Wetkit

@Jakes, I'm not a supplier, but I hope you do not mind me making a few comments.... I can see that you a bit stuck between a rock and a hard place. You most important decision will be to select a system voltage and stick to it. If you looking to change later on, you would have to replace the invertor Invertors DC voltage is fixed, so can not change from 24V to 48V later on with the same invertor. Your new proposed system is 24V. To get the max out of your 2000W PV, you will need at least an 80Amp controller. 2000W/24V=83A. (The Microcare 80Amp controller works out the cheapest when comparing rand/Amp) You will need some good wiring on your invertor. 5000W/24V=208Amp. If you now go to a 48V system, you will be able to add another 2000W of PV panels later without having to install a new solar controller, but it would also mean you have to double the battery bank, so more battery cost I believe you have to find a tradeoff point, where you happy with what you getting for what you spending. Managing your daytime and nighttime load, might save you more in the longer run. With that I am saying run more PV panels with smaller battries, but use all the power during the day and only use minimal power at night. With a bi-directional invertor, you should be able to charge the battries via the genset. Most gensets have a 12/24V DC output, but it is normally limited to 8Amps. (100w to 200w) When using the genset 230V AC output and running a bi-directional invertor, you should be able to use the full power of the genset to charge the battries. Perhaps you might even look at getting a remote start genset? You can then start the genset automatically when your battries is running low. It does increase the system complexity a bit, but it would enable you to go for a higer system voltage and decrease the battery bank AH capacity. If cost is such an issue, with the above changes, you could even look at using truck battries, but you propably going to have to replace them every 3 to 5 years. You would also put on more hours on the genset this way. There is nothing wrong with Outback, Oasis and MLT, but they extremely expencive. I like Microcare as their prices is good and they based in PE.

Ok, an update on the solar water system. I removed the glass panels from the old flat plate system and spend some hours drilling and pop-riviting loads of saddles. Now the pipes is making good contact with the back plate again. After this I used some NS4 black paint to re-paint the complete unit again. The old black was getting very grey. Putting the glass back was a bit of a mission. The diffrence in temp afterwards was significant. Normally the water felt tepid, but now it is heating up nicely. The vacuum tube system is getting a bit scary. On a nice sunny day the water at the tap is reaching around 75C! Would need to start looking at a cover for it during summer.

RIght, just some feedback. System is running pretty well to date. Avg around 5.5kwh per day on the 2 pumps. Where my water bill used to be over R2k per month, it is now around R200 Also had no effect on electricity, as both pumps is running off solar. As it is working so well, I have now decided to include my pool pump into the system. To do this I have added another 2 x 235W PV panels to the system. Still waiting for my 4.5kW pure sine wave invertor to arrive The EPS unit is ok, but it does not work so well with flurecent lights and lighting that uses ballasts. Also tried running my computer UPS from it. That was a bad moove, as it blew the UPS As the 4.5kW invertor is 48V DC, I would have to re-configure my battries to cater for that. Luckly I have enough battries to do that. Next problem is the new invertor does not have a built-in load relay or charger, so if the battries is low, I need to build my own change-over to mains. I am busy sorting out all these details and will post and update as soon as I have it sorted out.

Hi Jakes, You load list looks a bit light, but lets work with it as is. I would say the 10 x 300W panels and the 5kW invertor does seem fine for your use according to the load list. The 60Amp load controller might be a bit light (60Amp * 48V = 2880W) but it is still within reason, so no problem there. I do think the battries will be your stumbling block. Do not work on a discharge of 50% capacity, as that will destroy your battries very quick. (Look at cycle live VS depth of discharge) Rather work on 20% discharg, so for a 105AH, you should only use 21AH. Also, only 1 day of backup time is very optimistic, if you have 3 days of winter storms, but a genny might sort that problem out. If you going totally off grid, rather look at something like the 2Volt MSolar battries, but yes, they very expencive, but would last you a lifetime if properly cared for. Also include a good battery monitor that can give you AH readings and not just a volt reading. Another plan could be to run a cheap 3kva genset for when you ironing and vacuuming. Would save you more money in the long run. Water - What it the cost these days of a "windpomp"? If there is enough wind to consider a wind turbine, why not use a "windpomp"? I know the electrical borehole pumps is extremely costly, but how they compare to a windpomp, i'm not sure. When going for solar water, vacuum tube is the best IMHO. Good luck and let us know how you getting on

MonoLite.

@leaves, IMHO heatpumps is more energy effcient than a normal geyser, but it still needs electrical power to heat the water. With solar I only need to switch the power on during long cold spells, like we currently have. Then you also need to look at the crazy contracts they force on you with heatpumps. If you do not sign the 5 year service contract, you loose the warrenty on the unit. Then they charge around R600 for the first year service, but after that, they can increase the price as they see fit.

