Hybrid Solar Part 2: How To Future Proof Your Solar System

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Hybrid Solar Too?

In my previous blog post on hybrid solar systems (aka grid connect with battery backup) I promised to follow up with a post that went into more detail on the costs and give examples of inverter hardware that can be used to make such a beast.

I’ve realised that if I go into the costs and paybacks then this blog post may be longer than War and Peace. So in this post I’ll cover the hardware and I’ll save the financials for next time.

As I said in the previous post, your motivation for spending more on a hybrid solar system will likely be either:

1) You want backup power when the grid goes down.

2) You want to minimise your electricity exports due to a painfully low or non-existent Feed In Tariff in your state.

3) You may want to maximise your electricity exports due to a very generous FIT in your state (Hello Queenslanders!)

4) You may want to “shift” the peaks in your grid electricity usage due to a Time-Of-Use electricity tariff. This would involve charging your batteries at a low tariff and using your battery power + solar at peak times to avoid paying the peak electricity rate.

(And even if number 4 is not relevant to you know, I’d bet my mountain-bike that sooner or later everyone will be forced onto a time-of-use tariff.)

Now, I could go through every possible combination of hardware for every possible combination of the 4 requirements above. But the post would be so long and repetitive that even the hardiest solar geek would probably tune out.

So instead I’ll present for your delectation a system that can be configured to do all the above. Which I would argue is the most future proof solution anyway. Because recent history in NSW has shown us that we can’t trust the State governments to keep their word on Feed In Tariffs and it seems obvious that time-of-use electricity charging (you pay more for your electricity at peak times of the day) will become the norm very soon.

Hardware Required for a future proof, super-duper mega, mega configurable  Hybrid Solar System:

First let’s look at what goes into a standard grid connect system:

1) Solar Panels

2) Inverter

3) Everything else: Wires, Racking, Disconnect Switches, fuses etc.

A Hybrid Solar System needs all the above and more. The extra hardware needed is:

Power management unit (box of electronics)

Inverter that can talk to the power management unit (or is integrated into it)

Bank of Batteries

An example of a “power management unit” that will do the job and has all the configuration options you’ll probably ever need is the 5kW Rich Electric SuperCombi.

Rich Electric SuperCombi

Makes the coffee too?

This sucker can be configured to:

  • Allow you to disconnect fro the grid and still have power.
  • Charge the batteries only when electricity is cheap.
  • Minimise grid power usage when electricity is expensive.
  • Discharge the batteries when electricity is expensive.

And the joy of having such a configurable system is that if, in the future, the government changes the rules you can re-jig your system for maximum profit!

If, for example, the government came to its senses and introduced a “time of use feed in tariff” where you get paid more for exporting energy at peak times, you could configure the SuperCombi to buy the electricity when it is cheap, push it into the batteries and sell the same electricity when it is expensive (ideally along with all your solar power).

To connect the whole caboodle to the grid you would have to combine the SuperCombi with a Grid Tie Inverter from the same manufacturer (e.g. Rich Electric’s SolarWorx GTI). The reason you need to use this particular inverter is that it can talk the same language as the Supercombi so that they can work together and do all the smart stuff listed above.

And don’t forget that you will need at least 200Ah of 48V batteries which will give you 9.6kWh of electricty storage to play with.

Here is how all the bits connect together (at a very high level):

 

A Block diagram of a solar hybrid system

The SuperCombi is the brains of the system and can probably feed the cat too.

 

As you can see, everything goes through the SuperCombi.  To cut a long story very short, this box of electronics has the ability to be programmed to follow any kind of logical rules based on the state of the batteries, solar panels, grid connection, or time of day. It uses this logic to route either the:

  • Solar Power
  • Battery Power
  • or Grid Power

or any combination of the three to either charge the batteries, power the home or export to the grid.

It can also be configured to only power the “essential circuits” in the house if the grid goes down – to extend the time you can run on the battery bank.

Essentially your solar system has been transformed from a rather simple electrical system, to a sophisticated computer controlled power management and battery backup system. This means that if you are looking to install Hybrid Solar, it is essential that your installer/designer has both the “Off Grid” Clean Energy Council Accreditation (so he knows how to handle the batteries), and also has good experience of the hardware being used, as it gets pretty technical pretty quickly, even for a Chartered Electrical Engineer like yours truly.

