We are getting solar panels on our roof within the next month and I was wanting to separate out some of our outdoor devices from the house, the pool being one of those. Does anyone have any experience is doing an off grid system for pools where they could give advice or even materials that will help with the process? With doing HVAC and industrial equipment I know how to size most things and read the the nec to adhere to any code requirements. I am also extremely comfortable doing electrical work up to 600v as I've done a lot of that. Any help would be awesome!!
Solar panels to run pump and swg
- Thread starter digidoggie18
- Start date
Why do you want your pool (or other things) off grid, if the rest of your house remains grid-tied?
i have solar panels, a 13.5kw system and i did not remove anything the system powers the whole house including the pool pump, heater etc.
Just an effort to reduce usage because the house will still be on the grid. We are shooting for 0 electrical bills and reducing my usage will aid in that by offsetting my day usages. Unfortunately all we are allowed to do is net usage here. We've been talking with about 5 companies in the area and that's all that is offered here
They have us doing an 8.96kw system but knowing our usage, it wouldn't be enough I feel as it was an average. As far as more panels were only have an additional 4 we could put on the roof as we are already at 28 so expansion is limited as we want to keep big panels off the ground till we get the shop up on the side of the house with the pool. Once that happens we will consider moving up to the roof of the shop.
I looked it up. In Pueblo County the energy supplier buys excess electricity at $0.045/kWh. However this is only excess. Real time if your solar panels are producing electricity, and your are using that electricity, then you pay nothing. For example if it’s full sun at noon and your panels are putting out 8 kW, then you have three situations:
- Your draw is less that 8 kW, for example you are drawing 5. This means you’re making 3 kW more that you use, and the electric supplier would pay you for that 3. For every hour like this, you’d get paid $0.135
- Your electricity demand is 8 kW. Here you’d be getting free power, not paying anything nor getting paid.
- You’d demand is more than 8, for example you are drawing 12 kW. Here you’d pay for 4 kW as normal at whatever price you normally pay, the remaining amount is free.
Ultimately you will be better off to leave ALL solar panels connected to the grid, along with all your pool equipment. This will bring maximum savings with the convenience of having the grid as a backup for cloudy days or times you need to run when the sun isn’t out.
The way you save the most money with your future solar array is to time the electric loads in your house, not split your array. Your goal is to run any electric loads that can be run at different times of the day to run when the array is producing power. For example, set your pump timer to filter during the day. Run your dishwasher or electric clothes dryer during the day instead of during the night. Etc.
Does this make sense? I can make examples with numbers if that would be useful.
- Jul 3, 2013
- 9,027
- Pool Size
- 15000
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool SJ-40
For off grid it will have to have batteries with it.. If you made to much power that power has to go somewhere...
Say your pump and everything off grid is using 2kw... it is sunny out and your panels are making 4 kw... that extra 2kw has to go somewhere and you do not want it going into your pump... with the batteries it is able to push it into them and charge them.
Say your pump and everything off grid is using 2kw... it is sunny out and your panels are making 4 kw... that extra 2kw has to go somewhere and you do not want it going into your pump... with the batteries it is able to push it into them and charge them.
We will be using excess. They never allow you to break even here but only average your usage for the panels.. last month we used 1931KWh although I am not sure what that equates to with KW in terms of our system. That is all unfamiliar to me yet. In the cold season we will use a lot less than during the summer though. Summer I believe we will be over and have to buy electricity. Regardless Energy companies are going to try to not allow you to get off scott free on energy consumption no matter what we think. If they did, they would be out of business. Our plan was to possibly get a payout on credits and push that back into our loan on the system to drive that cost down as quick as we can. Regardless, we expect electrical needs to go up as Colorado starts phasing out natural gas which sucks for us massively as Electric and heat pump heat leave the home feeling too cold resulting in higher usage (I am a licensed Hvac Contractor) and the electric for electric back up I have always hated due to the high energy use and smells associated with it. Then we also have no room for a normal water heater so we have an on demand gas water heater. Once they phase out, we are only left with electric options which will skyrocket use. Removing the pool system from our home would free up a lot of that load due to the system running constantly (intex equipment isn't very power friendly) with that being said, the goal is to do away with intex and do a different SWG and a much more efficient pump with variable stages for pumping as well as possibly an ECM pump as I've worked with ECM blowers extensively. although I am still researching options. Most likely we will be looking for a DC pump as this is the future in terms of efficiency. I have also been looking into panels from china for this as they have some of the cheapest but best quality panels out there. Monocrystalline to be exact.
