Using excess solar to heat house

[Daddy Tanuki]

I know it's off topic, but as an enthusiast what's your opinion on the Einhell Power X-Change 10 inch 18V Cordless Chainsaw model GE-LC 18/25 Li With 3.0 Ah Battery (it's the one I have)

I bought it as I have a number of Ozito and Einhell tools and the batteries are interchangeable. Been using it to take down a few trees and think it's a great electric chainsaw

I will say (without having ever used one) that I am not keen on the twist and lock style bar clamping systems. (From my research) I think I would prefer two lock down nuts as the bar never slips. how well does the Einhell work? Stihl and Husky tried the quick lock system but stopped using them after one model or so as they did not clamp well enough to keep the pro users happy. That's what i base my evaluations off of. electric battery saws are starting to gain acceptance among the pro community, so they are definitely coming up.

 

[Daddy Tanuki]

Might look into stored hot water. Cheaper than batteries at least in the states. 1 50gal water heater is about $600 new or less if scratch and dent. Maybe $700 for hybrid with rebates or $1300 full price...scratch and dent can be half the price. 50 gal stored water is about 8 kwhr.
I like the idea for domestic hot water but also for supplemental heating. The hybrid hot water heater systems are so cheap relatively speaking it can be a poor man's equivalent to geothermal if you have a large basement. The cold air output sinks quickly and hits the concrete floor at 60deg F which warms it to 60F almost immediately as it covers the large surface area. A smaller basement may not be as good in that respect and could steal some of the house heat. I've been using one and this is the effect I've seen but I have a large basement about 2100ft2.

funny check some of my other threads... I have been looking at a 12kl stainless tank for the same reasons. I keep getting people saying it will not work but I think it will.

 

[Daddy Tanuki]

My 3 year old used 250w panels , were $58 each.
I've bought 6kw so far, and will probably triple my array for that low price.

thats a sweet price compared to Japan. shit at that price i would have 25 kw or more!

 

[timselectric]

Planning for at least 24kw.
I have the available roof space.
Would rather have too much, than not enough.
Especially at these prices.
Maybe I can make electricity from moonlight. lol

 

[Daddy Tanuki]

Planning for at least 24kw.
I have the available roof space.
Would rather have too much, than not enough.
Especially at these prices.
Maybe I can make electricity from moonlight. lol

laugh but I make power even when its raining... granted not nearly as much but I have seen from .8kw-1.5kw of rainy cloudy day output for 7.2kw of panels. obviously that depends upon the cloud cover and and lot of other conditions but with 25kw you are going too make something almost all the time. i have mine setup so that 1.8kw is facing west to lengthen out the solar day the other 5.4kw faces south and has tilting panels to maximize production.

 

[copec]

100 Kwh is a really large bank, and will run your house for a long time even if you are a power hog. but you will need a large array to keep them charged if you are running them hard. say you get 4 hours of good solar per day, you would need at least 20-25 kw of solar just to charge them and run most of your house at the same time. (these are off the cuff numbers). but if you can afford that big of a battery bank then the peripherals are not that bad as the costs are coming down daily. I bought used panels that were 5 y/o or newer and have 7.2kw here in japan the panels alone would be about 40K usd new, but I spent less than 4k on used panels that were all top tier used <5 years old and removed from houses due to upgrades/new construction etc. etc. Not knowing the costs of panels in your area I cant speak on the cost, but I think if you are diligent you can do it reasonably priced.

There are like million homes in the countryside of Japan for sale right now. I would love to fix one up. I’m a countryside person

I could only fit 12kw of panels on my roof, but I’m working towards a 100kwh battery by making second-life battery packs - so that I could carefully operate indefinitely without power/gas if I had to, plus I would be cycling the battery so little on a daily basis it would last a very long time.

 

[copec]

I came across this system recently: https://www.oekofen.com/en-gb/myenergy365/

It’s a mostly typical wood-pellet burning boiler, but with a sterling engine option that generates ~750W electrical from the flu heat.

 

[Swing]

Might look into stored hot water. Cheaper than batteries at least in the states. 1 50gal water heater is about $600 new or less if scratch and dent. Maybe $700 for hybrid with rebates or $1300 full price...scratch and dent can be half the price. 50 gal stored water is about 8 kwhr.
I like the idea for domestic hot water but also for supplemental heating. The hybrid hot water heater systems are so cheap relatively speaking it can be a poor man's equivalent to geothermal if you have a large basement. The cold air output sinks quickly and hits the concrete floor at 60deg F which warms it to 60F almost immediately as it covers the large surface area. A smaller basement may not be as good in that respect and could steal some of the house heat. I've been using one and this is the effect I've seen but I have a large basement about 2100ft2.

Yes I am actively working on a product, basically just an electric boiler, but one that makes it easier for a user to store excess energy in there.
And heated in two stages. So half can be always ready for hot water, and the other part is for extra demand.
Lot of technical people, like on this site, might be able to build it themselves, but it should be accessible and easy for an average user. This is al in Europe by the way.

For myself, I cannot fit huge boilers, we built a small house. I will put 100 liters in though, which is enough for us. And instead of having it always have hot water ready, but just by the end of the day, makes a huge difference in solar power usage.

 

[HarryN]

Yes I am actively working on a product, basically just an electric boiler, but one that makes it easier for a user to store excess energy in there.
And heated in two stages. So half can be always ready for hot water, and the other part is for extra demand.
Lot of technical people, like on this site, might be able to build it themselves, but it should be accessible and easy for an average user. This is al in Europe by the way.

