Author Topic: Digital Maximum Power Point Tracking no DC-DC conversion.  (Read 3326 times)

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Offline dirtcooker

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Re: Digital Maximum Power Point Tracking no DC-DC conversion.
« Reply #25 on: June 12, 2019, 02:46:10 am »
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Heat pipe/evacuated glass tube solar heaters can be purchased directly from the factory in china for about 1/4 the price you have listed in your presentation. See http://www.lucky-energy.com/ for example. Also, solar hot water is at least 4x more efficient in terms of watts/m**2 than PV, so you need a lot less space on your roof, and the system will provide domestic hot water as well. If your primary purpose is to heat, solar hot water is definitely the way to go, especially if you have PEX tubing in a concrete floor to store and radiate heat.
Alternately, you could run a heat pump with PV generated electricity.

You need to consider shipping from China and import taxes. On top of that the lucky energy is a fitting name as you will be lucky to have all tubes working and not broken during shipping and quality is unknown. You can also find solar PV panels in China at much lower price than in my presentation but again shipping import tax and quality may get you in the same spot or worse.
As you seen in my presentation is just a 2.5x factor not 4x when it comes to space needed as solar vacuum tubes have some spacing they are not flat collectors. So yes as mentioned there PV panels for same output power will take about 2.5x more space but most of the time that is not a problem.
Solar thermal will be more expensive no matther how you will try to do that and less reliable. I was fairly generous with thermal solar there still it was not even close.
Heat pump has the same problem (way to expensive to be considered).

Your supplier, nlsolarheating/solartubs, imports them from China and charges you 4x the cost.
https://www.solarthermalworld.org/content/china-sunrain-group-goes-public
I imported a system from lucky, the quality is very good. Have a look at the article I referenced from "International Journal of Photoenergy"
Of course, if you primarily need electricity then you could put up extra panels and run a heat pump. I don't know about Canada, but in USA I can buy a 4 ton air source heat pump for $2k. In your climate though you would probably need a ground source rather than air heat exchanger, which will cost more.
« Last Edit: June 12, 2019, 03:18:57 am by dirtcooker »
When all is said and done, much more is said than done
 

Offline electrodacus

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    • electrodacus
Re: Digital Maximum Power Point Tracking no DC-DC conversion.
« Reply #26 on: June 12, 2019, 03:28:22 am »
Your supplier, nlsolarheating/solartubs, imports them from China and charges you 4x the cost. I imported a system from lucky, the quality is very good. Have a look at the article I referenced from "International Journal of Photoenergy"
Of course, if you primarily need electricity then you could put up extra panels and run a heat pump. I don't know about Canada, but in USA I can buy a 4 ton air source heat pump for $2k. In your climate though you would probably need a ground source rather than air heat exchanger, which will cost more.

I'm sure the supplier in Canada orders them from China but in high volume probably full container and so it gets a much better price not to mention lower shipping cost than I will pay for just a few tubes.
And yes they will have some profit margins but likely they tested multiple China supplier and got the best one (I can only test one).
Still even ignoring the cost of the thermal solar collectors thermal solar costs more and last much less as there are thermally insulated pipes and high temperature water pumps most will requite maintenance and a few replacements over 25 to 35 years.
As I also need electricity it allows me to have a much smaller LiFePO4 battery as I can use the large heating PV array to charge the battery fully even in worst overcast days that battery saving alone is worth more than thermal solar collectors.
Air to air heat pump will not work here as is way to cold in winter and geothermal is just way to expensive. Also a heat pump will not be able to recover the investment even $2000 over the usable life at just 2 cent/kWh that is the cost of energy from solar PV. From grid with price of 15 to 20 cent/kWh the heat pump may be able to recover the investment but not from 2 cent/kWh as there will not be enough saving to recover that $2000 initial investment.
Plus you need a much larger battery and larger inverter to run that heat pump and you need pex and pump as you can not heat the air (you can but then the battery needs to be huge).
There is just no way to make savings in my installation by replacing anything with a heatpump even ignoring the lower temperature here.
Total cost is 12k most of that is for solar PV panels. You can reduce the size of the PV array to buy the heatpump but then you need to also increase the battery size and inverter thus making it way more expensive. You need to think about the entire system.


My house needs about 1000kWh for heating in January (coldest month here) so you can design a system capable to do that and cost less than the one I designed. If you try to do that you will understand that adding a heat pump is significantly more expensive.
« Last Edit: June 12, 2019, 03:34:22 am by electrodacus »
 


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