Hello everyone!

[bram]

Hi everyone,

Just found this forum while doing some searches for DIY home batteries and realised I had to join!
Me and my gf bought our first home a few months ago. Since it is built in 1939 it is quite old and terribly insulated. We are doing a whole lot of renovation etc. We are gonna get 16 solar panels and I was thinking about getting or building a home battery for storage. I also drive a Tesla Model 3 with 75kwh, but I do not have a charger at home yet.

Love to learn more about batteries and the whole home power storage practices!

 

[DG98]

Welcome to the fun. It sounds like you are on the right track with renovating your home. When I purchased a house built in the early 1960s, the first order of business was major re-insulating. That made a bigger impact on my energy usage than anything else we have done. (And it's dramatically cheaper to deploy than most other options, too.)

There are some great FAQs and sticky posts here you'll want to read. You've got some high-level decisions to ponder, such as whether you want to grid-tie your panels or keep them isolated / off-grid for self-consumption only. That analysis will inform what kind of inverter you need -- tied, off-grid, or hybrid. Also think about your goals for energy storage. Do you want to be energy independent, able to go fully off-grid? (Here's a quick tip -- with an older home plus an electric car which you presumably would like to be able to charge at home, being grid-independent is a much larger challenge for you than for some.) If your goal is "energy backup" for a grid outage, that's likely much more attainable -- and you can do some "energy offset" when your battery bank is full and the sun is out.

Are you interested in building a DIY / homemade battery pack, or do you think you'll stay Tesla-loyal and just buy one of their pre-fab Powerwall devices? (A number of other manufacturers also offer varying degrees of plug-and-play battery banks, but the Tesla Powerwall is probably best known through marketing. Around here you will find that the term "powerwall" is used pretty generically for any stationary home energy storage solution, including a lot of our homemade solutions.) Either approach is viable -- it just comes down to personal preferences, budgets, free time, etc., etc. But again, that decision may cascade to impact some of your other choices, like which inverter is the best match for your intended system. If you choose to assemble your own battery bank, then you get to tackle which battery management system (BMS) to use, how / whether the BMS will interact with your inverter, and more -- that conversation alone is the subject of many pages of posts here.

Go forth and read, and then ask questions. There's a great group of people here, and many of them are very happy to share their knowledge and experiences with others. When you've had time to get a little more focused about your intended approach, start asking questions and I bet you get some solid responses.

Another quick tip -- you might want to update your profile to indicate your general location. That's often relevant for things like how much sun you are likely to get on your panels, shipping distances from various vendors, and so forth.

Cheers, John

 

[bbbbrass]

Welcome! Where are you located? It's super addictive to scrounge, salvage, scrap, and make an 18650 pack, but for home storage it will be far quicker and easier to make a prismatic LiFePO4 pack if you go DIY. I would advise looking at the projects in chunks, and not get overwhelmed or start buying things too quickly!

 

[RetiredAutoTech]

Glad to see you in here. I'm also new around here and have learned alot by just reading as much as I can. At first I was jumping head first into all of this but have decided to focus on analyzing my usage before building anything. Trying to figure out steps and cost of each step before doing or making a mistake.

 

[bram]

Welcome to the fun. It sounds like you are on the right track with renovating your home. When I purchased a house built in the early 1960s, the first order of business was major re-insulating. That made a bigger impact on my energy usage than anything else we have done. (And it's dramatically cheaper to deploy than most other options, too.)

There are some great FAQs and sticky posts here you'll want to read. You've got some high-level decisions to ponder, such as whether you want to grid-tie your panels or keep them isolated / off-grid for self-consumption only. That analysis will inform what kind of inverter you need -- tied, off-grid, or hybrid. Also think about your goals for energy storage. Do you want to be energy independent, able to go fully off-grid? (Here's a quick tip -- with an older home plus an electric car which you presumably would like to be able to charge at home, being grid-independent is a much larger challenge for you than for some.) If your goal is "energy backup" for a grid outage, that's likely much more attainable -- and you can do some "energy offset" when your battery bank is full and the sun is out.

Are you interested in building a DIY / homemade battery pack, or do you think you'll stay Tesla-loyal and just buy one of their pre-fab Powerwall devices? (A number of other manufacturers also offer varying degrees of plug-and-play battery banks, but the Tesla Powerwall is probably best known through marketing. Around here you will find that the term "powerwall" is used pretty generically for any stationary home energy storage solution, including a lot of our homemade solutions.) Either approach is viable -- it just comes down to personal preferences, budgets, free time, etc., etc. But again, that decision may cascade to impact some of your other choices, like which inverter is the best match for your intended system. If you choose to assemble your own battery bank, then you get to tackle which battery management system (BMS) to use, how / whether the BMS will interact with your inverter, and more -- that conversation alone is the subject of many pages of posts here.

Go forth and read, and then ask questions. There's a great group of people here, and many of them are very happy to share their knowledge and experiences with others. When you've had time to get a little more focused about your intended approach, start asking questions and I bet you get some solid responses.

