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How to add Batteries to a roof solar system?

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  • #16
    Originally posted by PNPmacnab View Post
    The solar world has been stuck on batteries for a long time. If the world ends as we know it, you need to learn how to live differently. You have a lot of power from those panels and you can just use it when it is there. Technically, you don't need batteries. I have refrigeration, hot water, dishwasher with heated dry, all the usual stuff and when I get around to it a clothes washer. And I've had no need for anything beyond my car battery. I do things when the sun shines. That is not where the market is and you can't get the equipment to do it. What are you going to do when you can't go down to Walmart and get another battery. I've watched a few prepper videos and the first thing that comes to mind is these people are all going to die in a real crisis.
    More bad advice to morons.
    MSEE, PE

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    • #17
      "That is not where the market is. . ."
      I think you mean that the market would rather I spend $ on batteries,

      No, big and dumb solar systems will always work. If it were easy, everyone would be doing it. You are seeing pumps that run directly on solar. Doing that with multiple devices is a big challenge. It takes complex energy management to use solar energy without a large battery. Even some simple scheduling can greatly reduce battery requirements. As mentioned in another thread, energy management for a simple air conditioner doesn't come cheap. And people don't understand scheduling. It will have to have some fuzzy logic system up in the cloud that learns your habits. Still think it is important to know it can be done and set a higher goal for systems out there. If you understand the technology, it can all be done now. I've implemented some parts of it. It just can't be copied because every system is different.

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      • #18
        Sunking, perhaps you'd care to ADD something to the conversation, instead of just criticising?

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        • #19
          Originally posted by PNPmacnab View Post
          "That is not where the market is. . ."
          I think you mean that the market would rather I spend $ on batteries,

          No, big and dumb solar systems will always work. If it were easy, everyone would be doing it. You are seeing pumps that run directly on solar. Doing that with multiple devices is a big challenge. It takes complex energy management to use solar energy without a large battery. Even some simple scheduling can greatly reduce battery requirements. ..........
          Some of those are probably more relevant points for the Off Grid section of this forum.

          For grid tie systems the market seems to be going toward batteries. At least from my perspective in California where the build out of solar has created a market for storage. The duck curve is becoming such an issue that curtailments of commercial solar have more than doubled since 2018. That threatens to wreak havoc with ROI of commercial wind and solar. Energy storage is the solution to that dilemna.

          As far as the topic of this thread is concerned, if the national trend toward more solar generation continues we may see a continued shift in the time periods of TOU rates or toward more TOU rates where none exist now. That may reduce the ROI of rooftop solar. Jack Rickard of EVTV fame actually thinks there is a conspiracy among power producers to use frequency shift to knock rooftop solar off line. I don"t buy his conspiracy theory but I have invested in a hybrid inverter to give me a hedge and provide some resiliency. At this point it is just a hobby..
          Last edited by Ampster; 07-07-2019, 08:25 PM.
          9 kW solar, 42kWh LFP storage. EV owner since 2012

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          • #20
            If I remember right, the OP took us down this prepper route. The utilities tried to satisfy the green movement with all these concessions when they thought solar wouldn't amount to much. Now their way out is time of use. Big batteries are great for those who want it and want it now mentality towards energy, unfortunately that is what most want. It is also practical for the vast amounts of older devices in their homes. GE had their Geospring water heater with a communications port. Even the most talented could barely make that do anything. Now there are even wifi connected crock pots. The general public is ill equipped to do anything technical. The only reason the VCR stopped flashing 12:00 is they became obsolete. At some point someone will offer online services to manage all these devices to save energy. I'd rather store cold and heat instead of a battery.

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            • #21
              Originally posted by PNPmacnab View Post
              ....... The only reason the VCR stopped flashing 12:00 is they became obsolete. At some point someone will offer online services to manage all these devices to save energy. I'd rather store cold and heat instead of a battery.
              I used to have a voice activated VCR. Then she went off to college and the lights started flashing again. LOL.

              My Geospring is still working and I use IFTTT to raise the temp when my solar output hits a certain kW output in the morning. I also use IFTTT to set back in the evening. (It is still warm enough from the day before for a quick shower early in the morning. My Nest thermostat can also be triggered to cool the house in the day.

              I do think the Power Companies are missing the boat not offering online services. As more and more load departs from the grid, they are going to be left with a declining revenue stream. I get paid $5 per month to let an independent company turn off my car charger when the grid is stressed. The irony is that I rarely charge my car during those times. I look forward to the day that they pay me to charge my car instead of curtailing commercial solar. Tesla Powerwalls can be aggregated and I think some states are actually paying for that aggregate load when needed. I am surprised it has not happened in California.
              9 kW solar, 42kWh LFP storage. EV owner since 2012

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              • #22
                Originally posted by Mark2407 View Post
                Sunking, perhaps you'd care to ADD something to the conversation, instead of just criticising?
                Mark you are being told what you want to hear and the advice is very dangerous. Use to be a time when dangerous advice was not allowed on this forum.

                MSEE, PE

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                • #23
                  Originally posted by Sunking View Post
                  Mark you are being told what you want to hear and the advice is very dangerous. Use to be a time when dangerous advice was not allowed on this forum.
                  In that case, Sunking, could you please add some advice that is not dangerous, but, instead, Helpful?

