Home Solar and maybe Automation

[Mrclopec]

You’re absolutely right,

CAN, not RS-485. Why did I write that? It was one of those mornings.

I did consider wiring another set of CT’s through a relay, but the question of how to control that relay is one I had too. I also didn’t want to open the possibility of phantom voltage spikes on the graphs when the relay switched state.

 

[NZDubNurd]

I just got a verbal estimate...

We have 3 230V phases @ 63A into the house.

They can set solar up on one with a 17KW/h battery and one that just feeds into the grid.

The grid one can have the Spa on it, and I can automate it t heat from Solar, but when we're is in, using 30A+, it'll pull from the grid. The battery would be enough to charge all day and run all night, plus things like the septic system etc would run off it.

Quote was NZ$45k though... US$27.5K... and it would take 12 years to break even, IF we never paid for power or a grid connection, so more like 20+ years in reality? NZ is phasing out low daily charges, so the daily charge reduces, but the unit cost decreases. My new power plan is NZ$3.50 per day, but the unit rate is about 60% of what I used to pay.

 

[Dana]

Justifying the ROI can be tricky. Although I had my eye on solar back in 2012 ... and monitored that tech as it evolved solar was extremely expensive, PV efficiency was pretty bad and both natural gas and electric were dirt cheap here. In addition, we owed good bit on our home loan at that time and had plenty of other areas to focus on.

In 2017 or so I started replacing broken ICE yard tools with battery electric. The initial was a Stihl trimmer with the 36V AP battery series and that turned into several more AP series battery powered tools because I loved it. Every spring they start and work. I don't need to fix stuff or buy fuel/oil .. and the original dinosaur AP80 battery still works!

Then, when 2020 rolled around we got that used e-golf. I was dead set on charging it from sunshine! Natural gas had gone way up in price but electricity was still cheap here. I have two rates (residential at the house and general at the garage) but they averaged less than 10 cents per kWh back when we got quotes. By the time we had PTO we had two increases and I believe I was nearing 12 cents. That's a significant increase in 7 - 8 months. At present that cost is about 17 cents per kWh and I expect it to continue on this path.

Every time the utility jacks up the price my ROI gets shorter but I was going solar even if it that was closer to 20 years rather than the 12 year estimate at the beginning. It was more of a self sufficiency thing rather than a monetary investment (like eggs and fresh garden harvest).


My advice is to get several quotes in writing. No less than 3 and if they do this all remotely asking for money down or a signature, instead of coming to your home and looking at the site, tell them to get lost.

In addition, base this decision off of household needs. If you have power cuts often make sure that the battery can power all critical needs. Find out of the solar can still produce on battery alone in a grid-down situation. If you have a generator see if that can be worked into the scheme.

Also, don't pull a Dana and purchase a massive system if you have inefficient equipment that's nearing end of life. For instance, switching from resistive hot water tank to a heat pump tank saved us about 3,000 kWh per year in electricity. I could have went with a system that was several kW smaller based on that one upgrade.

 

[Uwe]

Quote was NZ$45k though... US$27.5K...

How big a system? Roof-top or ground-mount? How much of your annual usage will it cover?

NZ is phasing out low daily charges, so the daily charge reduces, but the unit cost decreases. My new power plan is NZ$3.50 per day, but the unit rate is about 60% of what I used to pay.

Payback depends very much on rates, (both import and export) and import rates are bound to increase. The estimated break-even on my system in PA was 18 years, but they got the production estimates wrong. I think their shading analysis was terribly pessimistic (and I told 'em so at the time). In March, that system produced 148% of expectations. April: 132%. May 121%. June: 149%. At this rate, it obviously won't take 18 years. But that's not the point.

It was more of a self sufficiency thing rather than a monetary investment

This is the point, although I think Dana is still missing an important part of that equation since her system won't produce w/o utility power to synch to.

-Uwe-

 

[Dana]

Dana is still missing an important part of that equation since her system won't produce w/o utility power to synch to.

This is true but I'm glad we didn't at the time. Most from that 2018 - 2020 tech era were NMC (Generac, Tesla, LG, etc) and all of the 48V LFP batteries that SMA worked with were still RoW market only. That has changed significantly in the last few years!