Another quick tip -- you might want to update your profile to indicate your general location. That's often relevant for things like how much sun you are likely to get on your panels, shipping distances from various vendors, and so forth.

Cheers, John

Welcome! Where are you located? It's super addictive to scrounge, salvage, scrap, and make an 18650 pack, but for home storage it will be far quicker and easier to make a prismatic LiFePO4 pack if you go DIY. I would advise looking at the projects in chunks, and not get overwhelmed or start buying things too quickly!

Glad to see you in here. I'm also new around here and have learned alot by just reading as much as I can. At first I was jumping head first into all of this but have decided to focus on analyzing my usage before building anything. Trying to figure out steps and cost of each step before doing or making a mistake.

Thanks for the warm welcome guys!

We are planning on insulating the space between our walls this year and getting proper windows installed, so that will safe a lot of money probably. My ultimate goal would be to charge the battery during the day or when the energy prices are low (we have an energy contract were prices vary by the hour). Maybe even return power to the grid when prices are high. I heard this would also be possible with certain electric cars and some home charges, but that would be extra.

Good idea to build it in chunks! That would be my preferred way of doing it. If it the battery can be build as modules and added to increase capacity that would be ideal!

Thanks for the tip @RetiredAutoTech! Budget is currently quite low due to all the other renovation so planning will be very important

I live in the Netherlands btw

 

[DG98]

We are planning on insulating the space between our walls this year and getting proper windows installed, so that will safe a lot of money probably. My ultimate goal would be to charge the battery during the day or when the energy prices are low (we have an energy contract were prices vary by the hour). Maybe even return power to the grid when prices are high. I heard this would also be possible with certain electric cars and some home charges, but that would be extra.

I'm not an engineer, but one of my close friends is an architect who works with an engineering company, who has been helping me design a new home. He is forever lecturing me that the vast majority of heat escape is through the roof of the structure, and that insulating your roof / ceiling / attic area is far more important than worrying about your vertical walls. After that, he stresses sealing air leaks and gaps. Finally he gets down to walls, windows, and doors. Just info that has been preached into me and might be useful in your project. Plus, those roof/attic areas tend to be much easier to improve compared with getting into existing walls, though you might have an opportunity to do both during renovations.

You raise some interesting twists here, too -- such as charging your battery bank during low-cost periods. That's likely going to require an AC charger that pulls from the grid to charge the bank when the sun isn't shining, or else a hybrid inverter that contains the same functionality and parameters to control charging times from a grid input. I don't think a whole lot of people here are doing that, focusing instead on charging from solar panels during the day. (Many of us have a surplus of panels, allowing simultaneous powering of loads AND charging the battery bank during those peak sun hours. Others who are grid-tied don't care, since they basically treat the grid as a battery -- feed in all you can during the day, draw some back at night.) Shifting is more common, to offset those peak-cost periods with solar and/or battery power, but if your intent is to charge your battery bank in the dead of night you're going to need equipment that I suspect not many of us are using.

Also, I don't know anything about feed-in tariffs and net-metering type regulations in the Netherlands. Most power companies in the U.S. are not so generous about compensating local generation (individual household feed-in) according to the same schedules for high rates, etc. -- many only offset your hours used, or buy excess generation only at wholesale rates (rather than the much higher retail rates). You'll have to do some research on how it's handled where you live, because that might greatly impact whether some of your plans are practical.

Thanks for the details -- I look forward to hearing more about your plans and projects as they evolve and come together.

Cheers, John

 

[italianuser]

Welcome to you, nice to hear about your plans!

I'm a low-budget/recycling DIYer, for e.g. I'm saving on the structures to hold the PV panels (mounted on a balcony, not on a roof) so the expense is quite big to buy those metal structures. I bought myself a welding machine (around 220€ with mask, gloves and the electrodes) and the metal (440€ for 66 meters of 30x8mm2 bars) and I'll take my time this year to make this metal skeleton. So I'm spending a lot less (1550€ VS 660€) but I have a lot to learn!

 

[cak]

making a mistake

There are no mistakes just experiential learnings

He is forever lecturing me that the vast majority of heat escape is through the roof of the structure, and that insulating your roof / ceiling / attic area is far more important than worrying about your vertical walls. After that, he stresses sealing air leaks and gaps. Finally he gets down to walls, windows, and doors.

The research I have from the Building Science Institute disagrees with the whole roof looses most heat folklore. The main reason folks use for that argument is that since heat rises more goes out the top but in reasonably airtight spaces buildings there shouldn't be much stratification of heat form the lower level to the ceiling. That being said there are practical and cost reasons why having extra insulation in the ceiling can make lots of sense because if you have an attic it is relatively cheap and easy to ass LOTs of insulation there relative to what it takes to insulate walls and such. Interestingly most building codes I have seen here in the USA still have not caught up to the science and have higher ceiling insulation requirements. The research I have read has said that air sealing is the absolute most important factor in heat loss. Unfortunately air sealing also increases the risks of poor quality work or construction materials because it keeps any moisture in and so the home doesn't "breath"(read leak) like old houses do. Here is a place to start learning the advanced building science https://buildingscience.com/documents/digests/bsd-011-thermal-control-in-buildings

I would also recommend looking into the Living Building Challenge which takes green/sustainable building to the extreme, https://living-future.org/lbc/. I am also partial to the epic way they build in Germany and Switzerland with all wood based vapor open high performance building.

