If solar array I used for winter is no longer needed should I cover them up?

[pierremontagne]

I 'overpanelled' by about 900W to feed my 100ah lifepo4 battery over winter but now we are in March I will probably be fine just with the 300W until september or so.

So should I cover of this second array of 900W? I have tried to think of useful things to use it for but can't think of any. Maybe water distillation which drinks lots of electricity but those are expensive to buy unless I find a DIY way to make it more affordably.

Does it make a difference to the panels if they are in full sunlight but not plugged in to anything vs being covered by a tarp?

[Psi]

Other than not getting dirty with bird crap that you'll need to clean off later I cant see a reason to cover them up.
Maybe protection from hail storms I guess, if you get those.

Obviously if you do cover any up you need to make sure you're covering an entire series string and not only some in a series string, or you will mess things up and affect the uncovered ones.


If you want something to do with the extra power here's a few ideas with varying levels of capital needed
- Bitcoin miners
- Hot water heating
- Indoor LED grow lights/pump for some indoor hydroponics or just normal style planting and grow some food. There's a few fruit/veg options if you have bright indoor light available for free.
- Install a heatpump.

[Kleinstein]

Most panels have no real issues with being in the sun. It is mainly thin film (especially a-Si) cells that show significant aging from exposure to the sum. Normal panels are made for 25 years+ of operation. The part aging is likely more the glue than the actual cells. Changes are the wear on a tarp would be larger and the temperature seen by the panels may not be much lower.

[TUMEMBER]

Buy a few square meters of 2 cm thick Styrofoam insulation, cover it with a "thermal emergency blanket" (a cheap substitute for aluminum foil for baking), and place it on the panels. Secure it. On the other hand, why not use this free energy to heat water in boilers for "bathing and washing pots"?

[brucehoult]

They might get pretty hot under a tarp, which isn't good for them.  Being in the sun and not connected, and so having Voc all the time, is also not good for them.

I think probably the best thing for them (if you don't want to connect them to a proper MPPT for some reason) would be to connect them to a ~900W heater of the same voltage as the array's maximum power voltage (which you didn't tell us). This will both remove heat from the panels and prevent them sitting at Voc. They last the longest when working as they are designed to.

[paulca]

They might get pretty hot under a tarp, which isn't good for them.  Being in the sun and not connected, and so having Voc all the time, is also not good for them.

Indeed.  Also being under a tarp is often worse as it traps moisture and humidity in and in my locale it will collect dew in the mornings by the litre on both the inside and the outside.  100% humidity in Ireland is the normal.  It just means it's either raining, has just rained or is just about to rain.  BTW  It's why tents have 2 layers.  Before they had 2 layers, the old canvas tents needed to be "aired" once a day, the had "skirts" that lifted up and tied back to open the whole tent to the breeze.

[pierremontagne]

Other than not getting dirty with bird crap that you'll need to clean off later I cant see a reason to cover them up.
Maybe protection from hail storms I guess, if you get those.

Obviously if you do cover any up you need to make sure you're covering an entire series string and not only some in a series string, or you will mess things up and affect the uncovered ones.


If you want something to do with the extra power here's a few ideas with varying levels of capital needed
- Bitcoin miners
- Hot water heating
- Indoor LED grow lights/pump for some indoor hydroponics or just normal style planting and grow some food. There's a few fruit/veg options if you have bright indoor light available for free.
- Install a heatpump.

None of those appeal to my lifestyle. I am doing off-grid living. Oh now I look at it the hydroponics is interesting as I have a long term goal of self sufficient food and had also thought of this idea to use the excess before to grow perhaps some exotics that don't grow in the uk. Maybe mango I read that is extremely quick growing under the right conditions but don't know if it would work. I also have loads to do already anyway just with the normal growing so doubt I would want to make that a priority. I would sooner use it for water collection somehow as that is a priority and water is scarce in summer. There was drought last year.

