Super Simple Solar Energy

r's house was set to something like that by an external dial. I changed it

ics of a heat pump aren't significantly worse at lower temperatures. It is simply that the capacity is reduced because it is having to push the heat further uphill to the inside, so less heat is actually moved. But it is st ill better than resistive heat. When it won't keep the house warm enough, kick in the back up heat, but no reason to turn off the heat pump... well i f your back up is straight electric anyway.

n't the reason.

and

hey are close to the optimum temperature. Only above ground walls are insu lated.

ment

ht

ement

iving spaces and they are not heated. If they are, then they are generally insulated in colder climates.

That's not what I was talking about. I guess I was generalizing too much. While I think a 7 foot deep frost in Vermont is a bit overly dramatic, the 55 degree temperature is around here. In places like Vermont the undergro und temp is around mid 40s, so likely the full basement wall is insulated. If the freeze line really did get to 7 foot down, there would be a lot of frozen well pipes every year. They have to come up enough to enter the hou se at some point.

winter, it feels really nice in the summer. So insulating the underground portion of the wall will give a savings while heating at the expense of req

omise between the two.

And Solar Collectors are one example of this. Seems like a good project, b ut it also seems like a bunch of work. So another idea is using solar pane ls in a super simple way. Not to replace electricity, but to provide a lit tle heat to the basement. So it would just be solar panels connected to a resistive load. No battery storage, no inverter, no temperature control.

cells for about $100. So could make 4 panels , 2 feet by 3 feet to hold 24 solar cells on each panel. Maybe run lines for each panel to the basemen t.

Even if it weren't, the losses would end up as... heat.

I suppose at some point a resistor will give off light that isn't IR and so will be slightly less than 100% efficient at producing heat. lol

Not really. It looks bad if you are looking at a commercial design

But, this is for Space, so what a normal converter does not have is added:

Input current sense Input current trip MOSFET Output current sense Output current trip MOSFET Control and monitoring system Old bipolar PWM controller (at that time no FET UCCxxxx controller was approved for space) Filter for ultra low noise

All that adds up

Cheers

Klaus

If all of the extra features you mentioned are a sort of sunk cost in terms of efficiency, then perhaps improving the efficiency by 0.1% would have been just as hard as improving the finding of the maximum power point by 0.1% - in other words, if the incremental effort per incremental watt got out of it by improving efficiency is about the same as the incremental effort to per incremental watt out due to finding the maximum power point more accurately, then the effort is sensibly allocated.

It is a way more appropriate solution to the problem than the DIY solar PV approach and would be able to supply more heat than a puny 300W.

I found the same thing. The panel gets hot so it gets closer to the MPP when attached to a battery. Of course that was in a warm ambient and at peak insolation.

The accuracy of 0.3% is cheap, just takes some thought. As I wrote, much lower than 1 USD

Increasing efficiency of the converter is costly, cannot be compared

Cheers

Klaus

You are absolutely correct. But my problem with that approach is that I ne ver get around to building the better system. I may not get around to maki ng a PV system. but it seems like it would be a lot less work. And I think a puny 300 watts for about 3 hours a day would be enough to make the base ment a pleasant place.

Maybe I should make a 300 watt heater and run it off a timers and see if t hat is enough. ( or just use heater that I already have and adjust the tim es so the heater provides one KWH per day.

Dan

Dan

n the

move

n then

ectly accurate.

like NT not understanding what is being said and.

d, dry air is then passed over the other end of the heat-pump circuit to wa rm it up again (and recondense the refrigerant that little bit faster).

s lower its RH.

properties, which is on average lower in moisture content, and which then drops RH as it warms.

indoor air, or warmer or cooler. Swapping air with the outside world is ve ntilation.

ism by which the great majority of houses are dehumidified.

you are getting worried by damp patches on the walls, dehumidifiers attack the problem directly. NT is in evasive mode here.

d, dry

dehumidifiers don't use chilling at all. Nor do box-of-salt type ones, eve n though they're of minimal use.

but some hardware stores cater for people with little money and even less s ense. As NT admits, they don't work well enough to be of much use, and they certainly aren't cost effective.

erated by heating, but strictly for tiny volumes of air.

rely an invitation to enter into his spiral of madness. I'm not interested in doing so & don't care what he has to say.

lpful pontification.

Lol. And desiccant wheel dehumidifiers work just fine.

I don't understand that circuit very well. I see two comparators, one comparing the SA voltage with a sampled fraction of same, the other the SA current with a sampled fraction of that current. The comparator outputs drive an SR FF, the crossed outputs of which drive the S/H switches and an integrator. The integrator controls the PWM input of the power converter.

How does this converge on the maximum power point? Does it rely on the charge of the hold capacitors drifting in some specific way?

Thanks, Jeroen Belleman

And what do you do with the desiccant when it is saturated with water?

Do they become humidifiers, when (if) the air otherwise becomes dry again?

When you look at the I/V curve for the solar array, you find that the maximum power point is at the curvature, where the slope is 45 degrees

To if you sample the voltage, let the converter ramp the current up linearly, until the voltage has decreased say 1%

You change direction on the 1% decrease, so now you sample current, ramp the current down, and change direction again at 1% degrease

You find that you are then operating in the MPPT point

The flipflop is just there to change the direction, and trigger the S/H circuit for either the voltage or current part

Cheers

Klaus

Cheers

Klaus

It's also a lot more work for a DIY project. A LOT more work.

never get around to building the better system. I may not get around to ma king a PV system. but it seems like it would be a lot less work. And I thi nk a puny 300 watts for about 3 hours a day would be enough to make the ba sement a pleasant place.

that is enough. ( or just use heater that I already have and adjust the t imes so the heater provides one KWH per day.

I think it is a mistake to believe 300 watts will do much in your basement. I have a house that is currently vacant. A 1400 watt heater barely makes a difference in a 40x25 foot basement. I'm just trying to keep the pipes from freezing and it barely does that. In fact, I might need to turn it on .

You definitely should test it first. My guess is that a 300W heater won't even be noticeable unless your basement is incredibly well insulated. I'd guess you need at least 1kW and a few hours to make any noticeable change. A 3kW fan heater would definitely make a difference.

Three 100W bulbs in an old empty oil drum will do it for a test.

As a ball park figure to get 1C rise every 10 minutes in our village hall 12mx6mx3m requires about 16kW of active air heating. The walls are solid Victorian engineering brick so not dissimilar to concrete.

It's a good approximation to the situation here in Seattle. Very useful, any pipes in the basement are not worth worrying about, they'll never freeze.

Basement insulation is typically a few feet down from ground level, then... stops. If the basement is climate controlled, the floor and much of the wall is just NOT capable of large heat/cooling leak, because the tons of subsoil and rock are not very (thermally) connected to the local weather. High heat-flow resistance, and large heat capacity, makes the familiar RC filter...

For basement heating, it might suffice to locate the converter in the basement.