Enphase just released a video detailing the company’s new grid-agnostic Ensemble system, built around the 8th generation IQ8 microinverter. This is very exciting stuff, particularly for those in areas prone to power outages.
More than 98% of solar PV systems around the world are grid tied. They are required to disconnect from the grid when there is a power failure. They simply can’t create their own grid when the power goes down.
Hybrid systems are starting to gain some traction, particularly as governments provide incentives to encourage the uptake of batteries. However these are still very expensive and are often limited.
Enphase has developed the Ensemble solution to combat this problem. There are five key elements of this solution.
The IQ8 microinverters are the base on which the system is built. They have all the advantages of microinverters but this 8th generation is also grid agnostic; if the grid fails, they will continue to provide power to the home (with sufficient sunlight).
The Encharge Battery is designed to optimize energy generation to save money when tied to the grid and maximize availability during emergency when off-grid capability is enabled.
The Enpower switch seamlessly isolates a home for operation during a blackout.
The IQ Combiner enables real-time connection of a solar system to the cloud with the most efficient, effective and reliable communication protocols. The IQ Combiner ensures the longevity of the warranty for the lifetime of a system and allows the installer and Enphase to troubleshoot if needed to provide the best ROI.
The Enlighten Cloud Software delivers real-time monitoring and insights of solar generation, energy usage, connection to the grid and battery usage.
Manufacturer release dates are usually optimistic but we expect this Ensemble system to be available in Australia in 2020. In the meantime, the IQ range of microinverters will be compatible with the new system so you don’t have to wait to install a system.
So you have a solar system and you’ve heard how great it will be if you add a battery to it. Perhaps the sales company told you your system was battery ready but the prices on batteries aren’t quite there yet. Are we nearly there yet? Let us show you the financials of a battery and you can better decide if they will work for you.
There are different types of hybrid battery systems out there. Some will provide emergency backup when the grid fails and some provide other tangible economic functions but most are there simply to help you use the energy you generate rather than exporting it to the grid. We will focus purely on the latter.
But first, can you even add a battery to a system you bought years ago? It’s not battery ready is it?
Actually, batteries can be added to nearly any solar PV system. They are simply added in parallel with a measuring device put in your switchboard. In most cases, you can add a battery.
We could go on and on about sizing the battery appropriately and how to do that. We will just focus on the economics and leave that for another post.
It is probably easiest to start with the perfect scenario where the battery completes a full charge and discharge cycle in one day. We’ll use a perfect 10kWh battery for our example.
If your solar system has the capacity to completely charge this battery and you use all the energy stored then you avoid paying 10kWh of electricity per day. People pay different rates of electricity so lets assume that it’s 25c/kWh. It looks like the savings are simple:
10kWh / day x 25c/kWh = $2.50 / day
Fortunately however, you were likely to have been paid something for that energy had it just been sent to grid. This varies a bit so we will work on 10c/kWh. Simply sending the solar energy to the grid instead you save:
10kWh / day x 10c/kWh = $1.00 / day
This means, the saving due to the battery is only:
$2.50 – $1.00 = $1.50 / day
This ideal battery will save no more than $550 a year to someone who has a solar system with the capacity to use it effectively. You must remember that this is with an ideal battery being utilised to capacity every single day.
Unfortunately there are days like this, when even a 10kW system only exports 7kWh so wouldn’t get through a complete cycle. The only way to make sure you can charge it every day is to undersize it, in which case you probably wouldn’t notice the savings at all.
Furthermore, even if you produce the extra 10kWh, your charging device might be limited to how much it can handle at one time. For example, if you are producing 6kW but can only charge at 2.5kW, you’ll export 3.5kW. You will lose storage potential if the charging is restrictive.
You will be lucky to get 90% utilisation from the battery if it is well sized to your solar PV system. A battery that is too big could easily be down to 30% utilisation. That brings the savings down to less than $500 a year.
Batteries also have inefficiencies. A lithium battery will typically only return 90-95% of the energy put in to it. That 10kWh battery is really only giving 9kWh (or needs 11kWh to charge 100%). Yearly savings are now only $450 a year.
Batteries also degrade. A Lithium battery with a 10 year warranty, might only be producing 60% – 80% of it’s rated capacity by that time. We’ll be generous and assume nearly 90% of total energy throughput of the 10kWh/day advertised. Yearly savings are now only averaging maybe $400 a year.
A good quality 10kWh battery can cost more than $10,000 when fully installed with the required electronics. Over it’s 10 year warranted life, it will save you perhaps $4,000. Probably doesn’t sound that attractive does it?
You could shop around for a cheap battery but if you’re not careful, you might get lower capacity, lower charging rates, lower quality (degrades faster or fails) or lesser warranty. They’ll see you coming and sell you on the good feelings you’ll have when you join the battery owners club.
In conclusion? It’s expensive, but you can add a battery to your existing solar system. There are plenty of other reasons to get a battery, just don’t expect it to make economic sense until battery prices drop significantly.