Load Shedding

[34by151]

I have finally started to setup load shedding

To do this im running a bash script in Linux and using the output from this to control an ip based relay
The Webrelay is here http://www.controlbyweb.com/webrelay-quad/

There are also single and dual versions of this available
The Dual is more costly then the quad as it has some extra smarts that are not needed anyway

I could run script on a raspberry pi, but as I have multiple Linux systems on ESX its not needed

In a nutshell the script reads the TEDpro DashData.xml and gets the net watts
If im importing power I shutoff the relays
IF im exporting I start to enable the relays.

I have value for the load represented by each relay
So depending on how much is being exported I turn on one or more of the loads
I also keep track of the time each relay is on and store the daily total

Relay1 runs the pool pump
Relay2 runs the pool hot water pump
Relay3 runs the pool cleaner pump
Relay4 runs the HWS booster

In the case of the pool pump it is limited to run 4 hours per day
Any time missed over the last x days is added to that target runtime

The same is true for the pool Hot water pump. This is for pumping water to the solar collectors.
Im presently adding a date range for when this will operate. As we live the tropics heating the pool is not the issue, cooling is'
So we run it at night 8 months of the year for that reason. The remaining time its run during the day.

I might add we have 20Kw of ac coupled solar, 45kw/h of useable storage in batteries and a backup gen
I can also get the data from the hybrid battery inverter, so I need to add that for night use, lots more to do!!!

Re the solar on a very bad day I generate approx 30Kwh, and it takes about 1/2 to 3/4 of the day to charge the battery banks.
On a good Day I generate about 120Kwh and the battery banks are charged by 10-11am. Once the batteries are charged and the household load is taken are of the hybrid unit will ramp back solar production (unless I add load). My household consumption is around 15Kwh so on a bad day the pool wont be running much. But 90% of the time I have too much power available.
Oh yeah when my Ted is showing Export KW im charging batteries, and using them when importing as im "off grid" using a battery inverter

Cheers
34by151








 






 

[Kevin]

Must be nice to have a surplus of solar power! 

With the whole Internet-of-THings popularity, there are a bunch of options on the market for IP controlled switches, some of the ZWave devices even report the actual watt consumption of the load.

Can you explain more about "pumping water to the solar collectors"?   Active cooling of photovoltaic, or domestic hot water?

[34by151]

To be clear on my setup

I have 3 Aurora PVI-5000 inverters
These have more that 5kw of panels each totaling 20kw of panels

The 3 inverters are AC coupled to a Selectronic SP Pro Go
http://www.selectronic.com.au/sppro/

This controls the AC grid Export/Import, Generator (never needed), Battery and Inverters
Im limited to Exporting 5kw to the grid.
The inverters are lined to and controlled by the Selectronic
They are ramped back so the outputs are never more than the output needed for exporting 5kw + loads + battery charge

Im measuring my net power prior to the selectronic
So as far as the TED knows the grid includes the battery

That's fine from the TED side but switching on the pool slows down the battery charging on bad solar days

The reason I have 20kw of Solar is simple. Its sized for the worst days
On my worst days I produce 8kwh per inverter or 24Kwh
If I exclude the 10 or so really bad days I do a min of 10kw per inverter or 30KWh total
My consumption varies from 22kw in winter to 26 in Summer
So the inverters on the worst days cover my use
BTW a good day is 38kwh per inverter for a total of 114kwh

Ive also go logging in the selectronic and im working on uploading the to pvoutput as well as using the battery SOC in the scripts

The battery setup is relatively new (3 months old). My intention is to disconnect from the grid once ive had 12 months of no imported power

In case your wondering it owes me about $40K Aud

To clarify how the pumps work on my pool
I have 3 pumps

The pool pump is your normal 240v 2kw pump this runs the filter and salt chlorinator
The second pump is for the cleaner its a 240v 1kw pump. I have a polaris 360 which works from a separate pump. Its a pressure unit (rather than suction) that works independent of the filer. So when its full it does not clog up the filter
The third pump is for the solar heating. Its another 240v 1kw pump. It plumbed separate to the filter. Water is drawn from the bottom of the pool though a catcher and then the pump. Water is pumped to a solar collector on the guest house roof before returning to the top of the pool. The pump has its own controller that controls if the the pump is running and the speed. It has a temp sensor on the cold and hot side. In reality its only run as a heater for 2 months of the year (we are in the tropics). It also run in reverse 3 months to cool the pool. This is done running the heater at night rather than in the day. The pool is about 250,000ltr (25*5*2m). The solar collectors are just black 13mm poly tube fitted over the guest house roof. The roof is a 20deg pitch north facing (30m long by 9m Wide) and made of colorbond steel. Each tube runs the length of one side of the the roof then crosses over and does the same. So the area of the solar collector is a bit over 270sqm.
The water comes from the pool via a 40mm PVC pipe. This forms a manifold on one side of the roof. Each poly tube come off this manifold. The tubes exit into an identical manifold at end of the roof. This is duplicated of the other side of the roof before returning to the pool. The guest house roof Apex is only 1m above the pool level so drainback is stopped with a pair loops in the pipes (above the apex height) in the pump house.