[pierremontagne]

Most panels have no real issues with being in the sun. It is mainly thin film (especially a-Si) cells that show significant aging from exposure to the sum. Normal panels are made for 25 years+ of operation. The part aging is likely more the glue than the actual cells. Changes are the wear on a tarp would be larger and the temperature seen by the panels may not be much lower.

You mean in the sun and unplugged? I want to unplug as if they are not needed to keep the battery topped then it is easier since I have to unplug and plug the lead to my van which is an anderson connector under the vehicle which is a bit fiddle to get at. Worth it of course when I need the extra power but otherwise it is an unneeded inconvenience.

[pierremontagne]

Buy a few square meters of 2 cm thick Styrofoam insulation, cover it with a "thermal emergency blanket" (a cheap substitute for aluminum foil for baking), and place it on the panels. Secure it. On the other hand, why not use this free energy to heat water in boilers for "bathing and washing pots"?

Is that for a water distiller or just to cover them? was not clear what you meant there. I dont need hot water. I do fine with just boiling water on my stovetop if I want hot. I had thought of using an electric cooker which of course gulps electric to have a clean energy source for cooking but they only run on AC except a couple of chinese exceptions I saw, and have avoided AC due to being scared of it compared to DC in terms of safety or is that unnecessary fear? I figured 12V is safer and have avoided AC due to higher volts as relatively more dangerous.

[pierremontagne]

They might get pretty hot under a tarp, which isn't good for them.  Being in the sun and not connected, and so having Voc all the time, is also not good for them.

I think probably the best thing for them (if you don't want to connect them to a proper MPPT for some reason) would be to connect them to a ~900W heater of the same voltage as the array's maximum power voltage (which you didn't tell us). This will both remove heat from the panels and prevent them sitting at Voc. They last the longest when working as they are designed to.

Yea, well as above I prefer not having them connected since I have to manually go under the van to connect and disconnect so if it is just surplus I prefer not have that extra work for nothing. To utilise it on the land somehow would be nice but I didn't think of anything I could really benefit from, except water purification, which I didn't find an affordable way for using it for that. It would be cool if I could somehow use it for that while I had the surplus energy and store the water in large containers for later times when I didn't have the surplus energy.

Another thing I though of is possibly irrigation system and other type of stuff related to growing on the land but not done too much growing wise yet so don't really know what would be beneficial and was trying to just keep it simple first, relying on the weather, before trying to get more complex and know from experience what would benefit.

[pierremontagne]

They might get pretty hot under a tarp, which isn't good for them.  Being in the sun and not connected, and so having Voc all the time, is also not good for them.

Indeed.  Also being under a tarp is often worse as it traps moisture and humidity in and in my locale it will collect dew in the mornings by the litre on both the inside and the outside.  100% humidity in Ireland is the normal.  It just means it's either raining, has just rained or is just about to rain.  BTW  It's why tents have 2 layers.  Before they had 2 layers, the old canvas tents needed to be "aired" once a day, the had "skirts" that lifted up and tied back to open the whole tent to the breeze.

Hmm I didn't think about it being worse. Worse even that unconnected but out in the sun? Well I am in Uk so same type of weather however we had bad drought last year for what seemed like months which you must have experienced too. Not set to rain for about 10 days now so seems to be shaping up to be similar.

That is why I think the energy would be best used for water security somehow, but I don't know how. I have a natural spring but I don't know how to use the panels to purify it in a way that is cost effective. Distillers are like 1 grand and above. Reverse osmosis I looked at and they have hideous waste at like 1 part pure to 4 parts waste  which is awful if you are in a drought. 10 litres pure, which is average what I would use in summer, maybe a bit less but round up, and 40 litres waste would be crazy. Last year not only both my small streams dried up but also the large stream they feed into. I had to walk a couple hundred meters to that stream and take from an ever dwindling pool for a couple of weeks until it finally started raining again.

[brucehoult]

That is why I think the energy would be best used for water security somehow, but I don't know how.

