frank li

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since Mar 21, 2016
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Recent posts by frank li

Generally the slow pump has a higher suction capability than the standard pump. The standard will deliver a higher rate. Power consumption is lower and gallons per watt higher if i remember also.
3 days ago

Nicola Woelfe wrote:Hello all!,

A belated but warm thank you to everyone for responding.   I am sorely tempted to purchase the Dankoff Slowpump 1322-24 24VDC surface pump... even if it doesn't work for the full 15-20 years, I will have saved money if it works for more than 7 years at the rate the shurflo pumps are failing on me.  

I would love to hear why people recommend a slowpump over dankoff's other models.  Does anyone have a recommended source for reading more about those pumps?  Most of what I find about them is from people who sell them which is not the way I like things when I go to make a big purchase.  

Thank you so much for your help!


This pump was installed a year and a half ago and is the 48v model. Delivery rate was not adequate for multiple taps in a large home to run at once, but plenty for backup to city water from a motorized hand pump well and 400 gallon storage tank. Great dc pumps.

3 days ago

Johan Thorbecke wrote:More than a grand for a pool pump, yikes.

Yes, pools are expensive to own and operate. They are a luxury.

Gallons per hour and gallons per watt equal performance and these will direct drive with the linear current booster/controller.
5 days ago

Eric Hanson wrote:S Bengi,

For high temperature heat storage and heat transfer, molten salts are very hard to beat.  I am curious about the overall efficiency of this system as each step in the process loses a portion of the overall energy so I am intellectually interested in how much energy the system delivers compared to how much it receives.  Also, over time the hot side will cool over time and the cold side will warm.  But over short time spans (such as overnight heat storage, maybe even a couple of days depending on power needs and circumstances) this setup could have real potential.

Extremely cool idea though.  I did my masters research in the history of energy and I am starting to contemplate going for my PhD in the history of energy and by now I have an almost unhealthy fascination with all things energy.  I now see energy everywhere.  I see it in my coffee in the morning, sunshine streaming into my windows in the day, my Christmas tree—EVERYTHING!  I especially like new forms, sources, methods of generating and storing energy.

If I don’t stop now, I will ramble on incessantly so I will conclude by saying again, very cool and you have piqued my interest.


Tesla, im sure you know had much the same observation. You better quit now or you will be washing your hands 33 times in a row every 9th time and feeding pigeons because they are your only friends!
2 weeks ago
Sounds like the Sun Danzer has proven its value. When refrigeration was not possible it was producing ice to aid in heat removal! A matching fridge would likely end your issues with a slightly improved pv system.

If you ran 4 golf car batteries you would have the benefit of the paralleled sets (and the detriments) and would always have a 12v set to use if a battery failed.

Marine batteries cost as much or more to run. I say more because they will wear out quicker and do not have the capacity ah for ah (name plate) especially at deeper dod at higher rates and over as many cycles.

Dissapointment is a type of cost associated with alternatives also.

With the numbers and costs given for thermostat modified deep freezers used for refrigeration, they must be considered. You have.

We have a challenging pv site. About 80 percent solar window, 3.75 hours peak average yearly, 1.2 hours peak winter average. No generator allowed (pv purist, self limitation).

With 1640W pv and 440Ah/24V comprising the main system we discontinue refrigeration amd freezer operation about late october or early november and use an outdoor storage for frozen foods and a large cooler brought in and out to moderate temps for produce. Leftovers go in a cabinet on the porch to freeze overnight. This lasts til almost april some years with loss of reliable freeze in late march.

We have 3400 more Watts pv in the garage waiting for upgrades, but even doubling battery capacity would likely not allow absolute reliable deep freezer and conventional refrigerator/freezer operation year round without a dedicated and or auxilliary battery system or backup generator.

I have recorded up to 14 days consecutive days of almost no charging at least once a winter. Our system will do 10 with conservation and 6 without, at 0%-5% array input over 8 or so hours. 14 days requires turning off the inverter when we are done using it and a transition to another system.

