February 27, 20197 yr Hi All Firstly what a great Forum, i have been toying with the idea of going solar for a few years now however the main reason i have not is due to total confusion as each solar person/company i ask advice from seems to differ so i eventually just gave up. The time has come now to do it as i my electricity bill is large and i am pretty certain is gonna go up in the short term due to issues at Eskom. My situation is as follows i am currently using in the region of 60kwh electricity per day of that the majority is daytime use +- 45kwh between 7am-4 pm. I have a solar geyser, all my house lights are led and want to reduce my electricity bill. System requirements for me are the following: To Use solar to power all of my electricity requirements in the daytime (+-45Kwh) to reduce my electricity bill which is currently around R5000/month 😞 I currently have a 7kva generator wired to an essentials circuit, and would like enough batteries to power this for 2-4 hrs instead of using the genie. (Lithium batteries). If i cant afford all the batteries at this stage i plan on going with 2 or 3 of the pylon batteries to start (2.3Kwh or 3.5kwh ?) I am currently on a old prepaid meter so plan on upgrading to a bidirectional prepaid meter at some stage and have excess power pushed back into grid for credit. So system needs to cater for this. I live in Pretoria and apparently in the next couple months these bidirectional prepaid meters will be available. Would like to be able to expand the system as money allows without having to change existing components. I would like to be able to remote monitor the system My electrician connected a device to my DB and measured my amp usage over a number of days as a matter of interest which i have uploaded to this post. So my question is what would you recommend i go for in terms of inverters etc. I initially looked at the Goodwe 5kwh however i believe this wont be sufficient for my needs and apparently one cant add another Goodwe without setting up a seperate circuit for the 2nd inverter? Would be great if i can get some feedback in terms of recommended components i would require to power and setup the above? Apologies if i have used any incorrect terminology im a Solar infant and dont know much about electricity either.
February 27, 20197 yr Author Would the below be recommended for my needs as explained above? Battery Monitor BMV-712 Smart Quattro +48/10000/140-100 Blue Sol MPPT 150/70tr 330 Watt solar panels (Canadian Solar) x 20 2 x pylon 2.4kw batteries Question with the above, in a scenario where i don't utilize all the power generated from the solar in the day, my batteries are fully charged and i dont have a bidirectional prepaid meter installed as of yet (so im not feeding back into the grid as of yet) might be a silly question however what happens to the extra power generated?Can the above components see everything is full and put the whole system into a stanby mode of sorts?
February 27, 20197 yr Rough thumbsuck would have been for around 10kW of panels (eg 40x250w panels) to cover the daily power demand of 45kWh. And facing slightly North-East to get early-morning sun, considering that the majority of loads occur quite early already. With just about 5kWh of backup power initially it's probably far undersized to go off-grid with that amount of power required. 2x5kW grid-tie inverters? Not sure if that's allowed residentially. Layman's 2c. Pinch of salt required.
February 27, 20197 yr 45kWh is a lot, you can surely cut that back a bit? Its generally the many small appliances that are on 24/7 that contribute to the 'base load' , once you have sorted out the geyser. Its cheaper to be efficient, that run your inefficiency on solar. At 2.00 in the morning you are pulling 5A, so at 220V that is 1kW. If you can shave 5A off your load every hour of the day, that is 24kWh per day less that you have to power. Edited February 27, 20197 yr by DeepBass9
February 27, 20197 yr 2 hours ago, SheldonB said: might be a silly question however what happens to the extra power generated?Can the above components see everything is full and put the whole system into a stanby mode of sorts? Not a silly question at all. no extra power is generated. The power generated is load dependent. If no load is drawn, no power is generated. So effectively, when the battery's are full and loads are low, it almost goes in to "Standby mode" waiting for some load to demand some production again. Hope this makes sense to you.
February 28, 20197 yr Other 2c layman's question, how much of the load is definitely essential backup? If there's a 7kVA generator, is that overkill or barely coping? Will the backup power output of the Goodwe ES (4.6kW) not be enough to feed into whatever is on that circuit? And then be satisfied with just reducing the bill by less, or finding loads to cut back on? Other 2c to check/consider, if you want to export or grid-tie above 4.6kVA, you may have to go 3phase, so maybe a 10kW 3phase hybrid?