String inverters have evolved as well. Sol-Ark didn't even make a 200A pass through at that time but this is the guy I have my eyes on now for the house: https://www.sol-ark.com/residential/15k-whole-home-inverter/

... but that's gotta be in conjunction with a replacement main panel (and a new subpanel) because ours is maxed out. I don't think that will happen this year but the storms sure are getting worse and worse! I spent this morning standing corn back up... and I suppose I should have been smiling (I was not) because we still had power.

 

[Uwe]

@Peter -- Buster inspected and approved!



-Uwe-

 

[RGH0]

Just getting a 6.6kw system installed. 15 Jinko 440W panels and 5KW Sungrow inverter. No batteries as the return on investment does not warrant it and power here is very reliable as we have a hospital down the street so they look after us well as we are on the same distribution circuit.

Total cost of the system is A$3700 with signifcant governement grants and green power credits of over $A2000. Discounted ROI about 25% with power prices at A$0.21 and going up steeply. Feed in tarrif is A$0.06 cents.

Also getting a heat pump HW installed and recently replaced my gas cooktop with an induction top and replaced my gas ducted heating with reverse cycle air con / heating ducted system. My place is 40 years old and all of these systems were orginal and near end of life so it made sense to go fully electric and disconnect gas and eliminate the A$40 per month gas supply charge in addition to the more efficient Heat pump users. Gas prices have skyrocketed here in recent years as the local gas fields are depleting and the fields in the rest of Australia are making big bucks exporting.

PS I find the induction cooktop much more controllable than gas and quicker to heat a pot of water and less likely to burn due to the more even heat distribution on the pot especially at low heat levels.

 

[Uwe]

Total cost of the system is A$3700

That's incredibly cheap. I gather you guys have lax certification standards? Here in the USA if you want to connect something to the grid, it hast to be UL certified. We also have a "Rapid Shut Down" requirement for any roof-mounted solar, meaning you can't just throw DC string up there.

replaced my gas ducted heating with reverse cycle air con / heating ducted system.

In your climate, I can see that. I have gas heating up in PA and won't give it up. I'd need a COP of almost 5 to break even on running costs, and I don't think there's anything short of a very expensive ground-source heat pump that can do that in cold winter weather.

power prices at A$0.21 and going up steeply. Feed in tarrif is A$0.06 cents.

A 3.5:1 ratio between import and export rates seems like a heck of an incentive to have some storage capacity.

-Uwe-

 

[RGH0]

That's incredibly cheap. I gather you guys have lax certification standards? Here in the USA if you want to connect something to the grid, it hast to be UL certified. We also have a "Rapid Shut Down" requirement for any roof-mounted solar, meaning you can't just throw DC string up there.

I dont think our certification standards are much different from the USA. Installation has to be by a qualified electrician certified to work with High Voltage DC and all equipment has to be certified to Australian electrical standards which are simillar to UL standards in most equipment. Dual input string inverters are the most common system design here, cheaper than micro inverters and only loose a little efficiency. Apart from the automatic shutdowns in the inverter itself the other requirement is to have a DC isolator before the inverter, it used to have to be on the roof but this was removed as a requirement due to fires in the isolator when exposed to weather on the roof.

The limit to "as a right"connection to the grid is a 6.6kw system here. You can go above that but it requires signficant approvals bureaucracy and is hard to get. The high penetration of solar with more than 30% of houses having it here is giving the utility companies problems with grid stability due to excess feed back on sunny days in many areas.

In your climate, I can see that. I have gas heating up in PA and won't give it up. I'd need a COP of almost 5 to break even on running costs, and I don't think there's anything short of a very expensive ground-source heat pump that can do that in cold winter weather.


A 3.5:1 ratio between import and export rates seems like a heck of an incentive to have some storage capacity.

-Uwe-

Yes the incentive is there for storage and the A$0.06 feedback rate is Government mandated. But the cost of storage here is around A$1000 per KWh after government incentives so the simple payback is around 10years and the discounted ROI about 2% so better to leave your money in the bank The cost of storage needs to half to make it worthwhile considering and that is maybe 5 plus years away. The number of LIPO battery fires is also a concern though most are due to cheap batteries and control systems in electric bikes and scooters.

