800w Solar Project

Most people install solar panels just to put a load on them. What is the use of it when not?

You can count the elements - squares of 156mm X 156mm, and when you have 36 wafers, your panels will only give max. 21 Volts DC in heavy sunlight.

With a load on them they drop quickly.

If you want no load on the panels, interrupt between DC of panels and input of inverter(s). I had 250 Watts inverters running on 5000 watts of panels.

Here I was good for 28 volts per inverter.

Most inverters do not take more than they are designed for. The rest translates in a slightly higher Output voltage of your panels (your 50 watts over size will probably cause the voltage to go up with 0.5 to 0.7 volts)

Do not let your sleep about that 50 watts. It is like the speaker myth. Amp lower in wattage? Forget it.

In the mean time I have some 40 Kilowatts up and running. In professional and experimental stages.

When you want to play sure, sure, use the excess to load extra batteries and protect your batteries accordingly with a voltage switch.

Ive worked with these folks on a couple of pv systems. Excellent knowlegeable service with the design portion and their prices are reasonable if you choose to purchase from them.

www.backwoodssolar.com

hydrogenhead-

Are you sure you want to use solar panels? If you decide too, you are taking the risk of destroying the shed, the panels, all electrical controls, all the shed contents, any items adjacent to the shed and finally possibly cause injury or death to personnel. Solar panels have lost some of their appeal. When the structure catches on fire, unless it is a small one, there is no way to put the fire out except roasting marshmallows and hot dogs on the flames. Not only do the mounting brackets make it impossible for firefighters to go up to the roof to cut vent holes but the voltages of these units could kill if contact is made with some of the wiring. Even with shut off switches the voltage is still being generated. The only way to handle this is to go to each individual panel and electrically disconnect it from the bus lines. Common fire fighting method for this type of structure is to let it burn to the ground.

This recently happened at a Dietz & Watson 3-400,000 sq. ft. meat processing plant in Delanco, NJ. A small fire started inside, progressed up to the ceiling and broke through the roof. Once it got to the roof the building was going to be a total loss because of the solar panels. This fire was at least a 7 alarm one with mutual aid brought in from all over the county and adjacent counties.

One of the worst things about this fire was the stench after the major portion of the fire was finally extinguished. All that meat was burnt or partially bunt and caused a smell that forced local homeowners to evacuate for several days!

Look into this before committing to it. Check with the local fire Marshall and ask him about his experiences with them.

Good Luck, Old Salt

20 volts isn't going to kill anyone. I'm more worried about the probability of burning chainsaws falling out a storm cloud than a 20v solar array on a shed spontaneously combusting.

hydrogenhead-

I'm sorry that a well intended and very valid answer was perhaps disregarded and perhaps satirically replied to. Don't worry, I'm not offended. My purpose was to take a rather ambiguous question and try to give an intelligent answer to it.

My comments about the voltage were addressed to the most common manner of wiring panels on fixed structures, such as a shed is. It is the preferred manner to wire panels in series for this. Voltages in excess of several hundred volts can be present when wired in this manner. Wiring is done in series to reduce the amount and size of wiring, increase the voltage and decrease the current in order to use inverters more efficiently (they handle higher voltage better than current, P= V*I). Had you stated that the panels were to be connected in parallel at 20 volts, a less efficient manner, I would not have mentioned this. Good Questions --->Good Answers, Ambiguous Questions ---> Ambiguous Answers.

If the structure should catch on fire, either from an internal source or an external source it will still burn. Internal sources include but are not limited to the inverters, a stored hot engine, electrical short circuit, careless smoking. static spark when transferring flammable fuels, etc. External sources include fires in adjacent items/structures causing radiate, conductive or convection heat, brands from other fires, recreational or other source fires, transfer of flammable fuels, or many other potential sources. In any of these potential scenarios you will not have to worry about flying burning chain saws, no firefighter would ever go up on the roof to try to extinguish the fire, vent the roof with a chainsaw or any other roof or aerial tactics. The panels and the framing for them would still be there and too dangerous for anyone to be up there. Also don't stand close enough to the structure that you could get hit by a chain saw, even though one will not be in use, you would be a nuisance to the firefighters and they would firmly tell you to leave. If that doesn't work they call upon the police to help them clear the area. The only alternative would be to get some marshmallows or hot dogs and hope the radiant heat was enough to cook them.

Although the shed would probably not spontaneously combust, as you have inferred, it doesn't need to. There are plenty of other ways for it to catch fire. One thing is a constant though, when it catches fire its only a short time till it is beyond saving. It will be gone well before it finally gets to the point in time when "the wet stuff can be put on the red stuff"!

Please don't invest money wastefully in an elaborate system. Any type of fire beyond a match or candle will be the ruin of a good idea.