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                  • #24
                    All I want to say is I do this stuff and don't understand why more don't. If you are really interested in a topic you should want to learn something new, like a little electronics. Solar forums are totally boring, what wire do I use. Forums are supposed to be a place where people interested in a subject discuss new ideas. I'm doing things that are totally pedestrian, embarrassing low technology and people can't comprehend them. Solar is the only thing I know where everyone is so happy if it even works at all. Running without batteries is hardly earth shattering.

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                    • #25
                      Originally posted by PNPmacnab View Post
                      ...If you are really interested in a topic you should want to learn something new, like a little electronics. Solar forums are totally boring, what wire do I use. Forums are supposed to be a place where people interested in a subject discuss new ideas...
                      Along those lines...I'm going to take a chance and try to hijack this thread (sort of) to discuss something similar. Something definitely more "out of the box"...

                      What about a "modular" or maybe a better word is "distributed" hybrid system? I would like to dabble in solar power...add a bit here and a bit there over time. I understand that wouldn't be the most cost-effective route. But, hear me out.

                      I live in the country. Not way out in the boonies, but out a bit. On 6 acres of mostly woods. I am by no means a prepper - but I do like to do things that make me more self-sufficient. We have chickens, bees, a garden. Yes, I completely understand that I spend more money feeding my chickens than if I bought eggs at Walmart, but it's FUN and the eggs are way better! Along those lines, having power during grid outages to power certain things would be nice. No, no, I'm not talking zombie apocolypse.

                      So, I thought I might start with my well pump. I built a data logger from an Arduino, a shield with RTC and SD card, and a clamp-on current sensor - found that it draws 12.5A running (220V), surges at 31ish on startup, and uses a measley 0.2 KWh on an average day. I'd use an inverter with built-in transfer switch, MPPT charge controller, and maybe a grid charger. LiFePO4 battery plant and set charge parameters to take it easy on the batteries so they last a long time. Priority would be to the solar/battery so it would basically use all of that available and switch to grid when not. Some savings on utility bill, but not much - I pay about $0.12/KWh total. No changing of rates at different times, etc. Pretty cheap here...

                      Depending on how that worked, maybe next add a circuit for freezer, fridge, and sump pump. And so on.

                      I know that opens a huge can of worms, much of which I am already thinking about, so I'm not going to try to address it all up-front. Rather, I'm hoping for a fun, civilized, discussion. Maybe I'm dreaming. Some of the pros and cons are obvious:

                      con: likely more costly in long run
                      pro: failure of one subsystem wouldn't effect others (i.e. 1 inverter failure doesn't knock out whole house)
                      con: difficult to make supportable by anyone else (but, we intend to live here until the end)
                      pro: it would be fun!

                      OK, let's see where this goes - if anywhere.

                      Thanks,
                      Wally
                      Last edited by wallyblackburn; 08-01-2019, 04:02 PM. Reason: Typo

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                      • #26
                        Renewable energy tends to dribble in over long periods of time. Your well pump is the exact opposite,
                        very big surge but very low average. It is the last thing I would try to run from a battery plant, esp if
                        the grid was available. Money wise you will lose money on batteries and create a new maintenance
                        hobby. My choice would be something that could run from the solar, with line backup. Net metering
                        is the best payback (no batteries), but of course does not help you be independent. Bruce Roe

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                        • #27
                          I completely understand that net metering is the best way to recover cost and save $$$. At the prices we pay around here, I think it would be hard to justify solar at all if that were the primary driver.

                          As far as maintenance, I was thinking LiFePO4. With a gentle charge profile, I think maintenance would be near-zero. But you are 100% right that the system would get very little real use. Maybe a larger setup with split-phase output that also ran a few other circuits. But then I need to think about a subpanel and it turns in to a bigger deal. I have thought about starting with a critical circuits subpanel for all circuits I might want to add eventually. That could also be used for generator feed.

                          This is the problem - I start thinking about it and end up overwhelmed with 43 different possibilities/decisions!

                          Wally

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                          • #28
                            Originally posted by wallyblackburn View Post
                            I completely understand that net metering is the best way to recover cost and save $$$. At the prices we pay around here, I think it would be hard to justify solar at all if that were the primary driver.

                            As far as maintenance, I was thinking LiFePO4. With a gentle charge profile, I think maintenance would be near-zero. But you are 100% right that the system would get very little real use. Maybe a larger setup with split-phase output that also ran a few other circuits. But then I need to think about a subpanel and it turns in to a bigger deal. I have thought about starting with a critical circuits subpanel for all circuits I might want to add eventually. That could also be used for generator feed.

                            This is the problem - I start thinking about it and end up overwhelmed with 43 different possibilities/decisions!

                            Wally
                            I found that more self education helped organize my thinking.

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                            • #29
                              Originally posted by Sunking View Post

                              More bad advice to morons.
                              Hey, they watched Walking Dead and know the future. :P

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                              • #30
                                As for adding batteries, it's doable depending on how much money you want to spend. Whenever I get bored, have money to burn, or my electric company stops net metering I'll do a sort of hybrid system. Leave my current grid tied system in place, split out my load panel into a critical loads panel, then create a smaller off grid system which will run probably most of the house not including the big power suckers. If I run out of power just flip the switch back and run from the grid again. This would be similar to how backup generators work.

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