Next Week: I’ll add up the costs of the solar hybrid system compared to Grid Connect and also crunch some numbers to see what the payback is for the extra expense incurred

 

About Finn Peacock

I'm a Chartered Electrical Engineer, Solar and Energy Efficiency nut, dad, and founder of SolarQuotes.com.au. My last "real job" was working for the CSIRO in their renewable energy division.

Comments

  1. Helen Holmes says:

    THis sounds interesting. Living where we do there are often grid outages – after Yasi we were without power for nine days – so it’s really annoying that our solar power is automatically switched off when the grid goes down and all that potential power is wasted. We’ve asked about a separate ‘standalone’ system but that means having a big bank of batteries sitting there useless most of the time. This system seems to cover all eventualities so I’ll watch with interest. Can this just be slotted in to an existing system (ours is 3Kw)?

    • Yes! This can absolutely be retro fitted to an existing grid connect system. You can use the supercombi, above, alternatively other hardware that will do the job include:

      Victron MultiPlus
      Latronics PVEdge
      SMA Sunny Backup (most expensive option)

      The best way to find an installer for this (currently) niche type of system is to give the manufactures, above, a call and ask them for your closest dealer.

      • Doesn’t the SuperCombi have to be combined with the ( proprietary ) SolarWorx GTI?

        If so you would have to replace your existing GTI…

  2. Wayne Hill says:

    Firstly Finn – Congratualtions on a brilliant website. Wea re going the path of 5kW + in Victoria and your advice & three quotes system has been invaluable
    Here’s another reason to go Hybrid…
    If you live in a bush fire prone area and you want to use electricity to power pumps etc to protect your home you have a power source that is indepdent of powerlines that fail in bush fire conditions. advantages of elctyric pumps might include being ale to leave your house and still run awater pump for much longer than a tank of petrol. Additionally electric pumps are more likley to perform in extreme temperatures ( if properly shielded) where petrol pumps can have “hard to start” & over heating problems when the temp is in the 40s.

    Maybe you could give us an indication of what the hybrid packages might cost to set up for a 5 kW system.

    I’m tempted because I can source good but out of spec/date batteries.

    • Hi Wayne,

      Expect to pay these on top of a standard grid connect system:

      5kW Supercombi: $3,000
      9.6kWh of Batteries: $3,000
      Supercombi Compatible inverter: $1,000 more than a standard inverter
      Extra cost for install due to more specialist knowledge and extra cabling: $1000-2000

      So whereas you can currently get a budget 5kW system for about $10,000, expect the hybrid version to cost closer to $20,000.

      Finn

      • Thanks Finn for the ideas.

        Been sniffing out hybrid systems components, PV systems, battery systems, UPS ( mummy my head is hurting )…

        Does anyone have alternative solutions? I am after something that can charge batteries during off-peak using grid; discharge at any time for feed-in to grid; integrate GTI; have UPS.

        Need to look more at the technicals, but so far…

        The Victron Energy systems are in the lead.

        Victron vs. SuperCombi – you don’t have to buy proprietary grid inverters. You can use your own inverter and buy a Victon Solar Switch for < $1000. Victron system: you can get something called a Solar Switch http://www.victronenergy.com/upload/documents/Brochure%20-%20Solarswitch%20-%20SAL064122020%20-%2002%20-%201103%20-%20EN_web.pdf
        The Victron Energy systems have pretty good application software for monitoring and system control.

        Have bigger capacity units ( more power grunt ) compared to the Rich Electric systems. i.e. don't have to buy multiple lower capacity units.

        Victron is made in Europe, Rich Electric Taiwanese.

        Victron is much more prevalent worldwide, and maybe more competitive buying opportunities?

        Victron has application software that can run in simulation mode so that you can evaluate it.

        SuperCombi is ( suspiciously? ) similar to the Victron MultiPlus. The Rich Electrics (Renergy made – Rich Electric OEM badged it seems) don't as yet have application software available (got email from engineer telling me it is still under development).

