3kW Grid Tied Solar PV: Watts and Warts.

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#1249713 2-Mar-2015 18:42

I dont think solar alone would get me thru the winter, and as a result even with storage I would expect to see as more people move off taking summer time power, the winter prices would go up even more and more. End up costing you either way.

Richard rich.ms

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#1249920 2-Mar-2015 22:52

The fairest way of charging for capacity. Record the highest energy usage in a 1/2 hour block during peak times. And then use this as a basis for a "network capacity" charge.

Although another (and probably overall better) method - Make it mandatory for everyone to move onto peak / offpeak usage plans. As this will encourage everyone to "timeshift" their power usage to offpeak times. This will become essential when electric cars become mainstream. As everyone will get home from work, Start cooking, use hot water, Switch on their heaters, As well as recharge their electric cars. And by midnight the batteries in those cars will be close to fully charged. So won't be drawing much current late at night.

Peak / offpeak billing will also reduce carbon emissions alot. As less "peaking" generation provided by fossil fuel power stations will be used. And higher late night demand and less peak demand will mean more profits to the owners of renewable power stations and less profits to the owners of fossil fuel power stations. Which will mean more renewable generation can be built without power prices needing to rise to pay for it.

naggyman

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#1249928 2-Mar-2015 23:06

Aredwood: Make it mandatory for everyone to move onto peak / offpeak usage plans.

Once the smart meter roll out is complete it makes it much easier to do this sort of thing.

Morgan French-Stagg

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#1249941 2-Mar-2015 23:17

Aredwood: The fairest way of charging for capacity. Record the highest energy usage in a 1/2 hour block during peak times. And then use this as a basis for a "network capacity" charge.

This is done by the lines company in the central north island , and is hated with avengence by the locals who see a monthly bill every summer that is charging them for the winter peak load connection capacity throughout the year,,, , the fact that it comes as Seperate bill and not with the retailer's power charges rubs even more salt into the wound...

It would be a big sell to move to this nationally...

k1wi

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#1435088 26-Nov-2015 11:57

Hey Porboynz,

It's now two years since your installation and another winter since your last update. How are things going with your set up?

It seems to be pretty common for people to start out full of gusto with their solar set up, but less common for them to continue with long term updates. I guess that's largely because things get a little cyclical after a 12 month period, but the scientist in me would really appreciate another check in with how things are going!

Have you made any further changes or adaptations? Is this year's production pretty much in line with last years, or has there been a substantial variation year-on-year (climate or hardware related)? Any hardware failures or maintenance requirements?

A non-profit committee I'm on is shortly going to be voting on what will likely be a 30KW array, complete with federal subsidies and state SRECs (it's located in the US, but at a similar corresponding lat), so I'm especially interested in longer term experiences.

Thanks in advance!

richms

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#1435097 26-Nov-2015 12:09

Im about to pull the trigger on a solar city install at home. Paying outright for it not the one where I just buy the power.

Anyway, this is in the terms and conditions.

11. CARBON
.1 We retain the rights to any carbon credits accrued through our providing
Services or Goods to you, whenever they arise during the lifetime of those
Goods.

Which seems odd since I am buying outright. Is this the norm for solar installs? Whats the downside?

Richard rich.ms

SumnerBoy

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#1435108 26-Nov-2015 12:27

I installed 3.12kW of panels a few months after Porboy so haven't quite hit 2 years yet, but so far after 497 days I have generated 5233kWh of electricity at a daily average of 10.53kWh. That is above my estimate (which was 10kWh/day from memory) so I am pretty happy.

Here is an email I sent to some family/friends who were interested, which I wrote after 12 months;

One year since solar installed. Total of 3803kWh solar generation @ just over 10.4kWh / day.

My estimates when doing the calculations prior to installation assumed an average of 10.2kWh / day, so we are doing slightly better.

Here are the comparisons for the last 12 months, against the previous years (all numbers in kWh);

Last year we used 9093 for the whole year and it cost $1785.90
This year we used 9412, which is 319 higher, but it only cost $1097.15 (saving of $688.75)
We generated 3803 via solar
We exported 2071 back to the grid (i.e. credit)
We imported 7680 (i.e. cost)
Which means 1732 of what we generated we used (i.e. during the day)
Shows that we used almost half of what we generated, which is actually pretty good, considering I was trying to export as much as possible prior to the buy-back rates going down. I would guess the next 12 months will be higher as we try to use as much as we can during the day when generating.

