Customer question (received via email 10th May 2020):
Hi. Looking for a small solar panel to maintain a charge on a 110Ah rib battery. Need to mount on the stern A frame as boat will have cover on it when not in use, may need 6m of cable or so. The panel will be out in the elements all year. Smallest would be best and I'm guessing I may have to make some sort of backing/mounting plate. Could you let me know what my best options are please.
Willgen Reply (Email from Bill 11th May 2020):
Many thanks for getting in touch.
To maintain a 110Ah battery throughout the year (ie through winter as well as rest of year) you need approximately 10W of solar output. Assuming that the panel will be mounted flat (horizontal) on the A frame of the rib this will reduce winter output considerably due to the low height of the sun in the sky so you need to go for 20W minimum to account for this. This will protect against natural battery drain only - if you have additional loads on the battery when the boast is at rest these will need to be taken into account and a larger panel may be required.
There are numerous options but I would narrow it down to an Optimate Solar charger or DIY kit based around an Ameresco glass fronted solar panel or PV Logic semiflexible panel.
Optimate Solar Charger
For ease of installation I would recommend the Optimate 20 solar charger £139.95. The Optimate charger comes with a fused lead with ring terminals for permanent connection to the battery and a charge controller that will manage battery charging and prevent battery damage from over charging. Once battery connections have been done it is simple "plug and play" installation. The solar panel comes with a hole at each corner that can be used for mounting. A 4.6m extension cable is available to extend the 2m cable that comes attached to the solar panel. I can supply a rubber boot that provides extra protection to the plug connector between solar panel cable and extension cable if that will be exposed to the elements. The solar panel is fully weatherproof and can be permanently installed outside. The charge controller is splash proof but needs to be mounted in a position close to the battery protected from the elements.
Other options would be to use a standard glass fronted or semi-flexible solar panel and charge controller. You would need cable and battery connections as well. If going down this route you could either go for a single 20W panel or for two 10W panels mounted either side of the A frame connected in parallel back to a single charge controller.
Ameresco are the best glass fronted, aluminium framed marine panels around or you could go for a PV Logic semiflexible panel. Both come with approx. 4m cable "potted" into the back of the panel. The kit you would need would be as follows (prices correct May 2020):
- 2 x 10W solar panels Ameresco glass £67.95 each or 2 x 10W PV Logic Flexi panels £69.95 each - or single 20W panel if you prefer
- Say 4m x Oceanflex 1.5mm tinned twin core cable (3m solar panel cables to charge controller, 1m charge controller to battery) £7.00 - less required for semi flex panel as that comes with 4m cable pre installed.
- 1 x Morningstar SHS 6 charge controller £22.95
- 1 x pair ring terminals (for connection to existing battery terminal (connectors) £FOC
- 1 x in line continental fuse holder and fuse £2.95
So a 2 x 10W Ameresco kit would come to £168.80 including VAT. You would need to wire the solar panel cables together and wire into the charge controller and battery terminals.
The other benefit of the 10W Ameresco panels are that they come with a channel each side on the back of the panel that allow a stainless steel M8 bolt head to be slid down the channel to allow easy mounting (give you more options than a whole at each corner).
Links to the products I mention above:
- Optimate 20 Solar Charger
- Optimate Extension Cable
- Ameresco 10W Solar Panel
- or PV Logic Flexi 10W
- Oceanflex cable
- Morningstar SHS 6 Charge Controller
- In line continental fuse holder
I hope that this helps. There are numerous ways of achieving what you are after so if you have other ideas that you would like me to look at please let me know.
All the products mentioned above are in stock and ready for fast dispatch with the exception of the PV Logic flexi panels which we should have in stock in the next few days.