So what about using surplus electricity to extract drinkable water from the air?

https://www.amazon.com/AERstream-Pro-Atmospheric-Water-Generator/dp/B0G1TGMSGD

Any cheap dehumidifier does that, but the water they produce is not regarded as safe to drink as they are not designed with avoiding contamination in mind (you probably could, with additional filtering). But I use water from mine to water the plants, and of course it would be fine for other non-drinking applications.

The "water generator" specs say it uses 200W, but I don't know what the real-world daily water production will be.

I think roughly speaking my dehumidifier (Panasonic F-YCL27N) fills the 5 litre tank about every 2kWh of electricity used (8 hours of continuous running at 250W), so an actual 15 litres per day. That's while operating in a room between 21º C and 24º C at RH of 45%-55% (it has an automatic mode that cycles on and off at around those limits). The headline spec is "up to" 27 litres/day.

So maybe 10 litres per day is actually realistic from the purpose-made water generator, using 4.8kWh of electricity

AC power is easy and safe to manage with a "portable battery generator". I have a Pecron E3600LFP which has 2400W of solar input (I actually have 2640W of panels on mine), a 3kWh internal battery, and 3600W 240V AC output. Cost of the US model is currently $1049, but as usual things are a bit more expensive here in New Zealand or in Europe.

[5U4GB]

Other than not getting dirty with bird crap that you'll need to clean off later I cant see a reason to cover them up.

It also works the other way though, with a tarp over them they'll collect dust and blown-in debris and dead bugs and all sorts of other stuff that rain normally rinses away, so you could end up with a bigger cleanup if they're not exposed to the elements.

[pierremontagne]

That is why I think the energy would be best used for water security somehow, but I don't know how.

So what about using surplus electricity to extract drinkable water from the air?

https://www.amazon.com/AERstream-Pro-Atmospheric-Water-Generator/dp/B0G1TGMSGD

Any cheap dehumidifier does that, but the water they produce is not regarded as safe to drink as they are not designed with avoiding contamination in mind (you probably could, with additional filtering). But I use water from mine to water the plants, and of course it would be fine for other non-drinking applications.

The "water generator" specs say it uses 200W, but I don't know what the real-world daily water production will be.

I think roughly speaking my dehumidifier (Panasonic F-YCL27N) fills the 5 litre tank about every 2kWh of electricity used (8 hours of continuous running at 250W), so an actual 15 litres per day. That's while operating in a room between 21º C and 24º C at RH of 45%-55% (it has an automatic mode that cycles on and off at around those limits). The headline spec is "up to" 27 litres/day.

So maybe 10 litres per day is actually realistic from the purpose-made water generator, using 4.8kWh of electricity

AC power is easy and safe to manage with a "portable battery generator". I have a Pecron E3600LFP which has 2400W of solar input (I actually have 2640W of panels on mine), a 3kWh internal battery, and 3600W 240V AC output. Cost of the US model is currently $1049, but as usual things are a bit more expensive here in New Zealand or in Europe.

Great ideas thanks.

I did actually look at water from the air ideas last year, before I had these panels, just due to it being drought and streams having dried, and didn't see any viable solutions at the time, only some obscure scientific papers about it. Had no idea you could collect it to any meaningful degree with standard dehumidifiers. Maybe obvious for those who have used them before but I haven't. I think it would be fine to do that and then send it through my usual gravity filter which I use for ground water as I imagine the dehumidifier water would probably be even cleaner than the stuff I take from the ground.

This would also have an advantage over the ground stuff in that I am having side effects from the ground water which I am guessing are related to too many minerals in it. I think this because the effects are just the same as when I would take potassium supplements and had to stop. I was looking into rainwater collection for precisely the reason that it is supposed to be naturally distilled which means it contains barely any minerals so I imagine the same would apply for dehumidifier collected water.

As to your suggestion for AC that seems pricy. It would be better just to get an inverter wouldn't it? since I already have the electrical system setup. Btw the Voc of the panels, which I believe you queried earlier, is 73V. Could I use that as AC without even having to convert? I am a noob to that stuff so might be way off but I read a comment before in one of my threads about using the Voc with LED light AC transformers so wondered if similar trick could be applied here. Might be way off, just throwing it out there.