        Nedap PowerRouter Solar Battery is all-in one, one-stop-shop. Has PV grid inverter, power backup, battery charger/inverter. Has simple monitoring only via Nedap website (at least for end user it seems). Set and forget – good for most consumers. No separate monitoring and control software for the geek/engineer/control freak? LOL. Up to around $ 9 000 for 5 kVA system, so smaller systems the pricing is quite good.

        HOWEVER, need to look closer – http://forums.whirlpool.net.au/archive/1798415

        Also been ( foolishly- I KNEW that Advanced Diploma in Electrotechnology from TAFE would be useful SOME day! :]) toying with the idea of buying other (read cheaper) components and developing DIY hardware, firmware and software interfaces for monitoring and control.

      • 1. COST VICTRON VS RICH ELECTRIC

        SuperCombis don’t come in 5 kVA so…

        For a 5 kW system you need 2 x SuperCombi, requires 3 x 2 kVA SolarWorx GTIs.

        $ = 2 * $3 000 + 3 * $ 1 500 + shipping
        $ = ~ $ 11 000

        Victron Energy MultiPlus – can use standard GTI, and for around $ 1 000 extra buy a Victron Solar Switch with programmable relays.

        $ = 1 * MultiPlus 5 kVA + 1 * Solar Switch
        $ = ~$4 000 + $825
        $ = ~ $5 000

        PLUS ( OPTIONAL ) GT INVERTER $ 1500 – 3000 ( cheaper available )

        ~$ = $6 500 – $8 000

        OWN EXISTING 5 kVA inverter

        $ = $ 5 000

        You work out the savings…

        Around $3 000 – $ 6 000 for 5 kVA system

        2. BATTERIES
        For lead-acid batteries you need to look at the % discharge levels, and how long you want your batteries to last.

        The thing I am trying to figure out at the moment is whether to buy heaps of lead-acid batteries ( cheap, but need more units ) or LiFePO4 ( more expensive, need less units ).

        For lead-acid if you want a long life ( before you have to buy a new lot ) discharge % should be around 20-30%.

        If that’s true then that means that if you want theoretical nominal 5 kWp ( without all system losses ) you need 20-25 kWp.

        You now need about $ 6 000 in lead-acid batteries… ( based on quick eBay search ).

        3. HELP ME PLEASE

        WITH INFO ON CHARGE/DISCHARGE TIMES FOR SLA AND LiFePO4

        For charge/discharge times for battery banks

        • Apparently with the lead-acid designed for stand-alone systems, these can be discharged down to a lower level, as can those designed for electric forklifts, buggies etc etc.

          LiFePO4 can be charged in around 3 hours vs. lead-acid which take in the order of 10+ hours?

  3. Wayne Hill says:

    Oh and also…
    Looking at your high level diagram it looks like we may be able to go with a standard 5kW approach and then get a Super Combi Power managment system at a later date ( and some batteries)
    Is that a possability?
    regards wayne

  4. Solar Power Guy says:

    I am reading this and i think that this can be really cool thing in order to transform my solar system to that stuff you are writing about.I am waiting your next post.

  5. Hi Finn,

    thank you for all the information and latest updates. its really good to know all this for a novice person.

    would you by chance know any one who does hybrid installation, as in my case i was thinking of getting the normal grid connected system but realized that my house hold would be using electricity most at evening and night . so most of the generated output would go tot eh grid during day and wont make much diff. at evening i would be still using expensive power from electricity company.

    Regards,
    Nilesh

    • Let me know what postcode you live in and I can find your nearest solar company that specialises in Hybrid solar systems. Be prepared to pay at least $10k for it though as it is quite a specialist system with expensive electronics and batteries, as it is not a mass market offering (yet)

  6. unless govt increase the feed in rate to match up or at least 90 of the what retailers are selling, its tough to get huge gain and have never to pay the bills (my avg house hold usage is about 3.5 kwh per day).

    which i doubt govt would do, even after the carbon scheme the prices from retailers would be high. i understand govt can not make every one happy particularly high tax paying energy companies who also pay lot of donations to the political parties for their campaign etc.

    what is your suggestion , should (in my case) i invest couple of grand in solar panel or not.

    Thanks in advance
    Nilesh

    • Hi Nilesh,

      If you are only using 3.5kWh per day (a tiny usage – well done!), you will probably never have another electricity bill again with a 1.5kW solar system (depending on your state and what time of day you use the electricity).

