Solar Power Thread

Power went off at 2pm in Obz today, so I considered that a good time to redo the wiring.
It now goes something like:

Eskom @ Front of house -> back of house -> SISO Switch -> Battery Inverters AC In
Battery Inverter AC Out -> PV Grid Tied Inverter + House Mini Grid
Disconnected House Mini Grid from Eskom at the DB side.


So far, almost everything works as it should, except for the BI -> PV GTI communication.
Which means that if Eskom off, the house stays on, but
Unfortunately the settings for the Battery Inverter to tell the PV inverter to reduce output didn't work so well, so I need to read more on that. The battery inverters also whined about the solar hot water heater circuit being on (too much load), so have turned that off for now. It can probably get shifted to the AC2 out on the inverter at some point.
 
With all these power outages and load shedding, 12 hours long yesterday, I decided to start looking at extending my current backup power system to go partly off the grid.

My current set up consists of a battery bank and a Bi-Directional inverter that powers most of the house except heavy duty loads which are on a separate circuit.

I'm looking at getting a 2400W+ solar array and using something like the BlueSolar MPPT 150/85 as a charge controller. This will then charge the battery bank.

Concerning solar panels I'm looking at getting panels that are about 235-270w. It is a bit tricky to match the array size to be exactly 2400W so it will probably go a bit over. I will probably get 12 panels for now and if CityPower(Joburg) allows feeding back into the grid I might expand.

What panels can be recommended? What R/Watt is a good price etc.? Also how should one arrange the panels on the roof when looking at the picture? Should they all face the same direction or must I split them to face different directions?



HomeRoof.jpg
 
I'd Stick them all north facing.
Any reason why you don't get 300W panels, would make life easier.

8 Panels @ 36V/8.3A (300W) will work fine with that inverter. Pricing for the bluesolar 150/85 will probably be in the 7500+vat range (had a quote on some last week) when I got my other stuff.

Slightly offtopic - Less happy with the Victron inverters I bought, than I liked, as they run rather hot; they're heating up the room they're in a noticeable amount. The grid tied inverter I have runs cool in comparison.
They're still hot at night, which is slightly troubling, as all they should be doing is passthru, and the odd float charge on the batteries, and that shouldn't make things run hot imho.
I don't like hot equipment, it makes for much shorter lifetimes., and unlike my grid tied inverter which has a 10 year warranty extendable to 15 years, they only have a 2 year warranty.
 
Last edited:
@ oober
Please make sure you keep your battery bank voltage in mind when calculating the size of the MPPT.
@2400W you will need a 100A unit for a 24V battery, but only a 50A unit if you running 48V.
The relation betwwen the solar PV voltage and the battery bank voltage is also important.
Most suppliers reccomend 3:1 ratio at the highest, so for 24V batterybank, PV max voltage 72V.
For 48V battries you looking at 144V. Most MPPT's max out at 150V anyway, so you can reduce the PV voltage to say 110V.

Going for the size of PV panel is difficult to calculate, so that is up to you.
My roof is similar to yours, so I also went 50 - 50 on the roof. This way I get more constant power. I am also not exporting, so keeping power constant is good for me.
Expect around R8 per Watt on larger PV panels.
 
@lsheed_cn
No particular reason, I suppose I can go with 300W panels as you pointed out. What panels can be recommended and where to buy? I see wetkit is suggesting panels for R8/W, wonder of this is excl. VAT?

The 150/85 can support an array of 2400W@24V so I think it should do fine.
Where will I be able to find the bluesolar 150/85 for R8550 incl? I see they sell for about R11k on altenergy but I suppose they are on the expensive side?

What temps are your inverters running? My inverter runs at 35c in the day, hot garage, and 22c at night.

@wetkit I'm leaning towards splitting the array in half as I also would prefer a more constant power.

I plan to first get only 2400W and one MPPT and from there I will see how it works out.
 
