TrailManor Owner's Forum - View Single Post

RockyMtnRay · 07-26-2003, 09:33 AM

Bill...

I did this sorta scientifically by using the handy-dandy worksheet that RV Solar has on their website (http://www.rvsolarelectric.com/custom.htm). I camp solo about half the time, the rest with one companion...but in my case that's not the major determinants of electrical usage. My electric usage comes mostly in the following categories:

--As noted before, I mostly camp at high altitude where nighttime temperatures are often in the 30s even in mid-summer. And I'm usually up well before dawn and often run the furnace for an hour or more in the mornings, sometimes for half an hour in the evenings. Figured I'd need about 15 amp-hours just for the furnace.

--Assumed I'd probably use other electrical devices (in particular the water pump) to the tune of around 4 amp-hours each day.

--I like a LOT of light...especially when I'm trying to wake up and get going in the morning. If I have my druthers (and the juice to do it), I'll simultaneously turn on most of the TM's overhead lights...and both of the "elegant" lights. Figured I'd need around 15 amp-hours for 2 to 3 hours of lighting.

--As a self-employed software developer with never-ending deadlines and client tech support requirements, the only way I can get away (even for 2-day camping trips) is to bring my laptop along. Every day I have email, a check on my servers (I run several database servers out of my home office), some development work, etc. Since I use my cellphone as a wireless modem at 14.4K (max), file & email uploads/downloads, web browsing, etc. take quite a bit of time. All in all, I figured about 2 to 3 hours or roughly 16 to 24 amp-hours to power the computer each day.

--Miscellaneous...like recharging my digital camera, cellphone, etc....about 4 amp-hours.

Add it all up and my daily power use (if I have all that I can get) is around 70 amp-hours. Add in a fudge-factor for battery and line-loss and it comes up closer to 80 amp-hours.

Based on the assumption that I'll have good sunlight for about 6-8 hours a day (some days more, some less because of afternoon clouds), I calculated that I'd need a panel array that could generate about 10 amps. Based on RV Solar's offerings and pricing, that turned out to be their Jumbo 120 watt Kit (7 amps of generation) plus a second 50 watt panel (3 amps of generation). Their Kyocera 50 watt secondary panel was only $20 more than a 40 watt panel; but the 80 watt was $100 more than the 50 watt. It seemed that for my needs the sweet spot in terms of watts/dollar system cost (including controller, wring, mounts, etc.) was at 170 watts total.

I'm guessing the total weight of roof mounted components will be somewhere around 50 lbs. This is partly from bits and pieces of info I've picked up elsewhere and partly from the shipping weight of my order (60 lbs) The RV solar price list shows 12 lbs each for their kits but I think that's probably way too low.

I personally am kinda doubtful that a 50 watt panel would be enough to recharge your battery every day unless you're extremely frugal with power usage...and have cloud-free skies and a shade-free location for your panel nearly every day. A 50 watt panel is only going to generate around 3 amps in full sunlight under normal temperature conditions.

07-26-2003, 09:33 AM	#4
RockyMtnRay TrailManor Master Join Date: Jul 2001 Location: Colorado Springs, CO Posts: 816	Re:Adding Solar Panels Bill... I did this sorta scientifically by using the handy-dandy worksheet that RV Solar has on their website (http://www.rvsolarelectric.com/custom.htm). I camp solo about half the time, the rest with one companion...but in my case that's not the major determinants of electrical usage. My electric usage comes mostly in the following categories: --As noted before, I mostly camp at high altitude where nighttime temperatures are often in the 30s even in mid-summer. And I'm usually up well before dawn and often run the furnace for an hour or more in the mornings, sometimes for half an hour in the evenings. Figured I'd need about 15 amp-hours just for the furnace. --Assumed I'd probably use other electrical devices (in particular the water pump) to the tune of around 4 amp-hours each day. --I like a LOT of light...especially when I'm trying to wake up and get going in the morning. If I have my druthers (and the juice to do it), I'll simultaneously turn on most of the TM's overhead lights...and both of the "elegant" lights. Figured I'd need around 15 amp-hours for 2 to 3 hours of lighting. --As a self-employed software developer with never-ending deadlines and client tech support requirements, the only way I can get away (even for 2-day camping trips) is to bring my laptop along. Every day I have email, a check on my servers (I run several database servers out of my home office), some development work, etc. Since I use my cellphone as a wireless modem at 14.4K (max), file & email uploads/downloads, web browsing, etc. take quite a bit of time. All in all, I figured about 2 to 3 hours or roughly 16 to 24 amp-hours to power the computer each day. --Miscellaneous...like recharging my digital camera, cellphone, etc....about 4 amp-hours. Add it all up and my daily power use (if I have all that I can get) is around 70 amp-hours. Add in a fudge-factor for battery and line-loss and it comes up closer to 80 amp-hours. Based on the assumption that I'll have good sunlight for about 6-8 hours a day (some days more, some less because of afternoon clouds), I calculated that I'd need a panel array that could generate about 10 amps. Based on RV Solar's offerings and pricing, that turned out to be their Jumbo 120 watt Kit (7 amps of generation) plus a second 50 watt panel (3 amps of generation). Their Kyocera 50 watt secondary panel was only $20 more than a 40 watt panel; but the 80 watt was $100 more than the 50 watt. It seemed that for my needs the sweet spot in terms of watts/dollar system cost (including controller, wring, mounts, etc.) was at 170 watts total. I'm guessing the total weight of roof mounted components will be somewhere around 50 lbs. This is partly from bits and pieces of info I've picked up elsewhere and partly from the shipping weight of my order (60 lbs) The RV solar price list shows 12 lbs each for their kits but I think that's probably way too low. I personally am kinda doubtful that a 50 watt panel would be enough to recharge your battery every day unless you're extremely frugal with power usage...and have cloud-free skies and a shade-free location for your panel nearly every day. A 50 watt panel is only going to generate around 3 amps in full sunlight under normal temperature conditions.