I live in the Netherlands btw

I highly recommend learning about local rules and regulations from all levels of government AND your utilities as there can often be hidden pitfalls that limit DIY options so best to be informed early so you don't waste time/money heading in a route that won't work. https://www.youtube.com/@TheKilowattChallenge could provide some inspiration and an example of the challenges that can cause redirections of your dream.

 

[bram]

I'm not an engineer, but one of my close friends is an architect who works with an engineering company, who has been helping me design a new home. He is forever lecturing me that the vast majority of heat escape is through the roof of the structure, and that insulating your roof / ceiling / attic area is far more important than worrying about your vertical walls. After that, he stresses sealing air leaks and gaps. Finally he gets down to walls, windows, and doors. Just info that has been preached into me and might be useful in your project. Plus, those roof/attic areas tend to be much easier to improve compared with getting into existing walls, though you might have an opportunity to do both during renovations.

You raise some interesting twists here, too -- such as charging your battery bank during low-cost periods. That's likely going to require an AC charger that pulls from the grid to charge the bank when the sun isn't shining, or else a hybrid inverter that contains the same functionality and parameters to control charging times from a grid input. I don't think a whole lot of people here are doing that, focusing instead on charging from solar panels during the day. (Many of us have a surplus of panels, allowing simultaneous powering of loads AND charging the battery bank during those peak sun hours. Others who are grid-tied don't care, since they basically treat the grid as a battery -- feed in all you can during the day, draw some back at night.) Shifting is more common, to offset those peak-cost periods with solar and/or battery power, but if your intent is to charge your battery bank in the dead of night you're going to need equipment that I suspect not many of us are using.

Also, I don't know anything about feed-in tariffs and net-metering type regulations in the Netherlands. Most power companies in the U.S. are not so generous about compensating local generation (individual household feed-in) according to the same schedules for high rates, etc. -- many only offset your hours used, or buy excess generation only at wholesale rates (rather than the much higher retail rates). You'll have to do some research on how it's handled where you live, because that might greatly impact whether some of your plans are practical.

Thanks for the details -- I look forward to hearing more about your plans and projects as they evolve and come together.

Cheers, John

That is indeed something I need to do some research on! The feed-in compensations are going to be cut off in the next few years anyway so it won't be a long term solution.

 

[bram]

Welcome to you, nice to hear about your plans!

I'm a low-budget/recycling DIYer, for e.g. I'm saving on the structures to hold the PV panels (mounted on a balcony, not on a roof) so the expense is quite big to buy those metal structures. I bought myself a welding machine (around 220€ with mask, gloves and the electrodes) and the metal (440€ for 66 meters of 30x8mm2 bars) and I'll take my time this year to make this metal skeleton. So I'm spending a lot less (1550€ VS 660€) but I have a lot to learn!

Oh that is awesome! I have never thought about that!
We have something in our mortgage (no clue what it is called in English) that is loan for making your house more sustainable and energy efficient (like insulation and solar panels) so we will use that for the solar panels.

Sounds like you have a lot of fun work ahead of you! Would love to see your progress

 

[bram]

There are no mistakes just experiential learnings

The research I have from the Building Science Institute disagrees with the whole roof looses most heat folklore. The main reason folks use for that argument is that since heat rises more goes out the top but in reasonably airtight spaces buildings there shouldn't be much stratification of heat form the lower level to the ceiling. That being said there are practical and cost reasons why having extra insulation in the ceiling can make lots of sense because if you have an attic it is relatively cheap and easy to ass LOTs of insulation there relative to what it takes to insulate walls and such. Interestingly most building codes I have seen here in the USA still have not caught up to the science and have higher ceiling insulation requirements. The research I have read has said that air sealing is the absolute most important factor in heat loss. Unfortunately air sealing also increases the risks of poor quality work or construction materials because it keeps any moisture in and so the home doesn't "breath"(read leak) like old houses do. Here is a place to start learning the advanced building science https://buildingscience.com/documents/digests/bsd-011-thermal-control-in-buildings

I would also recommend looking into the Living Building Challenge which takes green/sustainable building to the extreme, https://living-future.org/lbc/. I am also partial to the epic way they build in Germany and Switzerland with all wood based vapor open high performance building.

I highly recommend learning about local rules and regulations from all levels of government AND your utilities as there can often be hidden pitfalls that limit DIY options so best to be informed early so you don't waste time/money heading in a route that won't work. https://www.youtube.com/@TheKilowattChallenge could provide some inspiration and an example of the challenges that can cause redirections of your dream.

Good point about the air leaks! I might do some more research on that topic