWh per day, and everything else using between 15 and 20 kWh. I have an old Intel server running as a NAS and that uses a steady 230W so that is really costing me - 6 kWh of that total. So decision one: solar geyser, "power dump" element off PV, or heat-pump to deal with the hot water. And replace that old server with something more efficient. Anyway - thanks for the help with the battery question. Steve

Hi, I have one of the Renesola 3KW hybrid inverters from Bonanza's current special. Well, actually I have 2... Couldn't say no at the price. I had in mind to use it with 8 x T105RE batteries, but comparing the inverter specs with the recommended charge for the batteries I see the inverter comes up short in maximum voltage. The batteries want 59.28v for bulk charge (never mind 64.8 to equalise). The inverter maxes out at 58V Amps wise the inverter can deliver 25A which I think will be sufficient. But I'm guessing that the voltage shortfall will mean my batteries won't get 100% charged. And I can't equalise. What are my options? Would it be OK as is? Is there a way to mod the inverter to get that extra 10% voltage? The main benefit of the hybrid inverter is all the functions are integrated, but is it possible to use a different charger? alongside the machine. Otherwise I guess I need to find different batteries. Thanks, Elbow

Thanks for the input. So - thinking aloud..., and using guesstimated numbers (who can help me with better estimates?) Lets say I put up 10x300Wp panels or 12x255. So in theory I have 3kWp. Theoretically 15kW/h average per day? Reading here I think that's too optimistic, so lets say 12. (The pros can help me with realistic figures?) Option 1 is pure off-grid, no batteries: If I think about a pure off-grid system with no batteries It seems to me it will be difficult to use all the energy. Reason being that it must be used when the sun is shining, and we must stay within the available power at all times. So I would guess that I could maybe use half (6kWh) in a day on average. What do people think? The advantage being that the system is relatively cheap. I could even reduce the number of panels and maybe build a starter system with limited power for under R30k. But all the panels with inverter for maybe R40k? To try to get the most out of it I would build a control system that measures available power (Openenergymonitor or data from inverter) turns things on and off as there is power budget. (Using relays or Sonoff wifi switches). What "things"? - non-critical items like the pool pump, maybe a low power geyser heating element? Run the washing machine on a sunny day. If it is 6kWh saved per day then we are talking about something like 180kWh per month which is about R470 today. R40k capital saved us R470 per month. It'll look better later if electricity prices continue to rise faster than inflation. Option 2 adds feed-in from the grid: So I connect my inverter to the grid with the reverse blocking device. Still no batteries. CTCC installs pre-paid at their expense. Let's guesstimate we spent now R50k with the extra hardware and the PrEng signoff. So now I don't have to worry so much about overloading the PV since the Infinisolar will "top up" shortfall from the grid. So we can use all the daytime power we make up to the demand (rest wasted). But still, daytime demand isn't that high, even with effort to move load to the daytime. Let's guess we can now use 8kWh off the panels. 240kWh/month or R625. R50k capital saved us R625. Option 3 is full grid-tie: So now we need the fancy new meter too. But we don't need the reverse current blocker. So R55k total? We're on the SSEG tariff - so paying CTCC R400 standing charge, but our first 600kWh quite.a bit cheaper. So how this turns out depends on total consumption. We make 12 per day, use 8 ourselves so sell the excess 4 back. So 120kWh per month or R84 (whoop-de-do). Assuming 800 kWh/month total consumption we are still buying 800-360=440. That costs us R512. So 400+512-84= R828. 800kWh at domestic tariff would have been R1580 so R750 saving having spent R55k. So - a lot of abouts and guesstimates, but based on all that the option 3 has the best return. But there's not much in it. Next is to think about batteries. I suspect that will push the balance back to option 2 - But another post...

Thanks - I did see that the Infinisola is approved, though mine is branded Renesola so hope they agree that its obviously the same thing. I did read other CTCC documents but I didn't see that document so thanks! Elbow

Hi everyone, I've been reading so many posts here trying to get myself orientated. I've recently bought a new house and wanted to get some PV panels up and run some of my load from the panels - at least some of the time. I had in mind the pool pump (which can run in the day) to start with. Maybe the dishwasher which can also run in the day, and then some lighter loads depending on how things go. I'm waiting on some openenergymonitor hardware to arrive so that I have good data on what draws what. But the practicality of the PV system does depend on how you make up the shortfall - ie load beyond available PV power I had the opportunity to buy in Infinisolar 3KW hybrid invertor. I grabbed that chance since it is very versatile and much under list. But now engaging with the CTCC rules and all and the trade-offs seem very complicated. My new house has an old analogue credit meter. It seems it not OK to connect my hybrid inverters grid input to that even if I program my inverter not to feed back. Do I understand that I either do not connect the grid input at all - so a completely off grid system, or I choose either: Switch to a prepaid meter (my cost), and add an isolator to prevent the feed in (what device, and how much?). Now I can draw from the grid with no chance to feed back. And I'd be on the standard pre-paid tariff. I'll probably need to buy some batteries ($$$) to "time shift" my daytime excess energy into the evening. Or: Switch to a "both ways" meter (my cost - and how much?), switch to the feed-in tariff (R350-ish standing charge and probably well under R100 feed-in credit?). But I don't immediately have to buy batteries which is a big capital saving. Do I also need a Ziehl or other sort of gear between my inverter and grid? In both cases the expensive services of a PrEng are required to certify the install. So it looks like a complicated calculation to figure the best approach, and in either case an expensive exercise to satisfy them. So for other Capetonians what have you chosen to do? Thanks, Elbow