frank li wrote:
There was a drill motor with a pv module attached to it in your house build video. I am all over it.
frank li wrote:The figure you gave is instantaneous power (2.88kw) a solar day has hours. 28,000 btu/hr is accumulated over the solar day. Solar thermal systems often have 50% and higher total system efficiency on the thermal side. Please dont think i do not see your point.
Again you have a path based on your environment, resources and capability and your tech is good. My comment is for others.
I have given problems to solve to whole classes of industrial engineer grad students and watched them miss by a long shot for the lack of listening.
frank li wrote:
What is the duration of extreme delta-t at your location? The reason i ask is not to convince you of the merits of solar thermal, rather to clear the pad for others adopting RE to know that extreme cold temps are generally not the major portion of heating degree-days. There is much benifit to collecting heat in the fall, much of the winter and in the spring, temp and solar availability-wise in my area of operations (northern michigan).
Also, i have made a living designing and installing these systems, part of that work was bringing orphan systems back online. Most of the ones that stopped operating needed a sensor or controller. Pumps rarely were the cause and air blower-motors, occasionally, a rotten copper waterway...once, heat transfer fluid turned to goo or acidic from stagnating 5 years...yup.
Funny thing, the thing that brought most systems down is new roofing and no service proffesional or handy person. They would re-mount and never charge with fluid.
most of these systems were 30 plus years old when i serviced them starting 12 years ago, they are ready for another 30-60 years of service or as long as the polyiso insulation survives... then 1.5 sheets of iso and a screwdriver to get another 60 years.
If distilled water is used in a drainback system that is pv direct circulated, an evacuated tube system could easily be a 100 year machine that requires a rare frequency of parts replacement. I excluded thermosiphon with antifreze and heat exchange and plain thermosiphon systems because of our extreme climates and the need for expensive chemical antifreeze, because distilled water is so easy and impervious.
Solar air heaters may leak 'fluid/air' but it is not as problematic if it were to occur. They require no freze protection and sometimes no blower or automated damping for regulation. They produce 28,000-32,000 btu/hr per day per 4'x8' collector at my lattitude and weather conditions. Thats like many peoples furnace at full blast for an hour per day per collector or 9kwh per!
Saskatchewan is tough territory. I am checking climate data now, for my own curiosity.
I am keenly awaiting data-logging details of your heater. Because we get smarter every day!
frank li wrote:Our consumption here is 450-650whr/day avg. or 15-20 kwh/month. The boiler system has its own 223w module and 85ah gel cell, so the main pv system only powers lights, communications and well pumping. We garden and pump alot of water in the summer. I have been installing solar thermal and pv since 2004 and i would like to talk with you about your drill motor. I use a morningstar sysem (cc and inverter) in a dewalt drill case for charging an sla with a 10w module...but i live in an off the shelf world of lead acid!!!
Pv direct charging i love it.
Next thing here is to supply power over ethernet from a dc to dc sps(s) to every powered load i can, the coffe table, light fixtures, display screens, computers, routers and other comms, control for boiler and solar hydronics, and monitoring. I install sps devices to dc systems in cabins with existing dc power for lights and well pumps already for conditioning and low voltage protection and p.o.e systems are interesting. Thanks for the chat Dacian, and i hope to hear about your drill!
frank li wrote:
I love your home and i could picture a few thermosiphon driven air heaters or hydronic solar collectors on there for reducing the array size. However...copper cables do not leak water or air! I noticed that you do not live in woodland. We rely on a woodfired boiler system attached to our stove inside for dhw and space heat distribution. It dries clothes, heats the house and water and cooks our food all at the same time. I use pv direct-drive pumps and pv direct delta-t controllers for solar thermal and battery powered control and pump of the same type for the boiler side. I am shifting toward a destruction free source and so i applaud your clean style. We did find research that showed that wood heat, even at low efficiency can be much more efficient than industrial fuels. We harvest only dead wood and use mainly manual labor to harvest and haul (used to use a bow saw) and use an electric chainsaw with organic soybean oil as bar and chain lube. An outdoor combustion air inlet to the stove completes the picture. Sorry about the book but your house build and location got me all excited. Like yourself, we do it on 740wp of pv. These systems are micro to my clients but i live this way with great effect.
frank li wrote:Im a pv system designer and also live off grid. We are always looking for equipment that solves problems and shaving off equipment and problems when possible. Your solar electric system outline makes me think that you like to shave! I do not run lithium, but am adjusting to the tecnological landscape.
These chats help evolve the techniques that are our toolbox and capability. I will take a look at your devices.
Vehicle propulsion is one of the most extreme purposes an electric battery can be put to use for. The guys at evtv show that they bottom balance a battery of cells and use 80% of its rated capacity, for years of commuter use without getting any significant unbalance. They do monitor cells and use auto contactors to avoid low voltage induced failure. The battery has enough ampacity to soak up the difference between cells as long as the application does not require every nameplate amp-hour to be used. Sometimes this is referred to as not getting your best dollars per amp hour capacity, and sometimes doing so solves problems and shaves equipment.
frank li wrote:These are great sources of off the shelf solutions to the lithium issue.
The problem with the bulk of lifepo4 batteries designed for sla replacement is, that they are made of multitudes of paralelled cells of tiny capacity and too many connections inside...plus bms circuitry. Stay away from this or...fire and economic failure and or overall disappointment in/of an otherwise well designed system may occur.
Pv system design just broke the 4s20p battery habit and ev hobbyists are doing it right without bms and doing it in single series strings with big cells (100ah-500ah not a quadruple gross of 5000mah cells), big cables and great results.
frank li wrote:
One limitation of lifepo4 is that they generally are not able to be charged at low temps (0 deg f) and need an automated climate control system (insulation, heat source, controller etc.) in order to operate reliably unattended, and need a heated location either way for 4 season use in areas with cold winters.
Terry Ruth wrote:
Here is a thread and post from an installer that discuss micrometers vs DC optimizer. Is this accurate? What is your take on them are they worth the COP and how they differ from the efficiency of your efforts? I've read the studies out of CA showing higher efficiency from west-south facing hybrids....are you facing any west? https://permies.com/t/45940/solar/micro-central-inverter