February 28, 20197 yr Author Thanks for the replies everyone, i already have a solar geyser all my lights are led, i have a gas top however oven is electric. Staff have gas stove and gas water heater so no hotplates.This is my home. I am powering the following: Pool pump (1,1KW) Heat Pump on pool (12amps) Borehole pump Pressure pump 24000BTU aircon (Nightime only) 3 x fridges (Have live in staff) 1x chest freezer Washing machine Dishwasher Electric oven (Gas top) Microwave 2 x LED TV's Alarm Electric Fence One can see on the graphs when the pool pump and heat pump kick in around 7:00 am each morning till 4pm each day. These 2 items are the main energy consumption hogs in the day. Has anyone installed those black solar heating panels one puts on the roof? I'm thinking of taking out the heat pump as that alone is 12amps! For a residential installation are you allowed to have more than 5kw grid tied?
February 28, 20197 yr I have 200m of black pipe lying in the field next to the pool that the water circulates through. It keeps the pool at 27-28 degrees. Not a suburban solution though. It is more efficient to passively heat the pool with solar, rather than using PV and a heat pump. Edited February 28, 20197 yr by DeepBass9
February 28, 20197 yr 4 hours ago, SheldonB said: Pool pump (1,1KW) ... and all the rest An idea is to split the systems. For example:Solar air conditioner and use Eskom at night. Batts are too expensive for that. Solar pumps for the borehole or some such. Alarm / Electric fence on a smaller dedicated solar / Eskom / battery system. Electric oven keep on Eskom - in my opinion it is not worth the cost for the times it is used per year, and it pushes everything else up. Fridges and Freezer is A++ or even A+++ - that save a LOT in power per annum. Most of us upgraded these things first, or soon after. Heatpump - that is why I went EV tubes, and I don't use the precious max inverter size and panels for heating our main geyser. Going about it another way, your system becomes smaller and cheaper overall.
March 6, 20197 yr One can have two Goodwes but their backup supplies need to be separate. So one can think of it as a tree with the "mik" low down and each inverter supplying a separate set of essential loads and the two inverters co-operating to supply grid-tie loads.
March 6, 20197 yr On 2019/02/27 at 12:25 PM, SheldonB said: To Use solar to power all of my electricity requirements in the daytime (+-45Kwh) to reduce my electricity bill which is currently around R5000/month I live on a plot, and my consumption was more or less the same ... sitting at around 50-60kw a day. my avg bill was around 4-6k p/m. I made some subtle changes... 1 geyser was replaced with a gas geyser.. the other i changed the element so i can power it from solar during the day. I changed all the globes ... more than 100 of them with 4W LEDs and i changed my halogen globes with LED 30w globes. Pressure pump ... i added it to a timer.. only runs from 8am to 8pm... every time you flush your toilet or wash hands the pump goes on... one does not really need it outside those hours. My bill this month was +-R500 (excl. connection fee of R125). Total bill was under R700. I have three phase power, so i went for the following: 3x Multiplus II MPPT 250/100 Canadian Solar 275W x 18 3x US200b Pylons VenusXG You will notice that it will never produce the 50-60kw I initially required, but i am 90% off-grid and i have gone 2 weeks straight without mains (I really pushed it). Small things make a difference, like only adding as much water to the kettle as is needed for the 2 cups of coffee you are making. Get a blanket for your geyser... there are plenty tips out there, but i can almost guarantee you, once you are on solar you will notice a significant drop in electricity usage as you are a lot more aware of it. It becomes a pain in the ass actually... every time i walk past my VenusGX I remember to switch off unnecessary lights in the house, i switch off fans that is not used, and i check the lounge to see if someone is actually there using the aircon. I am sure if i was this energy aware before solar i could have easily saved 30-40% of my bill. All the above considered ... from around 11:30 am my PV is underutilized and my batteries are full and geyser is hot. If i properly plan usage i can make sure i get the most of the system throughout the day when there is solar power available. Edited March 6, 20197 yr by stoic
March 8, 20197 yr Author Hi Stoic, thanks for the feedback. I am currently looking at installing the following on further review: 1xVictron Multiplus 2 48/5000 inverter 1x Victron Smartsolar MPPT 150/85-TR 15x Canadian Solar panels 330w or (12 x 400w Canadian solar - This however works out more expensive per watt i thought it would be cheaper?) 1x Venux GX smartcontroller Best price i have so far for the 300w panels is R1700 (excl) and for the 400W R2765 (excl) , so in terms of this 15x330 (4950 watts at R25500 which is equal to R5.1/watt) alternatively 12x400w (4800 watts total at R33184 which is equal to R6.9/watt) So in terms of the above would anyone recommend something different. In additon a few questions Would one recommend going for the 400w panels or the 330w panels i see the 400w panel have a higher efficiency, VMP,IMP etc however i am not sure what that actually means thou? The price is higher however are there other advantages going with the 400W panels? Should i get a larger MPPT if so which one? Whats the difference between the smartsolar MMPT150/85 r and the bluesolar MMPT 150/85 ?