Also of mention is that an adjacent community to me had an identical situation with a small ranch house last month. We arrived as a mutual aid fire company and were kept away from the structure because of the dangers from the panels on the roof. The homeowner was shouting, cursing at us and begged the police to have us arrested for not aggressively attacking the fire. Cop told him to be get back and be quiet (not the exact wording) or he would have a temporary residence in a 6'x10' room. We eventually put some water on the adjacent residences to save them from brands and radiant heat. A firefighters 1st priority is firefighter life safety (don't get killed), 2nd the life safety of the civilian personnel and 3rd the loss of property.

Go ahead and do what you want, its your money and system. If it catches fire please don't call the fire dept., they won't be of any help to you with your arrangement of panels. Also I hope you are not in a town adjacent to mine. I don't like to be seen standing around at a fire scene!

Good Luck, Old Salt

We're still waiting on the intelligent answer.

I would suggest buying a big rig truck battery and charge it when the bike isn't hooked up to the solar panels, then you could charge the bike at night off the battery.

He might be doing that. Check posts hydrogenhead.

129CBRider-

I usually don't reply to questions with a tone of sarcastic or irrelevance but here goes:

Questions expounded by CR4 members with their craniums, especially the Pinna, tympanic membrane, cornea, and septum immersed in silicon dioxide, SiO₂, tend to also suffer from cerebrum minimus. This condition frequently lends itself to confusion and debilitory functions in communications, especially of a technical manner. They also have a predisposition for avoidance of accepting opinions and knowledge of other persons. This is similar to the reflexes exhibited by Neanderthal Man.

If you are "still waiting on the intelligent answer" this is analogous to waiting for a bus. The bus has already left so the person waiting for it appears to be very foolish.

As for a big rig battery and a bike, it will take additional circuitry in order to keep that apparatus from simulating C-5.

If you do not understand the problems of solar panels on roofs during fires, perhaps seeing video of the 11 alarm fire at the Dietz and Watson Warehouse fire in Delanco, NJ, 2 months ago perhaps the following videos might make a more realistic impression on you--

Massive fire at Dietz & Watson warehouse in Delanco, New Jersey http://www.youtube.com/watch?v=cKwOuYyXkrI

Delanco 11 Alarm Fire Video, Radio Audio & Photos Part 1 http://www.youtube.com/watch?v=0w4rg_wJEuw

Delanco 11 Alarm Fire Video, Radio Audio & Photos Part 2 http://www.youtube.com/watch?v=WwVu-Lgt7Es

Good Luck, Old Salt

That was a long and intelligent answer.

I do plan on storing the solar power in the battery and then charging my bike from that whenever I like. I will also be getting two Trojan T105 batteries for extra capacity. They will not be linked in parallel with my existing battery, but I will have a Raspberry Pi computer connected to the internet controlling relays which I can log into in order to switch battery banks or turn on a grid tie inverter.

Internet controlling relays. Do you have any link to these? It is perhaps what I am still looking for. Thank you. D

Sorry, I phrased it wrong. There is a library for the Raspberry Pi called webiopi. It sets up a server and webpage where you can click on the the GPIO outputs to turn them on and off. You would need a mosfet or something to control the 12v switching coil on the relay. You can password protect it I think but if someone hacked it they couldn't do any damage.

Ace hardware has Wifi HVAC thermostats that are basically just switches for relays.

Just don't buy a pressure cooker at the same time or they'll vaporize you at the cash register. :)-

As far as I know, (insteon, smart home sells these too), the settings on which to switch are WIFI controllable. I need to get a read signal (from XML file) and make this do the switch over WIFI. Thank you. D

asking a little more for safety then:

What are the intended separators between the collectors and shed?

With 1980 solar still not burning the houses down , common-then 1.1/2" poly-iso has worked well under the painted galv-alumn deck of the collectors and skirt edges, flashed only top and sides (1 kw each panel )

The optimum temp of most PV arrays is 25C ...(77F) ... so airflow between the PV array and the roof is recommended. Some even enclose the sides and use a fan or natural hot air rising to get some cooling airflow across the array underneath. I never have worked out if some of the generated electricity to drive a fan for enhanced airflow is a net gain.

It is just a way to break the sandwich loose. The wafers are "stuck" on the glass from the bottom. See how this creates tensions in the glass (bulgin)

JP76-

Unfortunately, at this time there is no proven and approved isolation/insolation available for solar panel mounting onto roofs. At the present time it is air. Frames of some appropriate configuration are secured to the roof, with appropriate flashing, and the frame of the cell mounted to these. Sometimes for small installations, the framing consists of unistrut/kindorf channel and fittings.

The close proximity to the roof and the live electrical wires/controls are what make fire fighting most difficult. Also getting water between the panels and the roof are also problems confronted with. These are what prevented firefighters from getting an early start on the Dietz and Watson facility.

Sorry there is not a clear answer for you on this one. As the use of solar panels progresses the standards making groups will have to develop a standard.

Good Luck, Old Salt