3kW Grid Tied Solar PV: Watts and Warts.

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110 posts

Master Geek
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#1130947 17-Sep-2014 19:32

bfginger:
richms: Thats crazy cheap. The prices I saw at the homeshow were pretty insane still IMO. No chance of a payback.

What kind of prices? I know they're much cheaper in Australia and their cost structure can't be too much different.

I was thinking of getting enough to take a decent chunk out of my 1.2kW baseline load and possibly get some to put some heat into the hot water tank during the day, but it seems that noone has made a programmable thermostat for hotwater yet, so I can use solar power to take it up to the limit of the tank if available before feeding back to the grid but only use the grid power to take it to a minimal amount if there isnt enough solar.

Did you mean something like this?
http://www.enasolar.co.nz/Products/immerSUN

Interesting that Enasolar have rebadged a device of the same name from the UK rather than develop their own. Mind you getting it permitted for Aust/NZ would be no small task and it certainly seems to be the best in market from the research I did. Does anyone have a NZ cost for it yet? I see in the UK it can be had for £384 inc VAT or fully installed UK wide for £545 inc VAT. So that's about NZ$1100 installed. Another benefit is the tight integration with their Enasolar inverters, very nice. Meanwhile I followed the Geekzone approach with a slightly less polished version that works in a similar fashion, the Enasolar unit was not available when I was looking for a solution. Plus I'm a cheapskate and enjoy building this stuff in traditional #8 fashion like Sumnerboy.

***If only I did not know now what I did not know then***

freemark

103 posts

Master Geek
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#1130966 17-Sep-2014 19:51

The number 1 thing is to get some good Modules on your roof (or any suitable spot you have). Know the brand, check out how long the company has been around and how long they will be around. It is unlikely that the (commodity) buy price per kW is going to come down much more (if at all) without a transformational shift in technology. Make the decision at that stage whether your physical conditions require Micro Inverters - if they do..get a good brand. String Inverters are pretty ancillary - no-one knows at this stage how long they are going to last - 5 yr Warranties, 10 year life time, maybe more, but they are the easily replaceable part. There is some pretty cheap stuff out there, limited monitoring, and you need to know how much power you are consistently producing, easily & remotely is ideal. Storage is not cost effective at this stage - if you have particular mission critical requirements you need to be pretty dedicated to the maintenance of Lead Acid - or you have $20k-$50k for a set & forget Li-ion solution. There are plenty of Arthur Daly's out there so buyer beware.

SumnerBoy

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#1137128 25-Sep-2014 09:26

Not sure if anyone is interested but if you have an Enasolar inverter and want to pull the data out of it for processing in other systems, I have written a little python script which polls the various data feeds on the Enasolar inverter web server and spits them out on MQTT topics. I am using it to import the data into my home automation system (openHAB) for graphing and monitoring. Works well. It polls the /meters.xml readings every 5 secs and the /data.xml values every 5 mins. It also automatically converts the HEX values reported by the Enasolar in /data.xml to decimal values.

If anyone is interested I am happy to share the script.

mrdodge

33 posts

Geek
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#1147493 5-Oct-2014 08:18

Hi all,

I have just read this thread and I would like to thank all of you for sharing your experience and data on solar pv. I am building a new home north of Auckland and will be installing of from the get go, so what I have learnt from here has been invaluable. When things get started, I I'll report back with my numbers

Cheers

Porboynz

110 posts

Master Geek
+1 received by user: 47

#1147818 5-Oct-2014 19:10

mrdodge: Hi all,

I have just read this thread and I would like to thank all of you for sharing your experience and data on solar pv. I am building a new home north of Auckland and will be installing of from the get go, so what I have learnt from here has been invaluable. When things get started, I I'll report back with my numbers

Cheers

Welcome to the thread, reading your kind comments prompted me to check how long my panels have been installed. Shock horror its coming up to 1 year of operation on the 14th October, so nearly time to post some annual numbers.

Here are a few to start with, then on the 14th I'll post a full 12 months results.

Import Export Meter readings:
6380kWh Imported
1940kWh Exported

3kW Inverter readings:
12kWh Average daily generation
4300kWh generated during 4024 hours of sunshine (11 hours per day average)

Calculations:
9600kWh per annum average before PV (but also before heat pump and LED lights)
4300kWh generated - 1940kWh exported = 2360kWh used (approx. 6.5kWh per day)
6380kWh Imported + 2360kWh from solar = 8740kWh for the last 12 months

***If only I did not know now what I did not know then***

freemark

103 posts

Master Geek
+1 received by user: 11

#1147972 6-Oct-2014 08:15

Porboynz:
mrdodge: Hi all,

I have just read this thread and I would like to thank all of you for sharing your experience and data on solar pv. I am building a new home north of Auckland and will be installing of from the get go, so what I have learnt from here has been invaluable. When things get started, I I'll report back with my numbers

Cheers

Welcome to the thread, reading your kind comments prompted me to check how long my panels have been installed. Shock horror its coming up to 1 year of operation on the 14th October, so nearly time to post some annual numbers.

Here are a few to start with, then on the 14th I'll post a full 12 months results.

Import Export Meter readings:
6380kWh Imported
1940kWh Exported

3kW Inverter readings:
12kWh Average daily generation
4300kWh generated during 4024 hours of sunshine (11 hours per day average)

Calculations:
9600kWh per annum average before PV (but also before heat pump and LED lights)
4300kWh generated - 1940kWh exported = 2360kWh used (approx. 6.5kWh per day)
6380kWh Imported + 2360kWh from solar = 8740kWh for the last 12 months

That's a great output Porboynz.
What are your system specs & module aspect/angle?
Thanks

Porboynz

110 posts

Master Geek
+1 received by user: 47

#1148610 6-Oct-2014 20:44

I have a very ordinary install, 12 x 250W Renesola panels fixed to North facing garage roof and a 3kW Enasolar single string inverter. The roof angle is about 17 degrees, nowhere near optimum and its a tile roof as well which makes the install a bit harder.

