3kW Grid Tied Solar PV: Watts and Warts.

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#1086805 10-Jul-2014 22:44

SumnerBoy: I have always considered this a risk of installing solar. There is no guarantee our buyback rates will remain the same, and there is every likelihood they will decrease as more solar getting installed. That is why devices like the MK2 PV Router are so clever, and necessary, in my (and many others) opinions. Robin has just started a discussion on the Open Energy Monitor forums about enhancing the logic of the PV router so that you can dump energy to non-resistive loads - i.e. something like a dishwasher or washing machine. This is where things start to get more complicated but the tools are in place now so hopefully these clever chaps can come up with something even more useful.

wouldn't it be cleverer to just set it up to initialise the dishwasher/washing machine directly and just keep topping the battery load used by doing so? I.E i set p the dishwash/washing machine(s) before heading out and once the output reaches a certain point (or the batteries are topped up) the non inductive load is initialised and uses the 'excess' power created?

Think 'connected home' and add 'smarts' :D

SumnerBoy

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#1086807 10-Jul-2014 22:48

Exactly...;)

PhantomNVD

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#1086828 10-Jul-2014 23:12

SumnerBoy: I am getting a 3.12kW system installed next week. The all inclusive price was $10,500 which included the Ensolar inverter and 12x265kW panels. The only extra (I believe) is the meter changeover fee of $85. Was pretty happy with that price, but I am sure in 6 months it will be less again...

mind saying who did your install please? (PM me if you think you'd rather?)

k1wi

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#1087597 12-Jul-2014 03:02

Porboynz: The panels are on a concrete tile roof which is more expensive to fit, but prices have dropped again since then. Such is the burden of the early adopter, but I am not complaining, it's been great fun.

Yeah, I think the cost of deflating prices (and increasing efficiency) is often overlooked by many people weighing up the economics of solar. It's good you're cognitive of it. In your case of course it has been more than offset by the enjoyment of the system (in much the same way as people by computers even though they will be better and cheaper tomorrow).

Until PV prices stop falling so sharply, the best *money* strategy for those without special circumstances (such as no grid connect etc) would be to put the money in the bank/invest it and gain not only the interest on the principle, but also the additional 'bonus' associated with the falling prices. It's also why consumption monitoring (as your promote) and investing in power efficiency should always come first.

That all said however, the world is full of many more factors than just pure $$. So when people factor in the non-monetary benefits it often makes 'economic' sense.

p.s. How has production been lately? Does your software enable you to show production over the whole year? I can't remember if it does or not.

Porboynz

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#1088841 14-Jul-2014 19:31

p.s. How has production been lately? Does your software enable you to show production over the whole year? I can't remember if it does or not.

Indeed both the Enasolar Inverter and the Owl Intuition software have reporting functions. Here are a set of screenshots from the Enasolar Inverter showing the seasonal variance in output.

Last Week

Last Month

Last Quarter

And finally, Last Year. You can see the trend is still heading down, hoping it will level out and climb back soon.

gchiu

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#1100238 1-Aug-2014 18:09

Just had a quote from a supplier for a 3kW array, and that was for $10,995. And this is for 12 Canadian Solar panels, and a Samil SR3000TL inverter. The sales guy said they had had problems with Enasolar inverters so were switching. I've asked for details which have not come back.

Both inverters I think come with 5 year warranties and embedded web servers.

The system price seems to be a little high from what I can tell even with the cheaper inverter.

I have a flat roof so will need tilt up frames.

Does anyone do frames that one can adjust on a seasonal basis to get the best inclination to the sun?
Or is it best to go for a winter inclination of 26 degrees from the vertical?

Porboynz

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#1102020 4-Aug-2014 19:56

The price does seem to be about $1000 more than expectations, a second or 3rd quote will qualify this. I would think that adjustable frames could be easily sorted for a flat roof, then you could have a summer setting and a winter setting. Something like an old fashioned reclining sun chair comes to mind, it would need to be secure but there are all sorts of marine toggle bolts to achieve this.

gchiu

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#1102044 4-Aug-2014 20:17

Any suggestions on who to get the other quotes from in the Wgton region?