The thing you suggested seems like an all in one thing like a Jackery but seems like it would be a waste for me since I already have all the other equipment, just a case of converting the DC to AC, if indeed I need to. Maybe there are DC dehumidifiers around. I will have a look. They are much more popular than 'distillers' so more likely to have DC options.

[pierremontagne]

Other than not getting dirty with bird crap that you'll need to clean off later I cant see a reason to cover them up.

It also works the other way though, with a tarp over them they'll collect dust and blown-in debris and dead bugs and all sorts of other stuff that rain normally rinses away, so you could end up with a bigger cleanup if they're not exposed to the elements.

Is there any meaningful damage to them being unplugged yet left out in the sun? I could take them in to the woodland in the shade but I rigged a frame for them which I tilted to almost vertical, oh yea that will help avoid crap, due to the winter season being my main interest. I believe I noticed a larger spike early in the mornings once I did this during those lowest apogee weeks. Not conclusive but I think so.

I'm thinking if I do overcome my reservations about AC power, and got an inverter to use that, it would really open up the playing field as to my options as I would be able to find things to use that power productively more easily as it can be challenging once you get to higher power devices since of course the preference is for AC at a certain point due wire thickness limitations of DC. So perhaps is makes sense to get over that hurdle.

Is AC considerably more dangerous than DC? and if so what are the extra safety precautions one must take when building it into the system? I am just looking it up again and while there is some disagreement it is generally understood that AC is more dangerous. More dangerous is relative though I guess but I had shied away from it from a better safe than sorry perspective and not having any particular pressing need for AC, as most of my stuff I use is low power and wanted to keep it that way until now.

[pierremontagne]

Another thought is I have terrible rodent issues, namely voles and mice and they sometimes crawl on my van which sucks.

Maybe an electric perimeter would be a good deterrent? though they burrow underground too so I don't know if that would work since the ground would not be able to be electrified too would it? Maybe some metal sheet down a certain way then the electric fencing.

[brucehoult]

The thing you suggested seems like an all in one thing like a Jackery but seems like it would be a waste for me since I already have all the other equipment, just a case of converting the DC to AC, if indeed I need to.

We have no idea what equipment you already have.

You only mentioned a 100Ah battery, which is meaningless without the voltage. It could be 0.5kWh (6V) or 1kWh (12V) or 3kWh (48V) or other variations.

Certainly with a suitable battery you only need to add an inverter.

I don't know why you are so afraid of AC power if the hot circuitry is all inside a proper enclosure and uses standard plugs and sockets made for the appropriate environment (indoors or outdoors) and with an RCD if in a wet area. Literally billions of people have 120V or 240V AC in their homes and most of them don't die.

[pierremontagne]

The thing you suggested seems like an all in one thing like a Jackery but seems like it would be a waste for me since I already have all the other equipment, just a case of converting the DC to AC, if indeed I need to.

We have no idea what equipment you already have.

You only mentioned a 100Ah battery, which is meaningless without the voltage. It could be 0.5kWh (6V) or 1kWh (12V) or 3kWh (48V) or other variations.

Yes I forgot to mention; it is 12VDC.

Certainly with a suitable battery you only need to add an inverter.

Ok, but as I added more thoughts over on my new thread, if I want to make it separate for the AC outdoors this probably won't apply.

I don't know why you are so afraid of AC power if the hot circuitry is all inside a proper enclosure and uses standard plugs and sockets made for the appropriate environment (indoors or outdoors) and with an RCD if in a wet area. Literally billions of people have 120V or 240V AC in their homes and most of them don't die.

That is what I was getting at really, if it is any more dangerous than common household setups. Either the installation part or after setup in terms of risk of electrocution. It is not a 1:1 comparison because most householders don't do their own electrics so I am asking about the risks of installation process and then after safeguards to keep in mind, if any, once I have AC in the system, both of which would be handled by someone else in the case of household electrics.