For myself, I cannot fit huge boilers, we built a small house. I will put 100 liters in though, which is enough for us. And instead of having it always have hot water ready, but just by the end of the day, makes a huge difference in solar power usage.

Sounds like a great idea.

One of the challenges of using water as thermal storage is that when it is hot - it kills off bacteria, but when it is "warm", it can actually enhance the growth rate of bacteria quite a bit.

Back in the 1970s there was quite a bit of activity studying solar-thermal type systems and as a middle schooler I did a small hobby project using it. At that time, rocks were one of the better ways to store the relatively low temperature heat. Another was to use the phase change of wax.

 

[Swing]

@HarryN yes legionella is the main reason of concern. But you can even put some more intelligence into these desinfection runs. Not needing them when the boiler was very cold (no growth) or just do this run when you are already relatively high in temperature.
All better than my previous house, which just heat the huge boiler up to 60 degrees C on a fixed day, even though it had been way over 60 degrees the day before.

I had solar thermal collectors before. And I like them. But for simplicity I went with all electric, and treating the electric boiler as just another battery.

Stone is much better for really high temperature projects. However, that requires a huge insulation layer, and thus requiring lots of space.
For me, it is not worth it, since I am only short 1000kWh, the installation will be too big.

 

[houseofancients]

@HarryN yes legionella is the main reason of concern. But you can even put some more intelligence into these desinfection runs. Not needing them when the boiler was very cold (no growth) or just do this run when you are already relatively high in temperature.
All better than my previous house, which just heat the huge boiler up to 60 degrees C on a fixed day, even though it had been way over 60 degrees the day before.

I had solar thermal collectors before. And I like them. But for simplicity I went with all electric, and treating the electric boiler as just another battery.

Stone is much better for really high temperature projects. However, that requires a huge insulation layer, and thus requiring lots of space.
For me, it is not worth it, since I am only short 1000kWh, the installation will be too big.

seems to me it would be a 2 stage system.
once the water get above 55c , all bacteria are killed.
i read somewhere if that temp is reach once a week, that would be fine.

 

[efficientPV]

The big difference is between treated municipal water and something just taken out of the ground.. Legionella is everywhere and we are exposed to it daily. Plenty of chances for it to grow in any home system. And yet we don't hear about it.

 

[Swing]

Well, rainwater can be legionella free. If it is not from a green roof or not too many trees and falling leaves etc.

Every once in a while legionella pops up in the news, claiming a few victims. It is rare, but you have to take precautions.
However for a small boiler at home it is typical used enough that no legionella build up will occur.

 

[efficientPV]

I really doubt that. Rain forms on dust and all the dirt around you has it. Wear a petri dish around your neck and just see how much Legionella is picked up. I had a girlfriend who had rainwater. Every glass had stuff floating in it. Never ate or drank anything from the tap. That didn't last long. I do have some health standards.

 

[Zwy]

I really doubt that. Rain forms on dust and all the dirt around you has it. Wear a petri dish around your neck and just see how much Legionella is picked up. I had a girlfriend who had rainwater. Every glass had stuff floating in it. Never ate or drank anything from the tap. That didn't last long. I do have some health standards.

 

[Daddy Tanuki]

If you run a food grade heat exchanger system the threat of bacteria is greatly reduced one tank being the heated can run whatever temp you like only the secondary loop needs to hit bacteria/virus killing levels. If it is a non potable situation the risks are once again reduced

 

[Zwy]

Well, rainwater can be legionella free. If it is not from a green roof or not too many trees and falling leaves etc.

Every once in a while legionella pops up in the news, claiming a few victims. It is rare, but you have to take precautions.
However for a small boiler at home it is typical used enough that no legionella build up will occur.

I run pure water thru my shop boiler, radiant floor heat. Have for years, closed loop system. Water is from my well. Yes, it has an anti flow back valve.

I've never seen the boiler over 135F.

 

[efficientPV]

Yes I am actively working on a product, basically just an electric boiler, but one that makes it easier for a user to store excess energy in there.
And heated in two stages. So half can be always ready for hot water, and the other part is for extra demand.
Lot of technical people, like on this site, might be able to build it themselves, but it should be accessible and easy for an average user. This is al in Europe by the way.

For myself, I cannot fit huge boilers, we built a small house. I will put 100 liters in though, which is enough for us. And instead of having it always have hot water ready, but just by the end of the day, makes a huge difference in solar power usage.

Lots of luck on your project. Stratified water systems are starting to take hold and as you can see there is still resistance to the idea. Europe with higher energy prices always leads the way in efficiency.

 

[Eastgip]

I used to heat all my house only with gas central heating, now that I use for that my solar panels as well because it is more affordable for me. I also have changed the old radiators, because they are less energy effective, of course, they were cheaper, but they force me to turn the heating on at a higher temperature, and in a long term it is very expensive. So I bought new ones from the radiator outlet and the house warms up much faster.

 

[GMP]

A couple of suggestions for use of excess solar for heating:
a) You mention having a solar diverter. These are on a dedicated circuit to an immersion heater to heat water. However they will work on any device that has a standard thermostat, for example an electric convector heater. I think some solar diverters can cater for more than one device being attached. The alternative would be to have a switch so that the diverter worked either with your immersion heater or for a convector heater.
b) You could consider getting a portable air conditioner. These are from about 1kw input upwards. (but unlike the above they have to have the full wattage, not just the spare excess that a solar diverer supplies) Portable AC units like fixed AC can be used both for cooling and heating. They are less efficient than fixed AC but still produce over double the input - i.e. for every 1kw they produce £2k of heating. Plus, if like me, you have somewhere that tends to overheat in very sunny weather, the 'free' AC cooling is very handy.