      To see the economics of that investment in about 2 minutes you can use this calculator:

      http://www.solarquotes.com.au/calc3/indexsavings.php

      Hope That Helps,

      Finn

      • Hi Finn,

        Thank you for the repose , I live in NSW, near blacktown. and main usage would be at evening and night ( TV, Microwave etc.) during day apart from Refrigerator nothing is on or stand by.

        Regards,
        Nilesh

  7. Thank you for your advice.

  8. Thanks for the great info! Very thought provoking… I have just provided my details and will be getting 3 quotes for my place in Qld. I thought that there were rules against being off the grid when within a certain distance to the grid? The system you suggest in the article above seems to get around this by being on the grid but also capable of being off the grid if required. It is also interesting the savings that can be made with the supercombi simply using mains power during off peak to charge batteries and then revert to battery power during peak times. This is regardless of the benefits of the solar power. Also, it seems it is able to operate at full efficiency even at high temperatures which will also improve payback times. I will check out more info from supercombi and see if they have any SEQ installers. Thanks again!

  9. Hi Finn,
    Could you please advise if you know whether a “normal” solar installer would have the knowhow to put together a hybrid system or whether I would have to go with a more specialist installer? Also, I am very keen to get in with my solar asap (hoping to commit to an installer within the week!) to ensure I benefit from the 44c feed in tariff that is soon to end in qld. That said, do you think I could get a 4kw system installed switching the inverter they offer with a supercombi with a view to sorting out the rest of the install later (to make a hybrid system)? I just dont want the extra complexity to delay the install and lead to me missing out on the feed in tariff. I look forward to your response as it would assist me greatly! cheers

    Mike

  10. vanessa says:

    Hi Finn,

    Great site thanks. Just wondering which solar companies in Adelaide specialise in these hybrid systems (sounds perfect)? (p/c is 5033). Do you have a rough notion of how much a 1.5kw hybrid system would be? Thanks in advance

  11. Heya Finn…….exactly what I’m looking for! We have been living remotely for two years and completely off grid generating our own electricity. Going back to grid with an impending move = OUCH ! :(. Would really appreciate your advice on an installer for hybrid systems. Post code is NSW 2549. Thank heaps. Kevin.

  12. Finn

    Have read the above with great interest. Can you advise a contact for hybrid system at Qld postcode 4670.

    Thanks

    Trevor

  13. Mandy Rogers says:

    Hi Finn,
    Could you please tell me of a Hybrid installer for Albany, WA 6330? We are connected to the grid but we would have brown outs or black outs at least once a week. Which means no water, freezer full of meat at risk, etc..,.

  14. daniel lee says:

    hi finn

    my postcode is 4218 pls tell me who i should call
    thanks

  15. Hi Finn, I’m in the process of getting quotes from the 3 recommended solar providers in my area, but so far none of them install hybrid systems. I was wondering if you could recommend a provider in the area of postcode 2079 that does specialise in hybrid systems?
    Cheers,
    Nick

  16. Hi I have just purchased my first home and due to working part-time ad studying, my income is limited, With the energy cost skyrocketing and the con job from energy retailers where I buy back my own solar power for far more than they pay me for it, I am interested in a hybrid system to store my solar power that I use myself in peak times particularly and store what is left, with only left overs going to the grid. I would like to use as little energy from the grid as possible, and just use what I am generating in power. I live in 2298 postcode and am interested in suppliers in my area and what the cost could be?

  17. Hi Finn
    I have 10 solar panels at the moment feeding back into the grid ,what i was thinking of doing was getting a separate system and batteries to run things like the TV, dryer and fridge would this be possible ?and roughly how many batteries would i need .
    i live in Perth

    • It is possible but expensive- but I would only run low power devices – not a dryer! How many batteries you need would require a power audit to determine your actual usage.

Trackbacks

  1. […] Part 2 on Hybrid Solar Design here…. About Finn PeacockI'm a Chartered Electrical Engineer, Solar and Energy Efficiency nut, dad, and […]

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  3. […] Peacock has kindly explained the hardware and the costs and payback in two more follow up […]

  4. […] my previous 2 posts I looked at the concept and design of Hybrid Solar […]

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