Super Simple Solar Energy

A classic illustration of not understanding the original requirement:

"So another idea is using solar panels in a super simple way. Not to replace electricity, but to provide a little heat to the basement. So it would just be solar panels connected to a resistive load. No battery storage, no inverter, no temperature control."

Have you read and understood the original requirement?:

"So another idea is using solar panels in a super simple way. Not to replace electricity, but to provide a little heat to the basement. So it would just be solar panels connected to a resistive load. No battery storage, no inverter, no temperature control."

Have you read and understood the original requirement?:

"So another idea is using solar panels in a super simple way. Not to replace electricity, but to provide a little heat to the basement. So it would just be solar panels connected to a resistive load. No battery storage, no inverter, no temperature control."

I interpret this as just connecting a resistor to the panel and nothing else.

Have you read and understood the original requirement?:

"So another idea is using solar panels in a super simple way. Not to replace electricity, but to provide a little heat to the basement. So it would just be solar panels connected to a resistive load. No battery storage, no inverter, no temperature control."

It is super simple. It may be disappointing when he is done, but that is not the question, is it?

Can you ground mount and just use a hot air collector and maybe a small Photovoltaic to run a fan to move the hot air down to the basement. Something in here, >

Mikek

icient. And plumbing solar collectors is a lot more work. Here ( Delawar e ) you either have to drain the system at night so it does not freeze or have an expansion tank to so you can use antifreeze .

How is the need for an expansion tank dependent on whether the fluid is water or a mix of water and antifreeze?

close to the optimum temperature. Only above ground walls are insulated.

Only if you think ~55F is the optimum temperature. Otherwise a basement is like having an uninsulated living space when it's 55F outside. Actually it's worse than that, because when it's 55F outside, sunlight is a big help in warming the living space. In the basement you don't have that. IMO, it most of the US if you're going to finish the basement and use it as living space, you'd be nuts not to insulate it.

rd to apply" is directly in contradiction of the OP who is looking for a si mple solution. In this case I think PV solar may be an easy approach. The only issue is whether it is cost effective or not.

We've outlined why a spec that lacks, or even forbids, an MPPT component, would work poorly. But let's see how it could work if we allow one simple addition, a 300W boost converter. The I-V curves for my Hyundai HiS-S280RG 280W solar panels show an MPPT point near 32 volts. We can add a 15A CCM boost converter, having an enable with hysteresis, set to say 28 to 30V, and an input capacitor, say 2200uF 63V (dV/dt=I/C, 2V/300us = 15A/2200uF). The boost converter will run when the cap voltage is above 30V, and continues until it drops below 28V. If the boost is set for 120Vdc output, and intermittently powers a 500W heater, most all the available solar panel energy will go into the heater.

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PPT) load. If you try to draw a fixed amount of power and the solar cell c an't deliver that, the resulting power provided goes down a lot more than i t should. Draw too much current and the voltage drops disproportionately.

voltage and for any given lighting condition you won't get optimum power. So in reality you need a MPPT load device instead. Not hard conceptually. It's basically a switching regulator but the thing being controlled is po wer to the load rather than voltage or current. Use a low resistance load and a standard buck topology can be used. A small MCU can measure the volt age and current into the load and dither it to find the optimum power point .

That was my original thought. Did not know there were cheap MPPT's on the market. That is what is good about SED. One learns things.

Dan

Why not just heat the air and move it where you want it. Assuming that won't be far. Mikek

I have two electric heaters in the basement already. They are also super si mple. They are made from electric furnace heating elements mounted so the air flow is up. They will work fine with convection air flow but each has a 10 inch 240 volt industrial fan which helps to spread the heat around. One is at each end of the basement and plugs in a receptacle for a machine tool. With a single heater running it takes about 20 minutes to have the ba sement comfortable in Jan.

Dan

One poster here said MPPT will not work with a resistive load. I'm not sure about that so I don't believe it for now.

If you are trying for maximum effectiveness, you should use a maximum current seeking device. It will work for either battery or resistive loads. It is very simple. For a battery, you want maximum current to get it charged. For a resistor, you want maximum current to get maximum power.

MPPT is not a mysterious panacea.

If cost doesn't matter, use a roof full of solar panels inefficiently.

I like Win's link:

"Solar space heating can be 25 or more times more cost effective than solar electric (PV) systems"

but there no limit on how inefficient a PV heating system can be made.

So you have not read the original requirements.

Heating the air does not remove the moisture. The water content in the air stays constant, just the *relative* humidity goes down. To remove the moisture you must cool the air to below the dew point. You can then heat the air if needed.

ter

micro inverter + $10 heater.

connect MC4 to micro inverter, plug inverter output into outdoor light or A /C outlet, plug in heater in basement.

The heater will be a fixed resistance. At some input power level (most lik ely well above the actual solar panel output level) the inverter will be ab le to output power but the heater will be the limiter since it draws a fixe d power at a given voltage level. At power levels below that the inverter will either output a lower voltage, or more likely it will simply shut down for safety purposes since that would essentially be outside it's design pa rameters.

The combination of actually getting the maximum power available from the pa nel delivered to the load will only happen on some lucky day when all the p lanets are aligned.

The bottom line is a variable load is needed or possibly an MPPT that will provide that maximum power level to a fixed resistance load. An inverter i s not the right tool for the job.

So what does the inverter do when the input power is less than the load wou ld draw at the output voltage? From the data sheet for a microinverter...

Nominal (L-L) voltage/range 240V/211?264V 208V/183?229V

For the output power to match the input power the output voltage has to ro am with the input power. That ain't happening with an inverter designed to supply AC to the line.

To get the max power from the solar panels to the load the power at the loa d has to vary. With a resistive load this means a variable voltage. What type of DC/DC or DC/AC converters do that?

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urrent up to the knee of the curve where the max voltage is approached and the current drops off dramatically. At that point it is constant voltage.

That's not what "constant current" means. Constant current means the same current independent of load, in other words, the voltage varies. What you have described is just ohms law.

Solar cells have a range that is constant current (or nearly so) and a rang e that is constant voltage (or nearly so) and a knee that joins the two. F orget about your labels and consider that curve. The knee is where the max imum power is obtained.

ly. Maximum power is at a point on the knee between the two.

So? Consider my posts to be information to the OP if you don't like what t hey say.

Why would they need to be on the roof. At my place I would consider making them into an awning. Putting them on a roof means complications when the roof needs replacing.