Hotch Botch System?

[colin.timms]

Hi, I am in need of help! Some years ago I was lured into getting a tiny 1.5mw “grid attached” Solar system installed with the promise of halving my energy bill, this worked reasonably well whilst I was getting premium feed in terriff with Government incentives, after about 5 years the incentives ceased. My average energy bill was +- AU$280 per quarter, my energy usage was around 12mwh per day.

I then made investigations into upgrading my system, I was given incorrect advice and had another 2kw put on my roof, creating 3.5kw in total, I was told that this would possibly cover my usage thereby have little or no bill, how wrong they were.

I was dismayed when I got home after the install and found I now had 2 separate systems, 2 separate arrays of 8 panels and 2 separate inverters, this was not clearly explained to me and apparently its due to incompatible panels.

Anyway that was 2 years ago, since then my energy bills have been increasing and now average AU$800 to AU$900 per quarter, I get virtually nothing from my feed in which is totally useless, I live in South Australia and am blessed with ample amounts of sunshine which generates about 9 to 12kwh per day (summer time), (probably more than that as I am only able to monitor the newer system),which is pumped straight into the grid, (wasted), as my family is out at work whilst all this energy goes to waste, oh and my usage has also increased to around 21kwh per day, yes I have upgraded things like Induction Hob, Video Surveillance, Intelligent light switched and so on, which in turn use more energy.

Anyway, I want to do something to reduce my reliance on grid power, after watching your youtube videos which are great and very informative, I was considering using an MPPSolar (GK) 5kva 5000w 48v Solar inverter + 80A MPPT solar charger, max PV input 500v with battery back up and powering my critical systems off it, like, my fridge/freezer, security system, technology in my office, or take over or add to what I already have.

Does anyone have any suggestions? I am capable of building my own system and was even considering incorporating a wind turbine to aid with cloudy days, if you live in South Australia or have been here you will know if there isn’t any sun there sure is wind lol.

Thanks,

 

[Will Prowse]

mWh?? What in the world are you powering, a small village? That is a lot of power!

1.5mw is a solar farm. Can you post pictures of your array? I am trying to wrap my head around this and need to see what you are talking about

 

[PHoganDive]

mWh?? What in the world are you powering, a small village? That is a lot of power!

1.5mw is a solar farm. Can you post pictures of your array? I am trying to wrap my head around this and need to see what you are talking about

Later he states
"I then made investigations into upgrading my system, I was given incorrect advice and had another 2kw put on my roof, creating 3.5kw in total, I was told that this would possibly cover my usage thereby have little or no bill, how wrong they were."
So he added 2Kw to make 3.5Kw total.....he started with 1.5Kw...not Mw.

 

[svetz]

Wind can be great. But, wind turbines don't generally start to generate power unless the wind speed is over 8 mph; and around 12 for meaningful power, so before you invest run some calculation based on your average wind amounts. People will be happy to sell you one, all you might ever get from it is an aggravating noise. Read this before investing: www.solacity.com/small-wind-turbine-truth/

Now, we'd be happy to help if can. But, we've no idea what you've got or what's wrong from your description and worse your numbers don't make sense. What would help is to know the make and model of the solar panels, charge controllers, batteries and inverters. Photos of your setup would help too.

 

[colin.timms]

Hi. Thank you all for your reply. Firstly, yes I notices that I had a slight typo error, when I said "I was lured into getting a tiny 1.5mw “grid attached” Solar system" I actually meant, as PHoganDive said a "1.5Kw" system.

The first system installed was a the 1.5Kw system, I don't know the make of the panels but they are the top row in the picture below.

I know it's hard to see, if I get some time I might get on the roof and try and find out what they are (when it stops raining).
Those first 8 panels (top row) are connected to this,


Getting old now but still works.

The bottom row of panels are connected to this,


There is no batteries on these systems.
Thanks again.