[Seekonk]

I have 3KW of panels going into a 500W charge controller.  Why do you think you need to disconnect them in the summer. Don't you have rain or clouds that limit power on some days.  I'd find something to o with that excess power in the summer.   I have a camp and make hot water with the extra energy, got rid of my propane heater.

[floobydust]

Is there any meaningful damage to them being unplugged yet left out in the sun?  [...]

Didn't we already realize that solar panels run hotter when they have no load? Yes it's controversial, counter-intuitive until you look at the physics.
https://www.eevblog.com/forum/renewable-energy/quick-one-unused-solar-panel-on-the-roof-better-short-or-open-circuit

[pierremontagne]

I have 3KW of panels going into a 500W charge controller.  Why do you think you need to disconnect them in the summer. Don't you have rain or clouds that limit power on some days.  I'd find something to o with that excess power in the summer.   I have a camp and make hot water with the extra energy, got rid of my propane heater.

I already discussed why earlier, that I have to physically go under the van to connect and disconnect the Anderson connector any time I want to drive the van so it is more convenient not to have it plugging in if it isn't used.

Just as a minor update, I have had them unplugged for a couple of days now and it seems I am in a bit of deficit, down to 13.1 on lifepod which would indicate 40% approx charge with only the 300W. So seems they aren't totally unneeded just yet.

Is there any meaningful damage to them being unplugged yet left out in the sun?  [...]

Didn't we already realize that solar panels run hotter when they have no load? Yes it's controversial, counter-intuitive until you look at the physics.
https://www.eevblog.com/forum/renewable-energy/quick-one-unused-solar-panel-on-the-roof-better-short-or-open-circuit

We who? I don't know I was present during this conversation? lol. Hotter yes, but by how much? from what I read it is an insignificant increase of a few degrees. Also, I read a very good point yesterday when doing more reading around on the subject and that was that when your battery is full and the MPPT effectively shuts down then this is just the same as having them disconnected anyway. When they are connected lately I noticed that the battery would register as full after only an hour or two of sunlight so in fact it is pretty much the same as having them disconnected most of the day anyway!

[Seekonk]

I have 3KW of panels and a 500W charge controller.  No problem with the excess.  I do bring in 500W of panels in the winter because they sit under trees and dropping branches will damage them.  I do a lot of direct power from the array. Example, I run a LG clothes washer directly from array voltage with no battery.

[nfmax]

You could rent out the panels to someone who needs them during the summer…

[pierremontagne]

I have 3KW of panels and a 500W charge controller.  No problem with the excess.  I do bring in 500W of panels in the winter because they sit under trees and dropping branches will damage them.  I do a lot of direct power from the array. Example, I run a LG clothes washer directly from array voltage with no battery.

I think you misunderstood the question. I am not worried about overloading the MPPT. I know it works fine. I want to know instead how to make use of the excess power that is generated. Lol clothes washer would be a luxury item for me I have no need for.

[Seekonk]

I seldom understand what anyone is talking about in solar.  I run a large capacity LG washing machine (and most of the house) on just four panels totaling 900W.  No battery is needed.  I just feed the HV DC into the high voltage section of an old MSW inverter.  A direct drive washer only takes about 400W.  In this same system I also have a water heater just for the laundry.  Hot water is piped to cold inlet so all cycles use hot water.  Clothes come out steaming and there is no trace of mold which is often seen in these front loaders.  There is no need to live like a refugee.  My wife said she wanted a dishwasher.  Evidently telling her I thought I married one was the wrong answer.  Even dishwashers are easy.  They draw less than 100W and use about 100WH if the heater is eliminated.   I ran the heating element from the panel DC.  No need to disconnect panels.  All this stuff can operate with panels connected to charge controller.  All domestic hot water is free from PV. I don't have many pictures with me, but these are the panels on my garage facing east.  They supply 70% of the power the house uses each day.  This is not a technology problem, it is an education problem.  Solar people are just drawn to watching idiots on YT and they wonder why nothing works well.