As for the HWS its your basic 240v electric system. It has a 315L storage tank. The lower element is connected to the mains (selectronic) via the load shedding relay. The upper element is run on off grid solar. Both elements are 240v 4kw elements with the lower element only need on very day solar days.

The upper element is run from 4 * 250w solar panels via a dedicated controller
See here for the controller http://techluck.com/
Basicly its heating the water via PV solar all the time the suns shines.

Its rare the lower element needs to run, maybe 4 hours per year but that more due to hot water use rather than solar heating
I allow the upper element to heat the water to a max of 80degc
The lower element will stop at 55 degc but wont turn on till the water gets below 45degc

I really did not need to put load shedding on the HWS, more just using the using the 4th relay for something. Although is the PV solar was not on the second element it would get used daily

Hope that covers everything, let me know if you need anymore detail.

Cheers
34by151







 

[34by151]

PS,

Once the battery SOC - 100% the inverter will ramp back to export 5kw to the grid + the load
So the Net figure ted is reading is not will drop quite a bit once the batteries are charged but generally wont go below 5kw till the sun goes down

If we say my load is 2kw the inverters would be ramped back from 15kw to output 7kw  (grid export 5kw + 2kw to cover load)
If my load goes up by 2kw because the pool pump is on my load becomes 4kw so the inverters will be ramped back less to cover the load. The result being the inverters will output 9kw (5kw for grid export + 4kw for loads)
On the Ted side even though a load come on the net power will still be -5kw from the ted (load up by 2kw, generation up by 2kw)
This will continue till the inverters are putting out the max 15kw (full sun)

If the ted is reading net power as a positive figure im using the battery but not necessarily importing power from the grid

Cheers
34by151

[jlsoaz]

[...]I might add we have 20Kw of ac coupled solar, 45kw/h of useable storage in batteries and a backup gen
I can also get the data from the hybrid battery inverter, so I need to add that for night use, lots more to do!!!
[...]

That's quite a setup, and very interesting, thanks for writing out your experiences and points.

[jlsoaz]

The battery setup is relatively new (3 months old). My intention is to disconnect from the grid once ive had 12 months of no imported power

Why disconnect?  Because they decline to pay what they owe or what might be a fair amount?

The batt
In case your wondering it owes me about $40K Aud

To clarify how the pumps work on my pool [...]

Until the last year or so I guess I didn't realize how energy consuming pools are, even with solar hot water it seems.

[34by151]

Why disconnect?  Because they decline to pay what they owe or what might be a fair amount?

The power grid is gov owned.
Pricing is worked backwards. The Gov decides they money they want then they add the operational costs and divide it up to dish out prices
Initially solar had parity prices, then they introduced a bonus to get people to invest in solar. The bonus meant you got paid roughly double for exported power over imported power

As solar increases the load on the grid goes down. Daytime its roughly half in the day compared to 10 years ago
The net effect of solar is the more people export the less the gov makes, so they increase prices

They first started upping prices and reducing export rates
Export rates are now 1/6th of import rates
Then they started knocking people off the bonus. Any account change or solar change means you loose the bonus!!!

Recent changes to pricing have seen them introduce a solar meter charge as well as upping the power rates
What this means is the first 3.8kw/h of export per day is needed to cover the meter charge
That's more than most systems export!!!
So for roughly half of all the solar owners its now costing more to have solar than not have it

In summary, If you have solar you pay a daily fee to allow you to export, imported power rates go up, exported power is 1/6th of the import rate

Now there is talk of introducing a mandatory fee to maintain the grid!!! You would pay this even if you disconnect, some states have done this already

The only way around it was to be off the grid before this starts, so you don't have any account

My setup costs a lot, yes but the payback is roughly 7 years (at current prices)
With load shedding that's gone up to 11 years, so you can see the savings loadshedding has
The reason for the rise is I self consume more, import less. Consumption has not changed just timing of consumption
With the next round of price increases the payback goes down though

To look at it another way
Lets assume I disconnect now and that I need the generator to top up 4 times a year for 4 hours each
A 4kw autostart/auto throttle generator costs $800. 4 hours = 1 tank of gas or $20 or $80 per year
The fee to have the gid (and not use anything) is $935 per year

So I pay $935 per year to draw no power or have a generator for $80 per year
I could buy a new one each year and a run it for $880, less than the grid connection fee

I guess it also must be noted I live on rural property. So we have lost of space
If you are in an urban house Id guess you can only fit 5-8KW of panels on the house
I can fit as many as I need. The panels are fitted to the hose and the shed roofs. If I needed more I can ground mount as well, but I cant see needing more

Until the last year or so I guess I didn't realize how energy consuming pools are, even with solar hot water it seems.

The Pool makes over half my use

Cheers
34by151

[jlsoaz]

thanks for the detailed response, I can certainly see why you'd want to disconnect as soon as possible.

Why disconnect?  Because they decline to pay what they owe or what might be a fair amount?

[...]
In summary, If you have solar you pay a daily fee to allow you to export, imported power rates go up, exported power is 1/6th of the import rate

Now there is talk of introducing a mandatory fee to maintain the grid!!! You would pay this even if you disconnect, some states have done this already

The only way around it was to be off the grid before this starts, so you don't have any account
[...]

Until the last year or so I guess I didn't realize how energy consuming pools are, even with solar hot water it seems.

The Pool makes over half my use

Cheers
34by151