There is an auxilliary system used for communications radio, personal battery charging and backup lighting (male to male extension cord gets it done as we are wired 120v only) and coffe grinding. It also runs the dhw boiler circulator and has its own 200w inverter, 90Ah battery, 15a MPPT CC, 224W module, etc.

This is used for maintenance and backup.

435Ah/48V and 3600W PV is the cure at my location and usage profile as i have most of the stuff laying about at any given time, but our fridge is not high performance and off grid pv requires high performance/high efficiency and so refrigeration could likely be a non issue with a $2600-$4500 investment in proper appliances.

With a year worth of wild game meat on the line and a set of batteries, is not the most extreme thing to spend system budget on.

We keep it on grid and off site for now, its an evil secret to our off grid living, shhhh!

Dont give up on lead acid. It is simple, robust and state of the art technology as opposed to "state of the finnicky coin flip" and your system will function without dissapointment and with longevity if you dont place unrealistic demands on it.
2 weeks ago

Dillon Nichols wrote:You may want to be a bit more specific, what size, chemistry, and application do you have in mind?

I have a set of 8 Sinopoly 400AH LiFePO4 cells, but have only had them 3 months; much too early to say that I'm happy.

Getting satisfactory connections has been a bit problematic. The bus bars as included were of a length that only worked for half the connections; the cells are 'packaged' in pairs with metal strapping, and bus bars only fit the strapped pairs, not between the pairs.

I made my own bars for the other connections. So far things are working fine after retorquing twice, but as I am still waiting on my inverters there has never been a heavy load to tax the connections.

Documentation was very sparse. Warching voltages approaching full charge, a couple cells are obviously the weakest link.

I bought through a localish reseller, so can't comment on the direct purchase experience.

Evtv/Ev motor verks store has a locking fastener system to combat that exact issue.

Not sure if they sell just the washers. NordLock.

4 weeks ago
The best thing for the installation is likely going to be a high head circulator (pv drive) a tilt evaluation and some plumbing routing possible. I cant see whats going on with the circuits. In that case everything can be close and may not require the tower unless its for something else. Brings the question of heat exchanger/no HE for dhw.

If you want to thermosyphon, i would re work the collectors, assuming they are diy or source parallel manifold collectors. It needs risers and manifolds.

Imagine a ladder on its side, except the rungs are 6-10 feet long and the beams 3-4 feet. When fluid is circulated and fed and returned from diagonally opposed corners it will equalize flow through the risers and other parallel collectors of the same dimensions.

The same thing is done in electronics, batteries, etc.

We tilt to face toward the sun and rotate on that plane for thermosyphon and drain back placing the outlet at the highest corner of the collector/row.

1 month ago

julian Gerona wrote:

Orin Raichart wrote:Both Debi and Frank are right on. There are only two items I didn't notice in their posts:
-for convection flow to work you need atleast 18 inches or 45.72cm height difference (which you will get when you angle the collectors);
-many hot water systems using convection flow will not work if there is an air pocket trapped in the pipes/collectors connected to your tank.

Good luck!

I agree I dont see a thermosiphon here. its natural convection flow. thermosiphon works by alternately heating and cooling a vessel full of air. this advice is correct except that height difference does no determine angle of inclination. Ideally your angle should follow the sun but not less done 30 degrees.

I dont think Orin meant that determined angle, only that it would get the height difference from a tilt.

In my mind there is that difference and it doesnt matter. The floor of the storage tank located higher than the collector output is the key to a tank full of heated water and at a decent rate. It could be done with a tank floor at collector input height and a tall tank, but storage capacity would suffer, collector efficiency should drop.
Then again the difference could be small enough to do anyway or i could be off and you wouldnt loose much as long as the tank floor is no lower than the collector input.

It needs a check valve a swing check horizontal if reverse flow is an issue and generally anyway. The collector could be insulated but difference in temp is power, flow if its arranged appropriately and in forward and reverse.

Sites vary and delta t is a double edge.
1 month ago