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Solar power, cost, installation etc etc

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7 hours ago, ComfortablyNumb said:

What have you been running to spend $5K pa on electricity? 

Alex... don’t answer on the forum.......... 🚔👮‍♂️👮‍♀️

Edited by Steno
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On 27/10/2018 at 6:42 AM, ComfortablyNumb said:

Alex - your 11Kw system is producing 9Kw, is that right?

What have you been running to spend $5K pa on electricity?  We spend about $2K (2 people in a 4 bed house).

The 9kW was just what I happened to notice at one moment when I was standing next to the inverter.  How much it producing at any given moment depends on time of day and cloud cover.

Looking at yesterday's data, power output peaked at 9.35kW and total production for the day was 56.6kWh. I wasn't home so not sure about cloud - there must have been some about as the production trace was bouncing up and down a bit. 

QgPDBxX.png

I have 3/4 of the array facing NNE, with 1/4 facing WNW, so it's unlikely to reach a theoretical 11kW peak all that often. But it does mean the power generation curve over the day is slightly wider rather than higher. I've already adjusted the timing of pool pumps a couple of times, indeed that will be a seasonal adjustment to fire them up earlier in summer and later in winter.

We live and work from home.

I have 2 large buildings and 3 air con compressors, one a ducted system. Not usually all on at once, but when it's hot or cold two can be running. That and an older home which while it has roof insulation many elements of the design are 1970s standard when it comes to energy efficiency. Main living areas are cathedral ceilings and large single pane skylights with no way at present to shade them. Two pool pumps. 

It's also likely I'll have a new 3rd building on the property before long.

Edited by Alex Simmons

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16 hours ago, Steno said:

Alex... don’t answer on the forum.......... 🚔👮‍♂️👮‍♀️

Well, he does live in Bello .....

We always stop there for lunch on our way to our Coffs jaunts.  It has a lot more 'character' than Armidale 😉

23 minutes ago, Alex Simmons said:

The 9kW was just what I happened to notice at one moment when I was standing next to the inverter.  How much it producing at any given moment depends on time of day and cloud cover.

Looking at yesterday's data, power output peaked at 9.35kW and total production for the day was 56.6kWh. I wasn't home so not sure about cloud - there must have been some about as the production trace was bouncing up and down a bit. 

QgPDBxX.png

I have 3/4 of the array facing NNE, with 1/4 facing WNW, so it's unlikely to reach a theoretical 11kW peak all that often. But it does mean the power generation curve over the day is slightly wider rather than higher. I've already adjusted the timing of pool pumps a couple of times, indeed that will be a seasonal adjustment to fire them up earlier in summer and later in winter.

We live and work from home.

I have 2 large buildings and 3 air con compressors, one a ducted system. Not usually all on at once, but when it's hot or cold two can be running. That and an older home which while it has roof insulation many elements of the design are 1970s standard when it comes to energy efficiency. Main living areas are cathedral ceilings and large single pane skylights with no way at present to shade them. Two pool pumps. 

It's also likely I'll have a new 3rd building on the property before long.

Makes sense for you to have solar with all that electricity use during the day.  It's a bit borderline for us because we don't use much, and most use is in evenings when we are home.  Insulation/house design is a big issue.  I was amazed at how much warmer/cooler our 2012 built house with modern insulation standards is compared to our old 80's house.  Both brick veneer, but a huge difference in thermal efficiency.

 

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I did my financial projections with an assumption of an average of 60% of our power being supplied by our solar array, which given we are at home during the day I think is reasonably attainable but I won't really know until I have collected data over a longer period.

The higher that number is, the shorter the payback period and the greater the internal rate of return. At 60% it is an excellent investment, certainly way way better than any regular financial instrument can return.

Time (and future bills) will tell.

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3 hours ago, Alex Simmons said:

I did my financial projections with an assumption of an average of 60% of our power being supplied by our solar array, which given we are at home during the day I think is reasonably attainable but I won't really know until I have collected data over a longer period.

The higher that number is, the shorter the payback period and the greater the internal rate of return. At 60% it is an excellent investment, certainly way way better than any regular financial instrument can return.

Time (and future bills) will tell.

Agree.  I analysed the payback for a host of commercial businesses in our region and the payback ranged from 2-7yrs, but even at 7yrs it was a good investment.  Some of these also incurred peak load charges which really hurt (up to 40% of their bill), because they put such a load on the grid.  A few installed in banks of capacitors which smooth the load & saved heaps.

 

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Having a system that tracks all the data makes it pretty cool.

I've worked out all the factors (daily connection fee, grid power charges, off peak hot water circuit, feed in tariff, GST, applicable discounts) to do a like for like comparison.

Bottom line: so far my power bill for the opening 4 days would have been $44.96, but will now be $4.80.
That's one sunny day, two overcast days and one rainy day.

We have a few warm to hot sunny days coming up so will report back after a full week.

 

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6 hours ago, Alex Simmons said:

 

Bottom line: so far my power bill for the opening 4 days would have been $44.96, but will now be $4.80.
That's one sunny day, two overcast days and one rainy day.

 

 

So after 2 years you should be able to buy a new bike

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12 hours ago, Cottoneyes said:

So after 2 years you should be able to buy a new bike

Ha! 

Seriously though, keep in mind the upfront capital investment has to be recovered and financial benefits need to exceed that for alternatives uses of the money*. Which is why my assessment used an IRR approach which factored in the lost opportunity of an investment return for an alternative use of the funds (or in the case for some people, the cost of borrowing money to pay for it).

Obviously I need a full year to have a much more solid assessment of the returns.

For long term projections I also considered long term factors, such as the very gradual decline in performance of the system, the prospects for grid energy prices and so on. Some are relatively easy to predict, others less so.

If anyone is considering a system, I'd be happy to work through some numbers. Of the 3 companies that I had quote for our system, only one provided an assessment of financial benefits. But I considered their model to use some rather optimistic assumptions. So I built my own.

 

* of course some may wish to spend the money because of the less tangible environmental benefits, mostly the reduction in greenhouse gas emissions. I'm assessing from a purely $ perspective since when push comes to shove, this is what will drive most households.

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