Feedback on new solar system

Hi all,

We are installing 16 extra solar panels on our roof and adding battery storage.

The battery is a 1.2KW Lithium Iron Phosphate with 10 years warranty made by Enphase.

The installed cost of the panels and battery is $8888. Does that sound reasonable?

They have suggested that we might need an extra battery in the future - another $2500. They have recommended to monitor use for a few months and then consider adding another.

I would appreciate any feedback on whether we are doing the right thing.

Thanks,

Tony

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Comments

Jason

Welcome to Workshop @TonyJ. I hope that you find it an invaluable source of information and inspiration for your projects. I also hope that Workshop members can assist with some feedback for you.

You mention that you are installing extra panels. How many do you have currently?

Jason

TonyJ

https://www.workshop.bunnings.com.au/discussion/comment/3346#Comment_3346

Sorry, yes we already have six panels which give us 1.5kw. The new panels would be 4.32kw, so we would have nearly 6kw. But the battery is only 1.2kw.

Kev

https://www.workshop.bunnings.com.au/discussion/comment/63924#Comment_63924

Sorry if this is a 'downer' on your green savings....
Always keep in mind the 'power' of the panels is the maximum possible output in perfect conditions. In saying that, I assume your system feeds into the network as well?
So my guess is that the panels will charge your battery, then when it's fully charged, the power will feed into the network, providing you with your feed in value.
When you use your power, it will drain the battery before you start drawing from the network. (never 100% drain)
Have you done the calculations regarding the possible/average daily usage (from previous electricity bills) and calculated what the battery will deliver to you (in terms of savings)
Let's assume a few things:
Your system is 100% efficient;
Your battery is fully charged every day and it's 1.25kW.

This will give you 1.25kW/h of power each evening when you get home (when most people actually use power)
My last bill shows the cost of electrical power is 16.62c per kW/h
Therefore, your battery will be saving you (1.25*16.62=20.8c per day or $75.83 per annum)
I don't know what your battery cost, but do the calcs and then assess it against it's warranty period. (Especially do these calculations on your bigger battery purchase)
After you do that, then do the calcs on the entire system (cost of panels vs feed in tariff vs warranty period)
Currently, your maximum feed in would be 4.62kW/h in perfect conditions. Not knowing the angle of your panels and where you are, assume you will get 8hrs per day at the full production (4.62*8 = 37kW/h, subtract 1.2kW/h = 35.8kW/h @ 16.6c per hour = $5.94 per day)
I did the calculations on my place and it isn't feasible (unless I got in in the first few months when they were offering the 60c per kW/h, 20yrs guaranteed)
Battery storage isn't worth it yet.
Stay with feed in...
Cheers,
Kev

Brad

https://www.workshop.bunnings.com.au/discussion/comment/94501#Comment_94501

As @Kev says a 1.2 battery will give you next to no savings. If you have an isolator switch in case of a power failure you can have some back up off grid power for a while, just how long that would last depends on your usage.

Some light reading for you that will also give further links.

https://www.solarchoice.net.au/blog/ac-vs-dc-solar-battery-storage-explained

AHoy

@TonyJ,

I agree with the previous posters. Batteries are not worth buying yet. They are offered to the market at a premium.

Typically power costs you about 45 cents per kW.

The battery you are buying will store 1.2 kWh which means you can run your fridge+freezer+TV+a couple of lights (1.2kW) for an hour or so from your battery every night, then you’re on mains power again. This means you will save about 55 cents a night using your battery and not mains power.

A stand alone 4.5 kW system should cost you about $4k installed meaning the battery is costing you about $4800.

This means that the battery would take you 4800/.055 = 8727 days or approximately 23 years to pay off. A duration longer than the warranty period.

Having said this, electricity is set to double over the next year and some days will be overcast allowing you to draw from the battery and recharge a couple of times, but that's still not enough to justify the battery.

The sales strategy for batteries is flawed at the moment due to the small size available to the market.

Tesla Powerwall is the best value at $11k and 10kWh and a payoff of around 8 years.

You can always retrospectively add a battery to the installation at a later date.

Hope this is helpful.

Isobel

Very interesting discussion. I really appreciate the numbers shared, although it's a bit disappointing. But I'm still excited about Tesla Powerwall. I want to install solar panels on the roof and a battery or two to store the electricity generated. Hopefully it will be feasible to go off the grid one day. I guess we just need the technology to improve a little more to get the cost down. Is it currently a chicken and egg scenario? If more people were buying the batteries then their price might fall, making for a faster return on investment.

TonyJ

https://www.workshop.bunnings.com.au/discussion/comment/3349#Comment_3349

Thank you. Very helpful. It looks like we rushed in too soon. We will try to cancel the battery purchase.

Kev

https://www.workshop.bunnings.com.au/discussion/comment/63929#Comment_63929

Just to clarify a couple of things, a lot of people don't understand the difference of kW and kW/h (kilowatt and kilowatt hour)

Without going too deep into the theory:

with 240v (AC) if you have a kettle that has a 2400W power requirement (or 10A - 240*10 = 2400 or 2.4k), then if you run it for one hour, it will require 2.4kW/h or 2400W for an hour. Now the kettle will boil long before an hour, usually less than five minutes, but it is a requirement that it has a 2.4kW/h supply and it's accumulative over time. It means, 1000W used for 1hour is 1kW/h - it adds up.