***If only I did not know now what I did not know then***

freemark

103 posts

Master Geek
+1 received by user: 11

#1148730 6-Oct-2014 22:49

Porboynz: I have a very ordinary install, 12 x 250W Renesola panels fixed to North facing garage roof and a 3kW Enasolar single string inverter. The roof angle is about 17 degrees, nowhere near optimum and its a tile roof as well which makes the install a bit harder.

Great, thanks..really post & thread too.
That's an excellent reference output.. 17 degrees gives you around 98% Module efficiency, your figures show the great performance of the Enasolar Inverter - go the Kiwi made :)

For what it's worth..I'm in the Industry. We will never get a 2yr "payback" as someone hopes for here. NZD dropping, Module kW is a USD traded commodity and it makes up around 1/3 of the installed cost of a system. We plug in 3% per annum Electricity price rises when people get excited about payback (does anyone consider ROI on their new $15K kitchen or bathroom?) but I suspect those rises won't continue at that rate.

But PV is well worth it....as you have shown.

VinnieV

6 posts

Wannabe Geek
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#1152440 12-Oct-2014 22:41

Check out https://enlighten.enphaseenergy.com/public_systems - This has a list of all publicly available Enphase systems in NZ and overseas. Makes for interesting reading when there's some systems in your area you can check out. I got my 3KW Enphase system installed a week ago (all microinverters) for 11k - Can't wait till the final electrical check and Import/Export meter installation so I can turn it on! Did plenty of research before committing however ....

Jase2985

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#1152489 13-Oct-2014 05:32

Ive been following this thread for a while now and when we eventually go to renovate we will be putting some solar panels on the roof.

My question is my "north" facing roof faces about 20deg to the east of north (020) and is only small about 7m wide at the guttering) (long narrow section) so you wouldn't be able to fit many pannels on there. but my "west" facing roof 70 degrees to the west of north (290) is huge about 15m wide at the guttering. How is this going to effect how many Kw/H i am able to generate? would a split array be better? ie some on the north facing side and some on the west facing one?

also is the angle of the panels critical? from what ive read its doesn't make a huge difference if they are 20 degrees or 37 degrees or 45degrees, is it worth having them tilted to the optimal angle or just throw in another panel?

Thanks for all the info thus far its been very informative

SumnerBoy

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#1152511 13-Oct-2014 08:11

I am no expert but from what I understand the roof pitch doesn't have a huge bearing on the efficiency of the panels - it is only a few % difference in performance between the optimum angle and significantly 'sub-optimal'. For your situation it might be worth talking to someone about micro-inverters too. These are great when you have more than one roof plane, or the potential for shading of some panels, since with a string inverter if just part of one panel is shaded then it affects the whole array. Whereas with micro-inverters each panel has its own inverter and can therefore be facing different directions without effecting any others. The other benefit is you only have low voltage (240VAC) running across/thru your roof, as opposed to the high voltage DC from a string inverter setup.

Definitely worth speaking to the experts about the different options.

SQLGeek

135 posts

Master Geek
+1 received by user: 32

#1152584 13-Oct-2014 10:29

I have been quoted $17,000 for a 15 panel 4kW system using micro-inverters. Micro-inverters were a good choice as the house has 3-phase power and allows the PVs to be split over each phase. The 3-phase inverters are way too expensive, as was getting 3 x single-phase inverters.

This is a new build in Chch, with the panels going on a flat Butynol roof so the installer has allowed extra for the fittings.

A great thread, thanks to everyone for sharing.

gchiu

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#1152781 13-Oct-2014 12:57

Are these panels going to sit on your roof in racks weighted down, or, are they going to create roof penetrations?

SQLGeek

135 posts

Master Geek
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#1152784 13-Oct-2014 12:59

gchiu: Are these panels going to sit on your roof in racks weighted down, or, are they going to create roof penetrations?

Not 100% sure, the installer is meeting with the builder & roofer in the couple of weeks to sort that out. I'll post some photos once they are in.

Hammerer

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#1152871 13-Oct-2014 14:21

Jase2985: Ive been following this thread for a while now and when we eventually go to renovate we will be putting some solar panels on the roof.

My question is my "north" facing roof faces about 20deg to the east of north (020) and is only small about 7m wide at the guttering) (long narrow section) so you wouldn't be able to fit many pannels on there. but my "west" facing roof 70 degrees to the west of north (290) is huge about 15m wide at the guttering. How is this going to effect how many Kw/H i am able to generate? would a split array be better? ie some on the north facing side and some on the west facing one?

also is the angle of the panels critical? from what ive read its doesn't make a huge difference if they are 20 degrees or 37 degrees or 45degrees, is it worth having them tilted to the optimal angle or just throw in another panel?

Thanks for all the info thus far its been very informative

I'd guess that 20 degree NNE will give you 10-20% more energy than 290 degrees WNW. You can check this for your location using NIWA's Solarview which calculates cumulative available energy per m2 on several different days of the year. Simply input your address and if it find it you'll see what you get north facing then you can input the two scenarios you have and compare the results. You can also see the difference for different panel angles.

NIWA also has a short but useful background article https://www.niwa.co.nz/sites/niwa.co.nz/files/import/attachments/solar.pdf

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