Last edited:
oober said:
@lsheed_cn
No particular reason, I suppose I can go with 300W panels as you pointed out. What panels can be recommended and where to buy? I see wetkit is suggesting panels for R8/W, wonder of this is excl. VAT?

The 150/85 can support an array of 2400W@24V so I think it should do fine.
Where will I be able to find the bluesolar 150/85 for R8550 incl? I see they sell for about R11k on altenergy but I suppose they are on the expensive side?

What temps are your inverters running? My inverter runs at 35c in the day, hot garage, and 22c at night.

@wetkit I'm leaning towards splitting the array in half as I also would prefer a more constant power.

I plan to first get only 2400W and one MPPT and from there I will see how it works out.
Click to expand...

+1 for suppliers if I can get things at those prices it would make life much simpler.
 
@Isheed_cn

Received a quote for a complete 8kw solar system. Still waiting on more detailed specs. Not sure if the price is competitive. The price of 250ah gel batteries are $300 each.

What would the customs and clearing charges be should I go ahead. Looking at adding 15 batteries and a charge controller.
 

Attachments

  • wp_ss_20141202_0001.jpg
    wp_ss_20141202_0001.jpg
    91.6 KB · Views: 365
The inverter in the quote is an 8kw Growatt inverter. From the reviews on the net it seems to be one of the better Chinese brands to get.

Just need some feedback if the above system is value for money and what the potential additional cost might be for shipping, customs and clearing.
 
From the Growatt technical sheet.
 

Attachments

  • wp_ss_20141202_0002.jpg
    wp_ss_20141202_0002.jpg
    28.9 KB · Views: 357
I have the 10K UE 3 phase model, works rather well. Cool to the touch, and only makes noise at daybreak and sunset (when its trying to invert at too low a voltage).

Growatt has done the NERSA certification for their inverters, so they're "legal" to use in SA too.

Ask them to give you DDU pricing (delivery duty unpaid), then you just need to pay duties, and they handle the clearance etc.
Clearance pricing in .ZA is extortionate, and they'll probably have better pricing.
Duties on panels, inverters are 0%, you will need to pay vat on the price @ 14%.

I'll be shipping a container of panels and other stuff over in late Jan, headed back to Shanghai at the moment in fact!
 
Let us know if there is a few extra panels in the container available for a low low price to the MyBB ppl :D
 
Thanks. Any space in your container ;)

So last price received was $8500. This excludes batteries. (R95 000 at todays exchange rate)

Looking at local companies I can get 5kva MPPT 48Vdc inverter and 18 poly 235w panels for R58 000. This excludes the mounting system and delivery fee ex joburg to CT from www.thepowerstore.co.za

I might add 20x65ah lead crystal batteries @ R2 500 each. All prices above include vat. Their website has prices ex vat.

I'm not planning to go entirely of the grid for now.

Isheed - Any comments on the products on their website. This is a huge investment for me all feedback is appreciated.

Not sure how their 5kva Axpert 60a inverter compares.
 
spiderz said:
Let us know if there is a few extra panels in the container available for a low low price to the MyBB ppl :D
Click to expand...

+1. Maybe if we all pull together we can import some extra panels and save everyone some costs?

I need at least 8x300 watt panels and the local prices all seem to be at +-R11/Watt incl. VAT. If I can get them for R8/Watt it's a R7200 saving!

Ohh wait, I see the power store have 300W panels for R2,846 or about R9.50/Watt or is this ex VAT? Ok nvm. Its ex VAT.
panel...

Which brings me to the question how much does imported panels work out to in the end?
 
Last edited:
Remember a 250Ah battery weighs in at about 100kg, so 15 will be around 1500kg!!

Look, importing stuff directly might save you a couple of bucks, but what about local support if there is a problem?
Who will be installing the system?
Who will issue you with a valid CoC?

Make 200% sure you know what you getting before forking over your hard earned cash!
 
You must log in or register to reply here.
Back
Top
Sign up to the MyBroadband newsletter
X