Many kitchen items are 10 Amp items (because of circuit/power requirements)

Toasters, rice cookers, kettles etc are 10A or 2.4kW. This is because of general circuits are rated to 10A. (or are circuits rated to 10A because many items are 2.4kW?) Chicken and egg story 🙂

So, the joys of incandescant lighting vs LED lighting - incandescant is usually 60W or 0.25A (60/240) as opposed to LED lighting which is around 15W (lots of inefficiencies, but still better) is 0.0625A (15/240) for the same light output (called lumens) You can't get away from the power needed for heating the kettle (it's inherent for water) but lighting is becoming more efficient.

The short story is, is if you put a kilo of food into the refrigerator, it will take energy to bring the temperature down to five degrees, the hotter the food is, the more energy it will require - therefore, let it cool on the bench for awhile then put it in the fridge. If you have a lot of food, it will require lots of energy to cool it down.

Install LED lighting, Solar hot water, energy efficient reverse cycle air conditioning (18 degrees in winter (wear a beanie), 23 degrees (wear shorts & singlet) in summer) you will start to maximise your power savings & the environment.

One last note:

It does amuse me when people have 'electric and emission free' vehicles but don't realise that they use the cheapest electricity which is usually coal powered electricity... The emissions are somewhere else unless you choose to purchase 'green energy' at exhorbitant costs.

The whole world is a system, and we need to look at the system as a whole 🙂

No, I'm not a 'greenie' but I'm aware.

Cheers,

Kev

TonyJ

https://www.workshop.bunnings.com.au/discussion/comment/94504#Comment_94504

Thanks again for all the feedback. We were able to cancel and will keep investigating other options.

TonyJ

https://www.workshop.bunnings.com.au/discussion/comment/113659#Comment_113659

We've gone with another supplier and are getting 16 270 watt solar panels. The price is $4700 and the warranty is 90% efficiency after 10 years and 80% after 20 years. Pay back period should be about 5 years with normal usage. This is $1000 less than the other quote we had. We have been given a figure of 71 cents per KW/hr buy back from our electricity retailer.

Jason

https://www.workshop.bunnings.com.au/discussion/comment/124449#Comment_124449

This has been an interesting discussion. Thanks to all contributors.

I have just added a new Workshop poll - Are you considering solar battery storage for your home?

It would be good to keep the discussion going as this is a valuable topic.

Thanks again,

Jason

MartyH

https://www.workshop.bunnings.com.au/discussion/comment/131673#Comment_131673

Interesting comparison here - https://www.solarchoice.net.au/blog/home-solar-battery-storage-worth-it-2017

Kev

https://www.workshop.bunnings.com.au/discussion/comment/124449#Comment_124449

Hi TonyJ,

Wow! 71c/kW/hr.

Who's your electricity retailer? I would love to know. I'm sure there are many others that would also love to know - it would make no sense to store the electricity, best to sell it at that price. (Hell, I'd be tempted to put some fake panels on the roof and just feed the mains straight back into the grid)

The best feed in tariff (FIT) from Solarchoice is shown as 17c/kW/hr (link below)

Definitely get it in writing from the retailer before you sign. (and my suggestion would be to hold on to your STC's as they will become more valuable in the future)

https://www.solarchoice.net.au/blog/which-electricity-retailer-is-giving-the-best-solar-feed-in-tariff/

Cheers,

Kev

BTW

Have you, or the retailer, missed a decimal point? the usual FIT is 6-8c/kW/hr, so a FIT of 7.1c/kW/hr is possible.

10x the usual rate is unbelievable. (and I've always lived by the rule, if it seems too good to be true, it usually is) Never missed yet.

Kev

https://www.workshop.bunnings.com.au/discussion/comment/131674#Comment_131674

Hi MartyH,
Didn't see your post until mine had been posted.
I bounced straight through to the post from my email.
Cheers,
Kev

TonyJ

https://www.workshop.bunnings.com.au/discussion/comment/131674#Comment_131674

Am I reading this wrong @Kev? Appreciate your help.

Kev

https://www.workshop.bunnings.com.au/discussion/comment/136091#Comment_136091

Nope, it seems that your supplier is giving you 71.30c per kWh.

Never, ever seen or heard of a FIT that high - and it states that it doesn't have a fixed term, but does have variable rates - which (because I'm a pessimist) will probably drop to usual FIT rates.

Well done and congratulations - would love to know who the supplier is so myself, and others can also 'cash in' on these rates (to help pay down solar systems)

Cheers,

Kev

https://www.workshop.bunnings.com.au/discussion/comment/131673#Comment_131673

@Jason

No, not considering solar battery storage - can't justify the cost (yet)

Kev

TonyJ

https://www.workshop.bunnings.com.au/discussion/comment/139101#Comment_139101

Great, thanks @Kev. Our power company is Power Direct. We live down on the Mornington Peninsula in Victoria. I'm not sure how we got such a good rate given that their website has the feed in tarif at 5c. I'm not complaining!