March 8, 20197 yr 1 hour ago, SheldonB said: Would one recommend going for the 400w panels or the 330w panels i see the 400w panel have a higher efficiency Higher efficiency means you need less space for more power. If space is at a premium, then go for the higher wattage panel. Otherwise take the bang-for-buck route and get the 330W modules. The 400W modules are still too new, they haven't really had time to settle down in price yet. 1 hour ago, SheldonB said: VMP,IMP etc however i am not sure what that actually means thou? The important number for you is the Voc number (voltage open circuit). When you place modules in series, this number multiplied by the number of modules series has to be less than the voltage rating of your MPPT (150V in your case). We worked it out the other day: You can put three modules in series if you live in a place that never see frost. All others have to put no more than two modules in series because these 72-cell modules will exceed 50V per module on very cold days (below -4°C). In short: These numbers are important. You'll have to learn how to understand them. 1 hour ago, SheldonB said: Should i get a larger MPPT if so which one? 15 modules at 330W each, that's around 5kw. At 50V (ish, it makes the math easy, and is a good estimate for a 48V battery) that's 100A. So an 85A controller is too small to put down all the power. It will work, but you will lose some power in the middle of the day. You can go for a 150/100, or even a 250/100 (has an open circuit voltage of 250V... more modules in series!). 1 hour ago, SheldonB said: Whats the difference between the smartsolar MMPT150/85 tr and the bluesolar MMPT 150/85 ? One has MC4 connectors, the other one has screw terminals. Exactly the same thing in all other respects.
September 11, 20196 yr Author Apologies for the late feedback. Rengro i eventually settled on the 400w panels, the price i indicated above i believe was from Mustek at the time. My final solar install consists of the following: Victron MultiPlus II Inverter 48/5000 /70-50 MK3-USB Victron BlueSolar MPPT 250/100TR VE.Direct cable for MPPT VenusGX Carlo Gavazzi with RS485 to USB - 5m 3x 3.5kw Pylontech batteries Canadian solar panel 400w x 12 (3 banks of 4 in array) System i believe is performing well, i am not feeding back to the grid so production is limited to usage during the day.. on average i am generating around 18 - 20kwh / day (Once again dependant on what electrics are on and drawing power as i don't feedback into grid) highest Kw produced in a day over the past 6 months is 25.4 kw on the 24th July. Does the above kw's produced seem in alignment with my setup?
September 11, 20196 yr Sounds about right. 25kWh for July should increase to 35-40kWh in summer, depending on your panel orientation.
September 11, 20196 yr 2 hours ago, SheldonB said: 25.4 kw on the 24th July that is an efficiency of 5.3 kWh/kW in mid winter! I do not even get this in summer. Are your panels on a tracker?
September 11, 20196 yr 3 hours ago, SheldonB said: Apologies for the late feedback. Rengro i eventually settled on the 400w panels, the price i indicated above i believe was from Mustek at the time. My final solar install consists of the following: Victron MultiPlus II Inverter 48/5000 /70-50 MK3-USB Victron BlueSolar MPPT 250/100TR VE.Direct cable for MPPT VenusGX Carlo Gavazzi with RS485 to USB - 5m 3x 3.5kw Pylontech batteries Canadian solar panel 400w x 12 (3 banks of 4 in array) System i believe is performing well, i am not feeding back to the grid so production is limited to usage during the day.. on average i am generating around 18 - 20kwh / day (Once again dependant on what electrics are on and drawing power as i don't feedback into grid) highest Kw produced in a day over the past 6 months is 25.4 kw on the 24th July. Does the above kw's produced seem in alignment with my setup? yep seems on track and its only going to get better in summer.
September 11, 20196 yr 2 hours ago, Fuenkli said: that is an efficiency of 5.3 kWh/kW in mid winter! I do not even get this in summer. Are your panels on a tracker? It was probably just after a cold front passed, with clear skies and cold temperatures.
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