That was the plan as well as intelligent charging which most "kits" come with. I have been slowly looking into options for that and seeing what is good and bad out there. We were also wanting storage to be able to run at night as the Night panels still aren't available yet on a wide scale ( read an article about the introduction of panels that pull energy at night)
Your 9 kW panel array at a 40° tilt facing south will produce an average of 6.83 kWh/day in June, or 200 kWh/month. Honestly, I cannot see any way breaking off panels to dedicate to pool will be better off than using the entire array for your house. Your array is TINY compared to your usage, 10% of your monthly usage at the peak of summer. I really think your best bet is to put it all to your house to reduce your usage as much as possible.
I took a solar energy course in college recently, I can help you with really detailed numbers if you'd like and are willing to share more details of your specifics.
That number seems very low for a 9kw system. Similar latitude here with a smaller system and made 1400kwh last month.
I agree but... That's with all the quotes we've been getting... Maybe we shouldn't do this and I should just find a way to do it myself and have someone hook it up.. I've found that most of the solar contractors out here suck horribly and are very pushyThat number seems very low for a 9kw system. Similar latitude here with a smaller system and made 1400kwh last month.
Stuff like this has me left wondering who to truly believe.. I dunno, maybe it's just best to stick to leaving panels entirely out of the question for our whole house.. they really seem like more advertising vs feasibilityThat number seems very low for a 9kw system. Similar latitude here with a smaller system and made 1400kwh last month.
- Jul 3, 2013
- 9,027
- Pool Size
- 15000
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool SJ-40
Grid Tie Solar System Kits for Sale Archives
This is a nice one
unboundsolar.com
This is a nice one
13.5 kW Grid-Tied Solar System with Enphase IQ7A Microinverters and 30x Astronergy Solar 450w Panels
UNBOUND Enphase IQ7A Inverter Gridtie System for 30 Astronergy 72 Cell Modules
unboundsolar.com
Solar can be intimidating. There are many factors to consider to make sure that it makes fiscal sense.
One thing you mentioned was trying to have no electric bill. This is usually not the most cost effective goal.
I would suggest researching how your power company handles billing of net metering, as it can have a huge impact on your plans.
Yeah, you are totally right. I was doing it too quick and quoted the kWh/m^2/day value, which is NOT kWh/day!That number seems very low for a 9kw system. Similar latitude here with a smaller system and made 1400kwh last month.
A 9 kW system at the OP's location, with a 45° tilt (I don't know if the OP is getting panels mounted flat on an existing tilted roof or tiltable mount panels), is 1287 kWh/month in June:
At lat = tilt angle (38°), which yields highest yearly average power, you get:
You can further tilt the panels to get more power in summer (and less in the winter), or if you have adjustable panels you can change it seasonally...solar is fun. Lots of options!
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Also note the above site (which is amazing for planning solar installations) calculates based on average weather at the particular location, in addition to the sun hours at that location. So a clear weather month an array will make more than listed on that site, and a cloudy month it would make less.
Let me see if I can explain why you don't want to have part of your array not part of your grid-tied array more simply.
First off, load is load. If your pool pump takes 3 kWh/day to run, it will take that regardless of if it's directly tied to solar panels or if it's tied to the grid. So you need to provide it with 3 kWh/day either by the grid or solar panels. Necessarily, to run something completely by solar, you need to oversize the solar array, because unless they are on really expensive tracking mounts, their peak output is at solar noon, so to run some load for x amount of hours per day they will always need to be sized bigger. So without batteries, anything your load doesn't use is wasted. That's how PV panels work. Use it immediately or lose it. So now your solar panels for the pump are making more power per day than the pump uses, simply because this is how it must be done. So we have a couple different solutions to avoid this wasted power.