Jason

https://www.workshop.bunnings.com.au/discussion/comment/141129#Comment_141129

Two out of three Workshop community members are considering a solar battery storage system for their home according to our latest poll.

Thanks to all those who participated in the poll. Feel free to keep the discussion going by replying below.

Jason

TonyJ

https://www.workshop.bunnings.com.au/discussion/comment/139101#Comment_139101

@Kev (and others)

Thanks again for your help. We got a bill last week with a credit of over $1200! At this rate the panels will be paid off in no time, even if we are reduced to a much lower FIT next year.

SolarSam

https://www.workshop.bunnings.com.au/discussion/comment/141146#Comment_141146

Have just started researching and getting quotes so this was a useful thread for me.

I've reached out to three suppliers in my area via https://www.solarquotes.com.au/ and will let you know how I go and post questions, etc.

Looks like we'll be able to get a maximum of 22 panels to give us about 6.6kw, which should be plenty as we're a family of four with a four bedroom house.

Bit confused by the amount of different panels out there, mostly brands I haven't heard of, but so far the installers seem very helpful.

Henno

https://www.workshop.bunnings.com.au/discussion/comment/113659#Comment_113659

Hi Tony, here's a link to a site that could be worthwhile for you to check out:

https://www.solarquotes.com.au/blog/

Finn Peacock is quite knowledgeable about all things solar and I've been using his advice for over five years now and am on the brink of paying back my investment in my 3kW system I purchased for about $5,000.

All advice he gives is free and backed up by good research.

SolarSam

https://www.workshop.bunnings.com.au/discussion/comment/124637#Comment_124637

@Henno @TonyJ @Kev @MartyH @Brad @AHoy

Thanks again for the comments on this discussion. I am slowly learning.

I've got my first quote for a 3.9Kw system with 13 Trina Honey panels and a Fronius Inverter for $6,600 including the fed govt rebate.

Payback time will be about 8 years. Was hoping for shorter ROI. Seems like the quote is a little high.

Henno

https://www.workshop.bunnings.com.au/discussion/comment/131822#Comment_131822

Sam, whatever you choose, just be content with the fact that you are also contributing to our kids' environment. ROI is important, but not as important as leaving this planet a cleaner place than what the government has in store for us.

The FiT you get is just a drop in the ocean and it is up to you to make the phone call to the energy company of your choice and haggle with them for a decent discount or a fair price.

Half an hour of your time and the cost of a phone call will help minimise the cost of power to your home. Combine this with your solar investment and you have the makings of a great savings for your family and the community at large.

It took me a while to train myself in the wiles of doing things at the correct time of day to take full advantage of solar generation, so it is up to you to do the same. The savings will add up over time. The other thing I had installed is a device which helps monitor the usage and generation of power at my residence. Very helpful over the course of a season and eventually a year. The only thing I can advise you is not to get too obsessive about the whole idea of savings. They will come no matter what.

Good luck with the search and I hope you become one of the lucky ones saving the planet one kilowatt at a time!

Henno

https://www.workshop.bunnings.com.au/discussion/comment/136091#Comment_136091

@TonyJ with this outrageously high FiT you will be paying your system off in THREE YEARS! This is dreamworld for me! At the moment, here in Cronulla, I'm getting a measly 12.5c and this is the HIGHEST I've had it since installing my system.

But I, too, am sceptical about Power Direct being able to give you this value for any real length of time. My suggestion is to turn off every appliance in the house and go on an extended holiday for at least three months.

I am totally jealous of you and hope you can realise the value in this extraordinarily generous deal you seem to have been given.

With the warmer months coming up, get cracking on an appliance usage timetable and enjoy the fruits of your endeavours.

Kermit

https://www.workshop.bunnings.com.au/discussion/comment/139176#Comment_139176

Have we got any Victorian Workshop members now rushing to get solar thanks to the new state solar subsidy?

State Solar Subsidy Announcement.jpg

SolarSam

https://www.workshop.bunnings.com.au/discussion/comment/141187#Comment_141187

I've taken the plunge. Went for the most expensive quote of the three that we got but the outfit seemed the most professional and comprehensive to deal with.

Am getting 17 Trina Honey 305W panels and a Fronius 5kW inverter with installation for just over $7k. Should pay for itself in around 7 years. Looking forward to a hot summer!

Cornishman

https://www.workshop.bunnings.com.au/discussion/comment/94501#Comment_94501

Excellent and very useful analysis. Thanks Kev

stewiesnr

https://www.workshop.bunnings.com.au/discussion/comment/114001#Comment_114001

enjoyed the conversation , solar panels are a very confusing matter, the battery info is good thanks and will wait until they are more efficient.

@Henno what is your monitoring system, is it comprehensive on your panel output and usage , also available at a reasonable cost and setup

val

Hi Tony battery back up is the way to go can I suggest a byo system it's a 2.4 battery and it's expand able like the the battery your looking at both can be connect to off peak power so the worst case your be paying the least charges possible any way good luck cheers 🙂

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