 

[davisev5225]

The number of LIPO battery fires is also a concern though most are due to cheap batteries and control systems in electric bikes and scooters.

You shouldn't use LiPo batteries in a system like this anyway. They have a higher risk of fire (as you already pointed out) and a relatively short lifespan due to their limited charge/discharge cycles before internal degradation renders them sub-optimal. The better battery chemistry to use right now is LiFePo, though there are some interesting things happening in the solid state realm that might be good in 5-10 years time.

 

[NZDubNurd]

How big a system? Roof-top or ground-mount? How much of your annual usage will it cover?


Payback depends very much on rates, (both import and export) and import rates are bound to increase. The estimated break-even on my system in PA was 18 years, but they got the production estimates wrong. I think their shading analysis was terribly pessimistic (and I told 'em so at the time). In March, that system produced 148% of expectations. April: 132%. May 121%. June: 149%. At this rate, it obviously won't take 18 years. But that's not the point.

Crap - I can't remember what size he said each setup was now... It might have been a 5kw and an 8kw on the battery phase. But it was roof mount - we have a 25 degree pitched roof, facing the panels directly north (into the sun, from down here! the flat surface is about 60 x 25 feet). He's very happy to come out and do a proper assesment if we are interested - I didn't want to waste his time, at this stage.

I don't know how much of our consumption it will cover at this stage... but it would be a majority....

The biggest flaw here, is the buyback rates are horrible - lucky to be a 1/3 of what we pay, unless we go to a plan that pays more, but also charges a lot more when we use grid power - then buyback is about half of what they charge.

Our useage is typical peak time users, but not for the same things - we have no heating in the house, gas hot water, no electric cars etc.

 

[iichel]

This is my DIY build: pretty straight forward. On a good day i produce about 50-60kwh with 24x 420wP.

Zelf zonnepanelen geplaatst, een ervaring (rijker) - Duurzame energie en installaties - GoT

gathering.tweakers.net

 

[Uwe]

Here's my new Florida system yesterday:



I don't have "Permission To Operate" or a bi-directional meter from the utility company yet, so it's configured for "No Export", meaning it curtails production to match what I can use (the the battery can absorb). There were also some clouds around off-and-on. The little 5 kWh battery did yeoman duty during times when demand exceeded production, with total throughput of approximately two full cycles despite being set to go no lower than 30% SoC. I've got a second battery coming but since it wasn't on the plans that were submitted for the permit, so it won't be installed until the system has been inspected and signed off on.

I do believe it would have produced the entire 77 kWh we consumed yesterday if it had been able to export. And yes, Florida still has 1:1 net metering. The legislature passed a bill to kill it last year, but the Governor vetoed it.

-Uwe-

 

[NEtech]

Here are some pictures of my system.
Production started beginning 2021.

 

[Uwe]

Here are some pictures of my system.

Interesting. I don't think I've ever seen that long a row of panels in landscape orientation.

Tell us the specs please. How many panels, what wattage, what inverter/charger, what batteries?

-Uwe-

 

[NEtech]

BYD B-Box HV 10.2 kWh, LiFePO4
Kostal PLENTICORE plus 10, 3 phase hybrid inverter
27 x Ulica Solar UL-355M-120 (355 W)

 

[Uwe]

Yesterday, December 21st, was the shortest day of the year.

Solar production here in PA was just awful:


I now have a total of 43 405 watt panels here. Why so many? Because there's no place here that doesn't have at least some shading losses. There was some sun off and on, but the 34 panels on the garage and house roofs were covered in snow, so the only ones producing were the nine new ones we added with east-south-east facing mount in November, because I was able to clean the snow from those.

Contrast that with Florida. 28 400 watt panels, ground mount, with no shading losses at all:



Although this system was commissioned in July, I didn't get "Permission to Operate" (which I take as Permission to Export Power back to the grid) until November, so I don't know what it's really capable of in the summer. Still, 52 kWh on the shortest day of the year makes me feel quite optimistic.

-Uwe-

 

[Zenerdiode]

@Peter -- Buster inspected and approved!

View attachment 2627

-Uwe-

‘CAT-Scanned’…