I've got a metal seamed roof so it looks like I can fix any frames without the need for any roof penetrations using S-5! clamps.

SumnerBoy

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#1113388 22-Aug-2014 11:22

For anyone that is interested I have recently started playing around with EmonCMS from the Open Energy Monitor project (www.openenergymonitor.org). These guys are doing some pretty clever stuff and the energy monitoring tools in EmonCMS are very slick.

By using just two CT current monitors and their EmonTX Arduino shield sitting on an old Uno I had lying around I am able to produce the following dashboard. The two CTs are measuring the power coming out of my Enasolar inverter, and the net power being imported/exported from/to the grid - this value is reported as -ve for exports, and +ve for imports.

Using these two values I can configure EmonCMS to display all the information below - i.e. current (and daily total) PV generation, house usage, plus import and export. This is very handy for monitoring how much of my PV generation is being used during the day and how much I am actually exporting. I have some rules in my home automation software (www.openhab.org) which does cost calculations using the day/night/export tariffs I am on for Meridian and shows me the running total for how much the days energy use has cost me. This starts off increasing as I am importing from midnight, but then starts reducing on a sunny day as I begin exporting. Then at night once the sun goes down the number starts going up again. Very interesting to see this net cost change during the day!

There are all sorts of other visualisations you can do with EmonCMS. Happy to answer any questions anyone might have. I think this open source software is a wonderful tool for anyone with solar PV.

SumnerBoy

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#1113393 22-Aug-2014 11:27

And for reference, here is the page in openHAB showing the various energy readings and the cost calculations...

vccmzf

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#1114056 23-Aug-2014 13:21

My wife arranged for a chap to come over this morning and talk us through it, so without any time to research I came away from his visit with the following insights, please let me know if I'm on the right track or if you think 'Im wrong.

Based on our usage, for our family home with four kids (and lots of laundry!) He recommended a 1Kw set up, essentially four solar panels, that he predicts will produce for us around 40% of our power needs in summer and 20% in winter(not exactly what he said but tried to interpret through the sales speak)
Panels and install would cost $8300 + $700 extra as our roof is decromastic and requires more work, however, and somewhat curiously I thought, we can get a $1000 discount if we agree to hang their sign on the telephone pole at the end of our driveway for 10 weeks, so $8000 including GST install, including the gateway monitor "thrown in for free"

We usually spend about $200p/m summer $280p/m winter so roughly $2900 per year on power so at 30% we are talking around $1000 saving per year, meaning after roughly 8years we will be in profit, all the panels etc come with 25 year warranty.Which all sounds like a good deal.

So my questions are:
-I read the big thing is the Inverter this company are selling MicroReplus by ReneSola, does anyone know anything about these?
-And importantly what kind of savings have you seen? My wifes at home so managing the power use during the day as it generates should be easy enough to do.
-Im not reading a whole lot into the sell back to the grid aspect as I think we will use all the power it generates ourselves, possibly in summer we might make a little back but that appears to be around $1 dollar a day if we were to sell 100% of the power it creates with the 1Kw 4 panel solution we are looking at

I'll have a read through this thread and I'm sure I'm bound to learn as I go but would appreciate anyones input, thanks in advance :-)

gchiu

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#1114122 23-Aug-2014 15:43

$8k for 1kW sounds expensive when I compare to the quote I received ( which I think was expensive ) of $11k for 3kW.
I believe $10k is average for a 3kW array installed.
I'm curious as to what your average power consumption is. Mine is a lot more than yours. But our house is poorly insulated being a working man's cottage from the 1920s.

Also, I believe the 25 year warranty is manufacturer's warranty so better to use a brand name.