The blue "boxes" is the actual battries.

As with any battery, care needs to be taken and the battery must be understood! Lead crystal is much better than lead acid, for standby aplications, as it would last much longer. Problem is LC needs to be charged slower and longer, as bubbles on the plates would reduce its capacity and lifetime. Charging a LC the same as a LA battery would destroy it very quickly. Correctly looking after your batteries is an art all on its own. LA would stand much more abuse than any other battery.

All geysers is fitted with a Pressure reducing valve, but also another called a T&P valve. Basically it is a Tempreature and Pressure valve, installed after the PRV and on the geyser itself. This valve contains a mixture of wax, which would be pushed out if the internal temp is too high or if the pressure is too high. Unfortunately this T&P valve can only operate once ot twice at the most before it needs replacing. Yes, overheating in summer is something to look at. I can either remove some of the vacuum tubes, or cover them up with some shadecloth. Will get to that one once we hit summer.

Ok, so far all is running ok. I am extremely impressed with the vacuum tubes. Only had to switch on the power to the geyser for a couple of days, like when it is raining for a couple of days. I have to repair my flat plate collector a bit, as the riser pipes is not makeing good contact with the plate at the back. Been thinking to use either saddels or some earth strapping to fix the pipes to the backing plate. Not really looking forward to this as I have to remove the glass.

Just a report back. So far I have done 6kw max in one day. Yesterday when it was a bit cloudy I ran up to 5.5kw for the day. I have the aux relay set on the charge controller as Load Shed and Day/Night switch. Basically it means if the solar panel voltage is lower than the battries, the relay will switch. Also if the battery is below a set voltage, the relay will switch. Only problem I currently have is that the relay is switched repeatedly in a short time, while the charge controller seems unsure of what to do. I will ask Micro Care if they can include a type of timer as it is hell on the load to switch repeatedly.

The law states that any grounding point should measure 1Ohm or less. Probelm is that to measure this, you need specialised equipment. Now, just sticking stuff in the ground might looks like a ground point, but does it measure correctly? The way to do gounding correctly is to make sure you know the type of soil you working wiith. Here where I live, we have just sand, which is a very poor conductor, so we have to put stakes in the ground, some up to 6m deep, to get the correct readings. Sometimes you have to combine multiple stakes to get the reading low enough. Last year we did a project at Nigel where we had to install around 1000m of earth cable around the buildings foundation to get the correct ground resistance. Best would be to talk to your local electrical contractors and find out what they do in your area.

Great plan!!! Was looking at doing something like this myself, but it just worked out too costly. Price looks to be around the R2k mark for a 3kW unit. It opens a lot of doors now, especially where the city councils is full of bull, like in CPT Thanks leaves

Right, so I spent some time on Google and read up a bit on the subject, as it seems to be a bit of an issue. Here is some links for your own benefit, granted they mostly from the US. http://www.homepower.com/articles/solar-electricity/design-installation/ask-experts-grounding-dc-systems http://www.solarpowerworldonline.com/2012/04/installation-practices-keep-your-pv-system-well-grounded/ http://www.nmsu.edu/~tdi/pdf-resources/CC102.pdf http://www.nmsu.edu/~tdi/pdf-resources/CC103.pdf http://www.solarabcs.org/about/publications/reports/systemgrounding/pdfs/SystemGrounding_studyreport.pdf What it really comes down to, is that ALL exposed metal parts of any electrical system, be it AC or DC, needs to be grounded. That is the law. It is also stated, that if your PV voltage is higher than 50V, the positive, or negative, of the PV needs to be grounded. And this is where the probelms start. Go and have a good look at your MPPT, and you will find the negative input and output is common. So when you grounding the negative of the PV side, you in effect grounding the battery negative as well, through the MPPT controller. When we move over to the Invertor, you will find that the older type invertors that have an isolating output transformer, the DC negative is also grounded to the invertor chassis. The newer type transformerless invertors seems not to do this. So, at least ground all the metal parts. What is reccomended as well, is to have the PV ground wire seperate outside the building to an earth spike. Incase of a lightning strike, it will keep the flash outside your building while traveling down the earth wire, and not be a fire risk inside the building.

Yea, the MLT units work the same, but they way more expencive and does not have the MPPT included. With grid-tied invertors, the PV voltage is way higher, around 120V DC for start-up, up to around 500V DC max.