First, we could have a pump that varies speed based on the available power. This works, but after you get enough flow more isn't useful. See all the discussion on variable speed pumps here on TFP. Basically what I see happening with this is you aren't wasting the electrical power by not getting it from the panel when it's available, but you're still going to waste it by running the pump faster than needed.
So secondly let's look at batteries. Batteries solve the wasted power issue by allowing you to charge the batteries in peak power and then use the batteries when the power is not at peak. However, batteries are expensive and will require the purchase of a battery management system too. There is also efficiency loss in both charging and discharging batteries.
Thirdly we have grid tied. Here, there are no batteries. The solar panels are grid tied, so assuming you have a MPPT grid-tied inverter, 100% of the available electricity the panels can produce will always be drawn from the panels, because the grid will take any and all power you don't use. Now, if the sun is shining, and your pump is running, the power from the panels goes directly into your pump, just as if you had panels directly connected to the pump! The key difference, however, is that if the panels produce more power at any point than the pump is using, it gets sent to the grid and you get some sort of credit. It doesn't matter what this credit is, just that if you have any excess power you get some sort of credit for it.
In no case will a 9 kW array eliminate your 1900 kWh/month electric bill, since you will only get 1200-1300 kWh/month from the array as I posted earlier. So it will only ever reduce it. Please have everything tied together to get the most possible electric bill reduction. On top of that having it tied together won't limit when you can run your pump. Need to SLAM for some reason? No worries, the grid will supply your power! Cloudy for two weeks on end? No worries, your pool is still circulating and filtering.
Now, if you do ultimately tie everything together, as I suggest, to get the most reduction on your electric bill you will still need to time your electric consumption. Maximum bill reduction will be when your overall power consumption uses the most power from the panels, not the grid, because a credit for 1 kWh won't buy 1 kWh back from the grid. So certainly, get rid of the power hogging Intex pump. Get an efficient variable speed pump, run only as fast and for as long as needed to skim/circulate/filter, and time it to run during peak sun hours. Use your dishwasher delay to wash dishes in the middle of the day instead of the middle of the night. If you still aren't using all your power from your panels try to dry clothes (if you have an electric dryer) in the middle of the day instead of evening or night. Etc etc.
Further, less relevant example of why everything should be tied together (I'm totally rambling now, if I haven't been already): Tying more things together ultimately leads to a more reliable system overall. This is why national electric grids exist. If one power plant drops out, no worries. All the customers will get power from the grid, and the rest of the power plants on the grid will output slightly more power to compensate. The bigger the grid, the better things are. Lower cost sources can be used when demand is low even if they are states away, only bringing higher cost sources online when demand needs them. This leads to lower power costs for everyone. Oh yeah, and remember how tons of people lost power in Texas last winter? This is because most of Texas is on one grid that is NOT tied to either the east or west national grids, which all the rest of the states are either on one grid or the other. Texas lost like half their generating capacity, so they had to cut like half their customers or the entire grid would go out. But, if Texas had been tied to, say, the eastern national grid? No worries that half the plants in Texas went out. All the northern states had power plants that weren't affected by the cold weather. Texas would have been powered by all the power plants in other states. While some customers certainly would have lost power due to local downed lines and such, the main issue of Texas loosing half their generating capacity wouldn't have mattered, the rest of the grid would have taken up the slack and many Texans would have faired much better.
Anyway, I'm off my soapbox now. If you have questions, or would like specific examples, let me know. Otherwise I'll be quiet now.
First off, load is load. If your pool pump takes 3 kWh/day to run, it will take that regardless of if it's directly tied to solar panels or if it's tied to the grid. So you need to provide it with 3 kWh/day either by the grid or solar panels. Necessarily, to run something completely by solar, you need to oversize the solar array, because unless they are on really expensive tracking mounts, their peak output is at solar noon, so to run some load for x amount of hours per day they will always need to be sized bigger. So without batteries, anything your load doesn't use is wasted. That's how PV panels work. Use it immediately or lose it. So now your solar panels for the pump are making more power per day than the pump uses, simply because this is how it must be done. So we have a couple different solutions to avoid this wasted power.