Niel

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#1114158 23-Aug-2014 17:25

I believe at work we pay about $1 per W for large panels, so going from 1kW to 3kW is about $2k difference in panel cost and not that much extra work to install more panel. The electronics in a controller does not cost much more to handle 3kW than to handle 1kW (about 12A vs 4A at 240V). So depending on their business model and the quality of the components, sounds like the price is not too bad. Most of these systems seem to have a break-even point of around 8 years. BTW, our power bill with 2 teenagers and a huge amount of laundry tumble dried (including 3 Taekwondo suits 3 times a week) is about the same as user vccmzf.

The energy available from the sun is similar in Summer as in Winter. It is just the angle is different so whatever fixed location you use will not be best for both, and in Winter you have less sunlight.

The key would be to use power when the sun is out. I think a nice feature would be if the hot water cylinder can be powered off the solar panels (does not even have to be regulated, its a resistive element) to reheat water during the day and then at night switch the hot water cylinder to mains power. Just need to work out what to do with the extra power when the cylinder is on temperature, but maybe just waste it as you save heaps in setup cost by not having to tie into the grid or run batteries or generate regulated 240V 50Hz. Or charge batteries when the water is on temperature, and at night use the battery power.

You can never have enough Volvos!

Porboynz

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#1114172 23-Aug-2014 18:36

vccmzf: My wife arranged for a chap to come over this morning and talk us through it, so without any time to research I came away from his visit with the following insights, please let me know if I'm on the right track or if you think 'Im wrong.

Based on our usage, for our family home with four kids (and lots of laundry!) He recommended a 1Kw set up, essentially four solar panels, that he predicts will produce for us around 40% of our power needs in summer and 20% in winter(not exactly what he said but tried to interpret through the sales speak)
Panels and install would cost $8300 + $700 extra as our roof is decromastic and requires more work, however, and somewhat curiously I thought, we can get a $1000 discount if we agree to hang their sign on the telephone pole at the end of our driveway for 10 weeks, so $8000 including GST install, including the gateway monitor "thrown in for free"

We usually spend about $200p/m summer $280p/m winter so roughly $2900 per year on power so at 30% we are talking around $1000 saving per year, meaning after roughly 8years we will be in profit, all the panels etc come with 25 year warranty.Which all sounds like a good deal.

So my questions are:
-I read the big thing is the Inverter this company are selling MicroReplus by ReneSola, does anyone know anything about these?
-And importantly what kind of savings have you seen? My wifes at home so managing the power use during the day as it generates should be easy enough to do.
-Im not reading a whole lot into the sell back to the grid aspect as I think we will use all the power it generates ourselves, possibly in summer we might make a little back but that appears to be around $1 dollar a day if we were to sell 100% of the power it creates with the 1Kw 4 panel solution we are looking at

I'll have a read through this thread and I'm sure I'm bound to learn as I go but would appreciate anyones input, thanks in advance :-)

The answers will come if you read through the thread. The key IMO is to really understand your base load consumption. If you are spending $200/m in summer then that's about 600kWh when you take off the daily supply charge at say $1.80/day. If your proposed 1kWh panels were to generate a full 1kW for 8 hours a day (which they certainly will not, even in summer) then that's 8kwh at $0.25 per kWh saved, $2/day or $60/m which is close to the sales mans 40%. Work back from there to produce your own ROI. If you save $2/day that's going to take 11 years to payback assuming you have access to free money (no interest on borrowed funds or loss of interest on money you have saved in a bank)

I think a 2kW - 3kW array is going to have a better ROI. I have 3kW of panels on the roof, not at anywhere near optimum angle for winter admittedly but even today which was just beautiful they generated just 15kWh.

PhantomNVD

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#1114823 24-Aug-2014 22:05

A fairly recent review of solar efficiency in NZ, though perhaps a little optimistic on the output of the panels?

http://www.greenideas.co.nz/buyer's-guides/product-guides/solar's-bright-future

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