Hi, Not sure if any of you have heard or seen these in action? It is a AEC 3kW unit. Basically it is a Grid Tied invertor with battery backup. It gives me options, as I can use it off grid until it becomes legal to push power back onto the grid. According to the agents the price is very reasonable at around R15 400 ex VAT. Would like to hear your comments on this unit. PowerHouse.pdf

@ BenDL, I think you need to re-look the shematic a bit better. There is two grounding points, one via a surge arrestor and another via a breaker, both of these going to the common DC negative bar. @ leave, I have only seen Positive earths on very old 6V cars. It was believed to help stop the metal rusting. The Yanks might do positive earthing, as you know they do everything in reverse. If you do have a component in your system that have positive grounding, do not ground the negative then. Something will go BANG! The only reason for grounding the DC side, positive or negative, is to allow a safe return path for high static discharges, like with a lightning strike. Would you really like a lightning charge to run through your complete system? Might not look too good afterwards Perhaps an installer could comment on Positive grounding?

Hi Leaves, I think according to wiring regulations it is required. Perhaps somebody who have done commercial installations could give better advice. I would think that it is extremely important to do it in area's where lightning can occur, or if you have high PV panel voltages present. Here is a schamatic I found on-line.

Here is a pick of my internal installation. Showing the battery bank. Sorry about the crappy picks, but the lens on my phone is badly scratched.

Ok, so everything is about 90% up and running. Here is an update to my wiring diagram. Changed the 24V DC wiring so that the invertor runs off the fuses and the Solar controller goes directly to the battries. Seems like neither the solar controller or the invertor likes to run directly from eachother. Also installed a contactor on the 230V input to the invertor, which is controlled via the solar controller. As the solar controller have way more programmable functions than the invertor, it seemed the logical choice. So now my pumps will at least keep running if the sun is low or the battries starts getting low. Also the charger on the invertor is switched off, so when the battries is low and there is no solar power, the loads will then run directly from eskom power. Talking about battries. A good friend of mine managed to score me 8 of these beauties.... They heavy as hell and still manage to keep a charge. now the bad This flipping EPS invertor is supposed to be modivied wave, but in actual fact it is a square wave output. This is now causing my pumps to start overheating after about 2 hours of running. Even my UPS is complaining so I can not even run my computers from the solar either. For now just running the irrigation pumps. At least these is controlled by a PLC so I can now play around with the running times too.

You are a very brave man!!! I do hope you have some type of meter on your house at this moment so you can track and record your consumption accurately. Reason I say this is that 200Ah x 48V is not going to last long on even a 5kw invertor, nevermind a 10kw. @ 2kw load you might be able to get 2hours from the battries before they flat. With what you trying to do, the 6kva MLT might work much better. 1. It can combine invertor and mains output, to give you a peak output of 12kva. 2. With the smart load relay option, you will be able to connect and disconnect certain loads depending on your consumption. So while the microwave is on, the stove and kettel will be disconected. 3. Built-in options for backup generator control. For total off-grid application these functions would be essential. Invertor reliability is directly related to the quality of the capacitors. Once those go, it is not worth it to repair. The cooler you can keep the unit, the longer the battries and the invertor will last.

Clint, you planning to go totally off-grid? I am just trying to think of the logic of the 10kW unit. You can run your stove, geyser and oven from your solar, but why. It is very easy to either bypass them so they do not run from solar at all. With grid-tied you can go as big or small as your solar panels, the unit can only deliver what the PV panels provide, so it is not connected in series with your existing supply.

@Clint, why you looking to go so big with the invertor? Just by doing small stuff you can easily limit your max demand to below 5kw.

Since 1st July I see CPT have now changed some of the terms of pre-paid metering. See here for the latest... http://www.capetown.gov.za/en/electricity/Pages/ElectricityTariffs.aspx Basically you will only recieve the 50 free units if you consume less than 350kWh per month! Also to be on Lifeline tarrif you have to consume less than 450kWh per month AND your property must be valued at less than R300k!!! Pensioners can request Lifeline at least. Normal Domestic have now also shifted to blocks of 0-600kWh and 601kWh and above. Interesting to note is tha Net metering will now rather be known as SSEG customers (Small Scale Energy Generators). Allthough they will be screwing you regarding the units you generate at 1/2 the price I did a quick sum, and at 1500kWh per month, you will save R468 per month by bieng on the SSEG rate and that is without "selling" any power back to the grid. I put "selling" like that, cause at the price they pay you, it is robbery!

As stated above, I did NOT use solar mountings, as they were too expencive. I used P2000 from Cabstrut. It is more often used in the Electrical field, sometimes known as Unistrut. It is used as supports for cable racking systems. It is fully hot dip galvinised, so should last a long time. The straps I used is from the building industry. It is normally used to fix roof trusses to concrete walls. It is about 25mm wide and 1mm thick, with small fixing holes already drilled. I got a 10m roll from Builders Warehouse. Just had to lift 2 tiles up to get to a roof beam, screw the strap down with 2 screws and put the tiles back. Then I put the Unistrut down and used some self-tappers to fix the two together. I hope to have some time over the week-end to start with the wiring and mounting the remaining kit.