But we only imported 7680 this year, compared to 9093 last year, which is a 15% reduction, and doesn't include any of the exported PV we sold back to the grid.

Again, my estimates when doing my calculations last year were;

Estimated usage: 9093 (actual 9412)
Estimated import: 7500 (actual 7680)
Estimated export: 2137 (actual 2071)
As you can see these were pretty accurate. Which means my calculations re. payback were pretty much on the money too - i.e. paid off in 8-9yrs...up until they dropped the rates!
That is now looking like just under 19yrs based on current rates which is far from ideal. But hey, such is life, endless hours of entertainment so far!

E3xtc

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#1435116 26-Nov-2015 12:36

The last comment in your email to family/friends is the telling story aye - I read that as (due to the horrible buy back rates), it is no longer a sensible solution if you are looking for a reasonable ROI.

SumnerBoy

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#1435123 26-Nov-2015 12:40

Yep - unfortunately - with the reduced buy-back rates the payback period drops from 8-9yrs back to 18-19yrs.

I think it depends how you look at it tho, I see this as a bit of a project/hobby and get a lot of enjoyment and satisfaction out of monitoring it all and seeing my sub-$25 power bills coming in during summer. I know in reality it is not saving me any money (for the first 20yrs at least!) but it is like buying anything else - there is an initial outlay and then a period of use/enjoyment - as long as that use/enjoyment is worth it to *you* then the fact it doesn't save you money in the short term is kind of irrelevant...

Well that is my mindset after getting it installed and then seeing the buy back rates get slashed!!

timmmay

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#1435132 26-Nov-2015 12:51

A bit of storage could decrease payback time significantly, if it's not too expensive.

SumnerBoy

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#1435163 26-Nov-2015 12:55

Yep - waiting for that to become available and cost effective. I am currently storing as much as I can in my HWC every day - boosting it to 65 degrees before reverting to export. For example in the last 6 days I have diverted 15.5kWh to my HWC which would have otherwise been import as it heats up over night. The system is working very well, but when I built the house I installed solar evacuated tubes for hot water heating (before the PV) and this also heats the HWC. So on hot days the PV diversion cuts out before 10am as the cylinder has already hit 65.

Without the evacuated tubes the PV diversion would be much more *effective*.

richms

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#1435168 26-Nov-2015 13:00

Im planning on sticking a second set of heaters in the aquariums on a timer with a higher setpoint to move as much of that usage as possible to the daytime. On non cold nights it only loses about 4 degrees when off so might move a kwh or 2 to the solar.

Richard rich.ms

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#1435169 26-Nov-2015 13:01

Check out the PV diverters from openenergymonitor.org. I know of a few guys in NZ using them, and I am using a custom/DIY version of the same principle. Very effective way of diverting excess PV without risking importing if the sun goes behind a cloud or someone fires up the kettle.

k1wi

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#1435176 26-Nov-2015 13:08

For the installation that I'll be running the numbers on the tenders will be for buying outright through an independent installer, not through Solar City or another one of those companies such as Vivent (who have both done a lot of installs around here, but usually leases IIRC).

The primary reason for not using one of those cited installers is that here in Massachusetts SRECs (Solar Renewable Energy Credits) are currently worth US$285 per MWH of production, which is where they make their $$'s. That's Massachusetts though and I don't know if NZ has any CC's for residential installs. If they don't currently have such a scheme for residential installs then it comes down to whether there is likely to be any in future government policy...

MA is somewhat unique in the US sense. It has switched massively toward natural gas for heating & electricity, with coal and nuclear shutting down, but has limited pipeline supply. As a result prices for gas and power are reaching California prices during colder months. So that's driving incentives for solar and wind, despite solar being really inefficient during the winter crunch.

mattwnz

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#1435247 26-Nov-2015 14:26

richms: Im about to pull the trigger on a solar city install at home. Paying outright for it not the one where I just buy the power.

Anyway, this is in the terms and conditions.

11. CARBON
.1 We retain the rights to any carbon credits accrued through our providing
Services or Goods to you, whenever they arise during the lifetime of those
Goods.

Which seems odd since I am buying outright. Is this the norm for solar installs? Whats the downside?

That's an odd clause, if buying outright, unless they are also charging some form of ongoing service to you. I mean what happens if you sell the house, the new owners may not agree to that clause, and want to claim the carbon credit savings themselves. I guess it would have be be a disclosure on your house when selling it

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