 

[svetz]

Inverter Model numbers! Sweet! That's a great start!
The Sharp has two conduits coming in the bottom? Are both of those coming from the roof? If so, probably two parallel strings of 4 in series? (see What does it mean to have solar panels in parallel and series? )? It's rated for 320V, so it could be 1 string of 8 in series.
The first system was 1.5 kW and 8 panels, so each panel about 180W?
The Sola has a 560V input, so possibly 1 string of 8?
The second system was 2 kW and 8 panels, so each panel about 250W?
No battery, so you're strictly grid-tied.
It would help to know the solar panel make/model numbers.

So, if I understand, your question is how much more solar do I need to get my bill to a reasonable level?

To answer that we need to know:

1. how much power you're actually seeing from your existing 3.5 kW array (if you don't know that we can estimate from your latitude/longitude or nearest city).
2. How many more kWh of solar power do you need per quarter to get your electric bill where you want it? You can calculate that by using your bill knowing the price per kWh from the utility. Your bill should show you how many kWh you consume and what the rate per kWh is.

Another thing for you to check on is whether or not your existing 3.5 kW solar array is actually generating any power or not. It might be simple, your inverters might be generating reports for you. But, you might have to play sherlock holmes to figure this out. For example, what are the displays on the inverters saying. Or, how does your electric consumption compare to before the solar was installed?

 

[colin.timms]

Hi, Firstly, the two conduits only go to the kill switch and I recon each system is 1 string of 8 in series as you mentioned, the no's make sense.
svetz you said "So, if I understand, your question is how much more solar do I need to get my bill to a reasonable level?"

Here is a scan of my last bill to confirm that I am actually generating, I know these won't be true generation levels as I know energy is used in the house before feeding the grid I also include a screen shot from my Solax app, which granted is only one of my solar systems.

It makes me laugh, in the "comparison" chart at the bottom of the bill it states that a household with consumption like mine is 5 people, there is only 2 adults and 1 child in my home. lol


As you can see from my bill my average daily usage is 19.87Kwh and I know it would be impossible to generate that sort of energy to storage but I was considering building another totally separate solar system which in no way connects to my existing equipment or supply but could, as I said, run several key load items, like fridge freezer, security equipment and so on up to the capacity of this new (stand alone) system, which would then not come under local Government restrictions because it would not attach to the existing supply.

 

[b.james]

2 adults and one child. Same here . I have a timer on my hot water heater ,let it run 3 hrs only from 3pm that saves heating it all to boiling and keeping it there all day while you are working. You can do the same for a dedicated circuit for fridge and freezers. I'm making a 1/2 inch irrigation tube water heating coil unit to sit on the roof as per "desertsun02" .Look up his videos.

I used to turn the H/W off and only switch it on when I got home . Same with power for fridge freezer and fishtank etc. Couple of $35 timers will do it for you though with more precise control. Funny enough I just put my wind gen up and its pretty windy here . Scares the heck out of me ,the dogs and the cows. Bloody noisy. Also its voltage output is more suited to 12V systems and I'm going to 48 soon. Not sure how I will make it earn its keep.

 

[svetz]

Hey Colin!

You’re making this easy! Thank you!

daily usage is 19.87Kwh – You didn’t specify a target amount but I’ll show the math so you can adjust as needed. I’ll round to 20.

We don’t know what your 1.5 kW system is doing, but as long as it’s working probably not import since we know you need an additional 20 kWh/d.

Based on the bill, your system is exporting 352/95 = 3.7 kWh per day. For which you received a whopping $44 AUD.
At least it indicates your solar is working. Since you consume power internally we don't know the actual amount from this.

You've got 8 panels on your 2kW array, so those must be 250W panels, and the app shows they're generating 182V @ 8.3 amps which is about 75% power, so that seems pretty good. The Solax app says your generating 5.2 kWh/d, which seems low. That says you're getting about 3.5 hrs of sunlight per day (see update below). I doubt it's soiling since the power looks good. Any shading or reason you know of why the total output per day is so low? Is that bill during the rainy season or something?

So the bill shows you're generating excess power, but why the heck is the bill so high....
Oh… I think I see what’s going on. Can you confirm this? Your system is big enough to export power during the day, to which your power company gives you a minuscule credit. In the morning and evening when you’re using grid power; they’re charging you high rates.

