About Romain
Romain is living off-grid with his family in one of the most beautiful tropical islands, Palawan, in the Philippines.
Romain is a Chemical Engineer with a Ph.D. in Chemistry from Ecole Polytechnique, France. He is a surface science specialist and an electrochemist.
He dedicated his studies and early career to scientific research in renewable energy. His first research project goes back to 2006 when he contributed to developing hydrogen storage material for Philips in the Netherlands. In 2010, he completed his Ph.D. thesis: “Toward hydrogen photoproduction by immobilized bio-inspired catalysts.” The thesis was supported by a co-authored article published in Science.
In 2011, he joined the French National Research Agency to support ambitious research projects in the field of Energy. For 7 years, he supervised hundreds of fundamental and applied research projects covering a broad spectrum, including the Energy economy, solar energy, battery storage, smart grids, hydrogen technology, and thermoelectricity.
Currently, he is developing an eco-resort in the Ulugan Bay, near one of the natural wonders of our world, The Sabang Underground River, Palawan, Philippines. Ocean Green is a project focused on sustainability and self-sufficiency. It’s a lodge and an experimental field for sustainable resort development.
Romain led the project in developing an 11 – 30kW off-grid solar system, rainwater collectors, and geo-filters alongside an organic garden for their farm-to-table restaurant and to supply the local market.
Romain also loves sharing his knowledge and practical applications. That’s why he was one of the first to join the team at Climatebiz in 2020.
You will find most of his articles on the topics related to solar energy and battery storage.
Romain Metaye can also be found on, Research Gate, Google Scholar & LinkedIn
Education
User Posts: Romain Metaye
It's vital that you select the correct size solar generator to run a refrigerator during a power outage or camping trip. Today, refrigerators are our most ...
Romain Metaye
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hi! thank you for your comment, and interesting question.
1. One of the main difference between lead-acid and lithium batteries is the built-in BMS (battery management system) in lithum batt. A protection board that limits overcharging, overheating, overdischarging… If the battery is fully charge the BMS will shut down the battery cells and protect your battery pack from being overcharged.
Therefore you shouldn’t worry about overcharging your battery.
As stated in the article we do recommend to use a DC-DC charger between the alternator and the starter lithium battery. This will ensure a proper charging profile and extend your battery life.
2. Your second lithium battery is connected to the starter battery. having a DC-DC charger in between the two batteries is wise, specially if they have different voltage. Having a second battery with a different voltage from the first one is not a problem. Again, the BMS makes your battery “smart” so they won’t be damaged.
For example if battery 1 can only provide a max of 50A at 12V (600W) then it will only delivers this power to the second battery. The DC-DC converter will rise the voltage to 24V (or 36V) and reduce the current to match the 600W output of your first battery.
In summary, lithium battery are much “smarter” than lead-acid. They are also much more robust to rapid current fluctuation and they accept fast charging/discharging. They keep their charging state for months.
Simply use DC-DC chargers for a proper charging profile.
Hope this helps!
Hope this helps
Hello Jason, thank you for your message and appreciation. Inverters are designed to work continuously, as long as you don’t overload them. For example, I have been living on two inverters (6.5kW and 3.5kW) for more than a year now. They’ve been running 24/7 with only minors shutdowns (few seconds). Pretty amazing.
Then the duration you can run them also depends on the size of your battery. Have a look at this great article: https://climatebiz.com/battery-size-chart/
You’ll find charts with running times of different appliances in function of the battery size.
Hope this helps!
Hello Bob,
Thank you for your comment.
You’re totally right, the Powerwall+ came out last year and has a 7.6kW PV inverter, and a combined capacity of 135kWh.
It is not directly integrated to the Powerwall battery unit though.
You’ll have this 7.6kW inverter in a separate wall-mounted box.
Hi Martin, thanks for your comment. I can definitely help you. Could you kindly let me know the power of your solar panels, your approximate location and the appliances you are powering with your system.
Thanks for your appreciation. With new technologies, anything can happen. Even significant price drops. Look back at solar panel price .In the early ’00s, it was 2000% (20x) more expensive!
Hello Neil, thanks a lot for your comment. You are correct, you only need a DC to DC charger connected to your alternator.
The alternator will deliver a steady 14V DC and the DC converter will modify it to the right charging profile for your batteries. If you’re looking at some quality DC converters, Victron’s products are a good pick.
Hello Terrence, thanks for your comment. Indeed, charging a lithium battery is not a 100% efficient process. You’ll loose between 1 and 5% of energy. For a 1kWh battery that’s between 50Wh and 10Wh. Then discharging is 99% efficient so you’ll lose 10Wh for a 1kWh battery.
The cost of the electricity for charging is not included in our lithium battery price because it is a variable information. One could use Solar energy at $0.05/kWh or an other charge it with utility electricity in Hawaii at $0.5/kWh. In addition the price of grid electricity fluctuates over the years.
You’re welcome! You should wire your DC charger directly to the battery.
Hello Red, thank you for your comment. Yes you can charge and power loads at the same time. For example, if your load is 500W and your charging power is 1000W, then only 500W will go into the battery.
Thank you for your comment Dirk !
All the ESS featured in the article offer time-of-use (TOU) management. As you mention it, without solar panels, the ESS charges when the electricity price is low and power your house when electricity prices are high.
Now, let’s do the math.
I’ll take for example, the TOU in California. They have a rate plan named TOU-D PRIME.
During weekdays, electricity costs $0.21/kWh between 9pm and 4pm and $0.54/kWh during peak hours between 4pm-9pm.
That’s $0.33/kWh difference!
If one gets the PowerPod 2 featured in this article, it has a Levelized Cost of Storage (LCOS) of $0.18/kWh. This figure is based on the total number of cycles for this ESS (6000 cycles) divided by its price, inc. installation.
It means that every kWh that you will charge and discharge from the ESS will cost you $0.18.
The battery will charge during low hours at $0.21/kWh, add $0.18 and you’ll get a real cost of $0.39/kWh.
During peak hours, you will be saving: $0.15/kWh with your ESS.
In the end, you can save money even without solar panels, it all depends on the rate of your local TOU and the LCOS of your Energy Storage Solution.
To save even more, add solar panels, self-consume your electricity as a priority, then sell the surplus to the utility company.