First, we could have a pump that varies speed based on the available power. This works, but after you get enough flow more isn't useful. See all the discussion on variable speed pumps here on TFP. Basically what I see happening with this is you aren't wasting the electrical power by not getting it from the panel when it's available, but you're still going to waste it by running the pump faster than needed.
So secondly let's look at batteries. Batteries solve the wasted power issue by allowing you to charge the batteries in peak power and then use the batteries when the power is not at peak. However, batteries are expensive and will require the purchase of a battery management system too. There is also efficiency loss in both charging and discharging batteries.
Thirdly we have grid tied. Here, there are no batteries. The solar panels are grid tied, so assuming you have a MPPT grid-tied inverter, 100% of the available electricity the panels can produce will always be drawn from the panels, because the grid will take any and all power you don't use. Now, if the sun is shining, and your pump is running, the power from the panels goes directly into your pump, just as if you had panels directly connected to the pump! The key difference, however, is that if the panels produce more power at any point than the pump is using, it gets sent to the grid and you get some sort of credit. It doesn't matter what this credit is, just that if you have any excess power you get some sort of credit for it.
See above. For a simplified example considering fixed loads, if your pump draws 1 kW, and your house draws 12 kW, you have these situations:
- 1 kW of PV dedicated to the pump, 8 kW of PV dedicated to your house. Your grid load is 12 - 8 = 4 kW. You pay for 4 kW of power.
- 0 kW of PV dedicated to the pump, 9 kW of PV dedicated to your house. Your house load is now 12 + 1 = 13 kW. Your grid load is 12 - 9 = 4 kW.
In no case will a 9 kW array eliminate your 1900 kWh/month electric bill, since you will only get 1200-1300 kWh/month from the array as I posted earlier. So it will only ever reduce it. Please have everything tied together to get the most possible electric bill reduction.
On top of that having it tied together won't limit when you can run your pump. Need to SLAM for some reason? No worries, the grid will supply your power! Cloudy for two weeks on end? No worries, your pool is still circulating and filtering.Now, if you do ultimately tie everything together, as I suggest, to get the most reduction on your electric bill you will still need to time your electric consumption. Maximum bill reduction will be when your overall power consumption uses the most power from the panels, not the grid, because a credit for 1 kWh won't buy 1 kWh back from the grid. So certainly, get rid of the power hogging Intex pump. Get an efficient variable speed pump, run only as fast and for as long as needed to skim/circulate/filter, and time it to run during peak sun hours. Use your dishwasher delay to wash dishes in the middle of the day instead of the middle of the night. If you still aren't using all your power from your panels try to dry clothes (if you have an electric dryer) in the middle of the day instead of evening or night. Etc etc.
Further, less relevant example of why everything should be tied together (I'm totally rambling now, if I haven't been already): Tying more things together ultimately leads to a more reliable system overall. This is why national electric grids exist. If one power plant drops out, no worries. All the customers will get power from the grid, and the rest of the power plants on the grid will output slightly more power to compensate. The bigger the grid, the better things are. Lower cost sources can be used when demand is low even if they are states away, only bringing higher cost sources online when demand needs them. This leads to lower power costs for everyone. Oh yeah, and remember how tons of people lost power in Texas last winter? This is because most of Texas is on one grid that is NOT tied to either the east or west national grids, which all the rest of the states are either on one grid or the other. Texas lost like half their generating capacity, so they had to cut like half their customers or the entire grid would go out. But, if Texas had been tied to, say, the eastern national grid? No worries that half the plants in Texas went out. All the northern states had power plants that weren't affected by the cold weather. Texas would have been powered by all the power plants in other states. While some customers certainly would have lost power due to local downed lines and such, the main issue of Texas loosing half their generating capacity wouldn't have mattered, the rest of the grid would have taken up the slack and many Texans would have faired much better.
Anyway, I'm off my soapbox now. If you have questions, or would like specific examples, let me know. Otherwise I'll be quiet now.