When the sun’s not available you’re still going to consume 20 kw, costing you 20x.5 = $10/d. So, to offset that you’d need to generate enough power at the $.15 price to offset it. So $10/0.15 = 67 kWh/d. For losses, let’s use .8 so 84 kWh/d.

Now we need to know how many hours of usable sunlight you get. I don't want to use that 3.5 hr number calculated above as earlier you said you had abundant sunlight. You didn’t provide a city or latitude/longitude, so I’ll pic Cairns and from the insolation map get 5.5; pretty darn good. Just redo the calculations with your location for better numbers or 3.5 if you think that's right.

Okay, so 84/5.5 = 16 kW. So, adding 16 kW should just about zero out the bill.

So really it’s a case of is it cheaper to produce ~5 times the energy you actually use, or is it cheaper to get a battery and store energy while the sun is up to provide power at night. But that's another question!

 

[svetz]

Just realized the 3.5 hrs sunlight per day might not be bad after all as the bill is for your winter months where the sun is at it's lowest in the sky.

 

[PHoganDive]

Funny enough I just put my wind gen up and its pretty windy here . Scares the heck out of me ,the dogs and the cows. Bloody noisy. Also its voltage output is more suited to 12V systems and I'm going to 48 soon. Not sure how I will make it earn its keep.

Something like this, maybe?

Amazon.com: SMAKN Waterproof DC/DC Converter 12V (10-30V) Step UP to 48V/4A 192W Power Supply Module: Home Audio & Theater

Buy SMAKN Waterproof DC/DC Converter 12V (10-30V) Step UP to 48V/4A 192W Power Supply Module: Power Converters - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

 

[colin.timms]

Hi svetz, the bill is for the first half of our winter months so generation is going to be low, also on the Solax app we are still in winter.
I live in Adelaide so according to the map 5.5 is about right.
I think the reason the bill is so high is that like I said, we are out at work during the day whilst energy going into the grid (wasted) and then at night we draw from the grid, so it makes sense to me that I need a battery system, but my only problem is I can't tie it into the existing system due to Government restrictions, I am not a registered electrician.

 

[svetz]

Let us know if you have more questions! Happy to help if I can.

 

[svetz]

Just thinking out loud here..... The government won't let YOU hook it up, could you hire an electrician to just hook an ATS? Something like what's below? Then you could do the rest.

That way you'd always be on battery power until it ran out, and then you'd be on the grid. This would also allow you to add batteries and panels over time and every battery you added would slowly decrease your power bill (although, check the discussion on adding incremental batteries). The batteries would fully recharge whenever sun was available.

​

From your bill your using ~23.7 kWh/d. Not sure how representational that is as you might have the heat on. But assuming it is here are some calculations.... I'll use the lead acid round-trip efficiency as .88; but if you go lithium bump it to .96 (with a cycle per day Lithium is going to be better).

Option 1 - All at once
Let's start with enough battery to handle one full day and enough solar to charge it up. If it's cloudy, that's life you'll go with the grid.

Battery power needed = power needed/eff = 23.7/.88 = 27 kWh/d
Solar power needed = battery power needed / eff = 31 kW/d; at 5.5 hr/d insolation / .8 losses = 7 kW array.
You have 3.5 kW, but it's mismatched panels. Let's abandon the 1.5 kW array for these calculation and assume you can get 28 more of those 250 watt panels.

25% per year for 4 years

Year 1
Get the first 4 kW inverter/charger (if you need split phase you'd need to install both in year 1)
Install first 48V Battery String = 27 / 4 = 6.75 kW
install first Solar power string using the existing 8 250W panels
Install the first MPPT, put the Solax up for sale

Year 2
Install 2nd 48V Battery String = 27 / 4 = 6.75 kW
install 2nd Solar power string = 28/4 = 7 panels

Year 3
Install the 2nd 4 kW inverter/charger
Install 3rd 48V Battery String = 27 / 4 = 6.75 kW
install 3rd Solar power needed 7 panels
Install the 2nd MPPT

Year 4 - Energy independence achieved (except clouds and rainy days)
Install 4th 48V Battery String = 27 / 4 = 6.75 kW
install 4th Solar power needed = add final 6 panels and reset to 4 strings of 7.